MJLorton Solar Power and Electronic Measurement Equipment Forum
Competitions and Giveaways => Competitions and Giveaways => Topic started by: MJLorton on December 21, 2012, 01:44:08 PM
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If you have not followed Steve Gibson (Shields UP!, SpinRite, etc) and Leo Laporte and their Security Now! podcasts you might be missing something...
This competition is based on the Security Now podcast where Steve talks about the Portable Dog Killer he made in his teens...it's hysterical:
http://www.youtube.com/watch?v=8Glft9CQ-5s
Steve is now developing a new version which can be based on several hardware prototyping platforms.
He has several forums where he is developing ideas: https://groups.google.com/forum/#!msg/portable-sound-blaster/VTNUYEPpy1U/7blr4TWRugEJ
Here is a link to some pics and info on the new prototype: https://docs.google.com/document/pub?id=1mfc5ZcuqU03ll2qyHl8URd1MvAYzr5swq2_SoCYmpIc
To pre-enter this competition you need to post a picture here of your multimeter placed somewhere interesting in your neighborhood, town or city.
Next...get cracking on researching and building the "Quiet Canine" device...and post a few updates along the way. At the end...even if it does not work for any reason...post a video and you will be in the final selection for the prize.
The prize will be a Uni-T UT61E and goods to the value of $150 from my Amazon Store: http://astore.amazon.com/m0711-20
For this competition to take place I need at least three entries by the 21st of January 2013...and at least two completed projects by the end of February 2013.
All the best and have fun.
Martin.
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I'm in. I had problems sleeping in summer, so I was considering a fixed version of the "hush puppy", but I can go portable as well. :) Interesting challenge.
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I'm in. I had problems sleeping in summer, so I was considering a fixed version of the "hush puppy", but I can go portable as well. :) Interesting challenge.
]
Brilliant...fixed or portable...it does not matter!
Please post the picture when you have time...
Cheers,
Martin.
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I will have to dig out the bodgy one I made years ago............ Wonder if it still works? The ones sold as pest repellents do not work on insects, though hopefully they do work on rodents, the cats certainly stay away from the garage door though. I do know that the gecko's are supremely indifferent to them, from the droppings that they leave in front of it.
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Yes, sorry about the missing picture, I was building up my strength to go outside :)
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Hi all, Just hopping in to post up my pic. I decided that since this is all about a PDK it would be best to first determine the resistance of a Whippet :)
Of course since he hates the cold he is so resistant my meter failed to get any accurate reading :P
(Don't mind my old cheapie mm.. my good fluke was sadly squashed years ago by a very heavy box.)
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Yes, sorry about the missing picture, I was building up my strength to go outside :)
Brilliant! Thanks for the post and entering!
(It looks a little cold from where I'm standing!)
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Hi all, Just hopping in to post up my pic. I decided that since this is all about a PDK it would be best to first determine the resistance of a Whippet :)
Of course since he hates the cold he is so resistant my meter failed to get any accurate reading :P
(Don't mind my old cheapie mm.. my good fluke was sadly squashed years ago by a very heavy box.)
LOL...great post and thanks for entering! :D
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This summer I bought one of those handheld cheap chineese dog chasers. It kind of works, so I decided to improve it, , upping it's power and making it into a fixed installation. Continuously outputting high frequencies is not a good idea, so I plan on building a band-pass "bark detector".
I mechanically broke it's piezo coupling transformer and threw it away, so I can't measure the original output voltage and waveform.
It's a classic 555 circuit, so I started there. In May I bought a 2$ tweeter so I used that. First I tried to lower the frequency for audio feedback, but I soon realized oscillator circuits behave differently at different frequencies, so I just stayed with 29 kHz.
While trying to connect an output transformer, I found that just paralleling an inductor to the piezo tweeter made it louder. Tried every inductor I had, and I found one that works pretty good.
I played around with different voltages, coils, capacitors etc.
losses suffered:
one 500mA HRC fuse (obvious cause),
one IRF540 (sustained overheat, now I added a heatsink),
one IRF1010E(sustained overvoltage) that also took out the 555 (lack of resistor+zenner on the output),
2-3 BJTs until I realized they pop at 65V, so back to MOSFETs.
a LED
one 63V (sure, Mr. Ling) electrolytic that scorched at 30V
one resistor that never saw it coming - red, red, black was not 22K :))
This is how it looks so far on the scope. Powered from 28V, and the 555 is 317'd down to 12V (for the FET). It draws some 30mA.
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Hey Martin,
First time and I'm not sure if I should address you or the chatroom gang but anyways;
I haven't gotten a photo of my multimeter in my neighbourhood vista yet but I didn't actually intend on getting so involved in this project to begin with.
I just started this whole electronics lark and was busy trying to understand capacitors and how they hold charge, when I came across the portable dog killer on my daily rounds of your videos. In general you have been an incredible help and I have follow your advice as often as I can.
As is usual when I tune in your enthusiasm (for the PDK) was infectious and I got to thnking over and over about things I havent a hope of understanding and then I remebered a kit I bought recently, based around the 555, it was an audio kit capable of generating a wave between 2kHz and 20kHz based on the altering of a potentiometer.
It took me six hours and I had to teach myself about soldering in practice but I completed the circuit design to spec.
My plan was to add a speaker and try to increase/modify the circuits already existing capabilities with larger resistors but there was a short, I overheated and half melted the IC's and now its toast but you were so encouraging about submissions from newcomers, that even though I cheated using the pre designed kit, did a half assed job and then roasted the poor kit beyond all recognition, I still want to submit my work.
I understand very liitle about the kit but in case theres any questions here's the spec and details; http://www.maplin.co.uk/media/pdfs/N41FL.pdf ,
Im sure all those on this site will know far more about it.
Anyway, this was my first attempt and will most likely be my last as I'd say Ive burned my poor fingers enough for one project, as well as neglecting my loved ones far too much and of course the added problem of not having the slightest notion of what I'm doing but I might give this another try, only time will tell , thanks.
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Skorch...hats off to you for jumping in and giving it a try.
Have a a break and come back to it once you have given time to your loved ones.
I really appreciate your post and hope to see more!
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Folks,
Just a note to say that you can use your own design...a kit...modify another design you come across (always credit / reference the original designer)....whatever...just give it a bash!
I also know that the Google groups what Steve Gibson used to open this project up for discussion can be rather confusing to follow. Steve has noted this himself. He will be moving all the relevant information to his own website (GRC.com) in the near future. I will post a link to it here when that happens.
Cheers,
Martin.
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Hi all,
in this topic (http://mjlorton.com/forum/index.php?topic=182.0) I'll describe design & construction progress of my version Portable Bark Killer. In my neighbourhood I have a noisy dog that long makes me wake up early. Therefore, this is the perfect project for me. I love dogs so I decided to make intelligent version of this unit to reduce emission of unnecessary ultrasound. Really portable unit needs good power management so design will be optimized for low power use in standby mode. I'm a fan of Texas Instruments MCU's so my first design assumption is to use msp430 device with cc430 to make wireless link. I would like to use remote control from my TI EZ430-Chronos watch and some digital signal processing for self-trigger mode.
Here is my ultrasonic consultant ;) :
(http://img708.imageshack.us/img708/1554/20130101012.th.jpg) (http://img708.imageshack.us/i/20130101012.jpg/)
(http://img651.imageshack.us/img651/2012/20130101014.th.jpg) (http://img651.imageshack.us/i/20130101014.jpg/)
(http://img5.imageshack.us/img5/9452/20130101006.th.jpg) (http://img5.imageshack.us/i/20130101006.jpg/)
(http://img835.imageshack.us/img835/5291/20130101.th.jpg) (http://img835.imageshack.us/i/20130101.jpg/)
(http://img831.imageshack.us/img831/8867/20130101018.th.jpg) (http://img831.imageshack.us/i/20130101018.jpg/)
Probably final functional diagram:
(http://img26.imageshack.us/img26/4486/diagrame.jpg)
More updates as soon as possible, in this separate forum topic. (http://mjlorton.com/forum/index.php?topic=182.0)
Cheers
blankfield
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Sign me up!
I have a few small outdoor automatic ultrasonic bark control units that have been dying. This is a good opportunity to come up with something better, and to add a manual wireless remote to trigger them.
Not much of an outdoor photo, it was about -10 C this morning.
(http://corgitronics.files.wordpress.com/2013/01/fluke_289-1_small.jpg?w=960)
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Hi all,
in this topic (http://mjlorton.com/forum/index.php?topic=182.0) I'll describe design & construction progress of my version Portable Bark Killer. In my neighbourhood I have a noisy dog that long makes me wake up early. Therefore, this is the perfect project for me. I love dogs so I decided to make intelligent version of this unit to reduce emission of unnecessary ultrasound. Really portable unit needs good power management so design will be optimized for low power use in standby mode. I'm a fan of Texas Instruments MCU's so my first design assumption is to use msp430 device with cc430 to make wireless link. I would like to use remote control from my TI EZ430-Chronos watch and some digital signal processing for self-trigger mode.
More updates as soon as possible, in this separate forum topic. (http://mjlorton.com/forum/index.php?topic=182.0)
Cheers
blankfield
Brilliant post and pictures! Thanks very much for entering; I look forward to your progress.
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Sign me up!
I have a few small outdoor automatic ultrasonic bark control units that have been dying. This is a good opportunity to come up with something better, and to add a manual wireless remote to trigger them.
Not much of an outdoor photo, it was about -10 C this morning.
Brilliant...love the picture!
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Steve Gibson is now officially calling this the "The treble shooter" which he has registered / trade marked.
To hear a little more about the progress he talks about it in Security Now! #385..goto 20:50
http://twit.tv/show/security-now/385
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Hey Martin,
I finally got the chance to get out with my old meter and take another photo of it in front of a famous Sydney landmark. While the landmark is the same as per my previous competition entry, in this image the vantage point is from the western side, and also includes the Sydney Opera House in the background.
As for the quiet puppy circuit, I am unsure what I will come up with, as I am much better at building circuits than designing them! Hopefully I'll get something happening! The practical side of me thinks maybe ear plugs or a big juicy bone from the butcher are possible solutions, however I am not sure where the battery would fit in either of those ideas...
Who knew that the soil near the harbour had a resistance of 35.1K!
Now all I need is a dog....
Love your work,
Michael
Sydney, Australia
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Nice, salty soil there.... I wonder it the PDK works on Vervet monkeys, I am having a problem with them recently.
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Hi,
I'm beginner in electronics... but I would like to learn!
I came across this while watching MJLorton ohm laws etc... :)
I'm waiting for 1ohm/50W resistors to create dummy load. This I wanted to be my first "big"(for me big, otherwise small) project, but it seems it will have to wait just little more :(
I have bought basics tools for electronics, kits of resistors, caps, diods... two multimeters and most expensive was Agilent oscilloscope - overkill for now, but I like to see signal on screen :)
I hope I will be successful in creating this ultrasound device, but I don't care, if I will not work, at least I will try :)
Maybe I will need some encouragement from you, but we will see.
First two pictures of multimeter:
Airport in Belgium - Charleroi on way home to visit perents and friends.
Third picture of multimeter: Airport in Slovenia - Brnik
Last picture: few things for this new device...
Regards,
Tomaz.
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Hey Martin,
I finally got the chance to get out with my old meter and take another photo of it in front of a famous Sydney landmark. While the landmark is the same as per my previous competition entry, in this image the vantage point is from the western side, and also includes the Sydney Opera House in the background.
As for the quiet puppy circuit, I am unsure what I will come up with, as I am much better at building circuits than designing them! Hopefully I'll get something happening! The practical side of me thinks maybe ear plugs or a big juicy bone from the butcher are possible solutions, however I am not sure where the battery would fit in either of those ideas...
Who knew that the soil near the harbour had a resistance of 35.1K!
Now all I need is a dog....
Love your work,
Michael
Sydney, Australia
Brilliant! Thanks as always for entering and your support Michael.
Cheers,
Martin.
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Hi,
I'm beginner in electronics... but I would like to learn!
I came across this while watching MJLorton ohm laws etc... :)
I'm waiting for 1ohm/50W resistors to create dummy load. This I wanted to be my first "big"(for me big, otherwise small) project, but it seems it will have to wait just little more :(
I have bought basics tools for electronics, kits of resistors, caps, diods... two multimeters and most expensive was Agilent oscilloscope - overkill for now, but I like to see signal on screen :)
I hope I will be successful in creating this ultrasound device, but I don't care, if I will not work, at least I will try :)
Maybe I will need some encouragement from you, but we will see.
First two pictures of multimeter:
Airport in Belgium - Charleroi on way home to visit perents and friends.
Third picture of multimeter: Airport in Slovenia - Brnik
Last picture: few things for this new device...
Regards,
Tomaz.
Hello Tomaz,
Welcome aboard and thanks very much for the introduction and entering this competition...great pictures too!
If you need help or support just shout as there are some very supportive...and wise folks on the forum.
Cheers,
Martin.
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Here I am too!
Tried to find a bizarre set for a photo, and I proposed my meter to measure the resistance of water, from inside... strangely it reFUSED.
After a while I convinced it to have some tests onto a kindle reader: it accepted.
Kindle kindly denied any permission:as you can see the meter feels high tension in the air.
Even circuits have a soul.
[The top behind is one on three of Monte Velino - 2487 m]
(http://mjlorton.com/forum/index.php?action=dlattach;topic=175.0;attach=1131)
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hey, so theres not to many vistas here in Cork City, some amazing architecture alright but well I'm fourth generation fisherman, "not by profession, by passion"(my grandfathers words in one of his soppyer moments), and so for that reason my photo was always going to be of the local river, the ever mighty River Lee.
This spot is just at the edge of the city and the weir is supposed to be a barrier to protect the river from this point upwards from the effects of the city as well as helping in the salmon runs of winter and spring, so from this point onwards up river, the river gets continually more beautiful and the fishing gets continually better, making it one of the bigger features of my childhood.
I know rakes more about it like local history and so on, but I wont bore you anymore than I already have with that.
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My grandmother came from that area. Born 190change, died 1922.
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Tis an awfully long way from here to there.
It's usually only the summer birds can manage a trip like that, your grandmother, god rest her, or her descendants must have accomplihed an awful lot in their time :).
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Died in childbirth ( so common at the time) and grandpa died at 89 from a broken heart when his second wife died.
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Here I am too!
Tried to find a bizarre set for a photo, and I proposed my meter to measure the resistance of water, from inside... strangely it reFUSED.
After a while I convinced it to have some tests onto a kindle reader: it accepted.
Kindle kindly denied any permission:as you can see the meter feels high tension in the air.
Even circuits have a soul.
[The top behind is one on three of Monte Velino - 2487 m]
Classic Post Riccardo! Thanks very much for entering.
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hey, so theres not to many vistas here in Cork City, some amazing architecture alright but well I'm fourth generation fisherman, "not by profession, by passion"(my grandfathers words in one of his soppyer moments), and so for that reason my photo was always going to be of the local river, the ever mighty River Lee.
This spot is just at the edge of the city and the weir is supposed to be a barrier to protect the river from this point upwards from the effects of the city as well as helping in the salmon runs of winter and spring, so from this point onwards up river, the river gets continually more beautiful and the fishing gets continually better, making it one of the bigger features of my childhood.
I know rakes more about it like local history and so on, but I wont bore you anymore than I already have with that.
Hello Skorch, thanks for the picture and post. I worked in Dublin for 5 months back in 2000 and did pass through Cork while on a little trip around the "Island".
Good luck and enjoy the competition.
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As Steve Gibson has found Google Groups too chaotic to track he is keeping the latest info up to date in this ZIP on his site:
For the Latest Design Documents, please grab the current copy of this archive: http://www.GRC.com/tqc/LatestDesigns.zip
Another link with general info and background: http://www.grc.com/tqc/TheQuietCanine.htm
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I'd like to sign up too! ;D
Photo story: multimeter out in the window, shot in the evening with 15 sec exposure time.
Thanks!
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Brilliant! Thanks for the picture and for signing up!
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So the back story to this is I came across this competition and with it, the notion of electronic ultrasonic sound effecting animals in a way unknownst to us. After my first attempt at it, I found myself left with a cool electronic paperweight and so was somewhat discourged.
However I heard recently that one of my relatives was having trouble with mice, the particular trouble was that they weren't actually in the house itself where you might stand a chance of catching them but instead between the floorboards and ceiling and potentially wall's.
So at a recent family gathering the all the men decided to discuss ideas as to how to exterminate these cunning creatures who had begun to take a liking to chewing out the wiring in my poor uncles house, taking lights, showers and T.V.'s out simply by stopping the flow of power to them from within the walls, this being made a worse problem as no electrician wanted the job of getting between those same walls to fix them.
The Conclusion of all the great men in my family combined as the women were discussing what to do if the mice got at the lovely curtains or gorgeous oak kitchen units, was that it was time to call in the professionals.
After being qouted some incredible prices my auntie and uncle were begining to think it would be cheaper the to let the mice have the godforsaken house(Nature 1 vs. Man 0).
Any way an exterminator was paid and the poor creatures were left to their faith.
(http://C:\Users\CIT\Pictures\Portable Mouse Scarer Awayer Mijiggy.jpg)
However upon a recent resurgence of the mice in several rooms of the house all hope was again lost, I quietly asked if I could test my device in one of their rooms and so far having now tried three different rooms over the course of a month, they feel its had such success that they want them fitted one or two to a room to every room in the house and now even the neighbours are trying to get in on the act.
My device is simple an arduino connected to a ping, running on one of the simplest of sketches that I could find on the internet, with very slight modifications just to increase range and delay times. As far as I know it generates a frequency of around 40kHz, which as far as I know is a frequency, such as one might expect from a young mouse when in distress, which was actually a total and utter fluke; of all the frequncies that it could have emitted it was that one.
But just before I go any further I would just like some opinions does this all sound reasonable to you out there in the know because I just cant believe what I'm hearing about these so called miracle devices and in all honesty I don't want to waste any of my relatives hard owned money as so far Arduino's have only been borrowed or have been my own and well my uncle would also have to consider the cost of labour, i.e. you wouldnt believe how many cups of tea/coffee and family meals I would expect to be invited over for after a favour such as this :D.
Anyway Thanks Guys!
P.s. Martin hard luck about your time in Dublin, tis as the folk songs sing a "dirty aul town" and this country has so much more too it, not that I'm saying Cork is infinately more beautiful and friendly than that so called "metropolitan city" but definately out west was worth a look, hope you managed to make it out that way as well because that city can often provide the wrong impression altogether of my country to the wandering man.
Im sure the irish tourism board would love this.
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Actually one more thing as well, one of the big disadvantages of this system as well is that its only works for a short period of time, before near as I can tell the serial monitor reaches its full capacity or it may well be the microcontroller or god knows what else?
Id like to find a program that doesnt require restarting every few hours via the usb trigger attached to my uncles laptop.
The program I currently using can be found at;
http://www.xappsoftware.com/wordpress/2012/03/15/how-to-interface-the-hc-sr04-ultrasonic-ranging-module-to-arduino/
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Hi Skorch
By a quick look to the code, the only bottle-neck I found is about the Serial.print; it's a heavy function indeed, capable to saturate the memory in few time under the worst conditions.
I suppose it writes the strings into RAM, and then it prints on the screen.
Maybe the string format is not optimized... I don't know.
I can only tell you to try recompiling the code without any serial communications; so comment the print function and see if it works.
I hope it will.
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Hi Skorch,
Thanks for the fascinating post....I love descriptive stories like that. :)
Scary how destructive mice can be!!! I've seen how bad ants can be with electrical and electronic appliances if they start nesting...I keep a sharp eye open of any ant trails these days!
I'll certainly give you a shout for some tourist info as I'm sure I will return to your neck of the woods for a visit in the future.
Cheers,
Martin.
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Hey Guys,
just a quick update, first off just wanted to thank RiccardoGiuliani, I am useless at code writing in arduino but I found a new more suitable program @ http://winkleink.blogspot.ie/2012/05/arduino-hc-sr04-ultrasonic-distance.html (http://winkleink.blogspot.ie/2012/05/arduino-hc-sr04-ultrasonic-distance.html) . With this we've had major success, after loading this program I took only one arduino around to each of the affected rooms in my uncle's house. Then assisted his neighbours in doing the same as one of the effects of scaring these mice away is that they have to go somewhere and they have. As a result of playing my program for fifteen minutes in each room, there has been four days of mice free living for both my uncle and as far as I know his neighbours aswell. We are all now hoping that this program might only need to be run once a week in order to be efffective which is going to save endless time and money as far as my uncle is concerned.
The best and by far the funniest news is that these mice appear to have "moved house", across the street into another set of houses and also my "services" are now being requested in several areas of my uncles large neighbourhood and several others are asking to be taught how to do this work with the arduino for themselves.
As a result of all this I am now quite quickly becoming endlessly popular, maybe not for the most desirable reasons but its always nice to feel wanted nonetheless :) .
Ants is another one I've encountered as well Martin and I have begun to wander with such large sensory antennae in comparison with their body what their "magic freqeuncy" might be and how difficult this absolute fluke of myne is going to be to repeat.
Really wanted to thank you Martin for this idea, its given me so much fun with new friends, old friends and family.
Its just a pity now that Im returning to college after holidays, it will be all biology again for a while but rest assured I'll do my best to keep up to date and I'll be back to try your next idea as soon as my course allows.
If I ever really can be of assistance with the tourism side of my country please do ask.
Thanks Guys
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Don't know if ants are affected by ultrasonics but I do know they follow live cables and tend to accumulate inside the boxes until they fill them and short the electrics out. Very common in pool pumps and gate motors. Gecko's tend to commit hara kiri on the boards as well, and destroy the board by the arcing they start.
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Thanks for the post Skorch!
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Well... it seems I'm posting a job for first.
Nothing transcendental, simply the basic NE555 astable configuration.
The big problem has been looking for an ultrasonic transducer, due to lack of time: luckily a local technician had and gave me a series of old remote controllers with ultrasonic transmitter.
I quickly tested the circuit, like in photos: the multimeter shows 30 KHz, maybe you're able to see the K at the extreme right of its screen. Frequency been measured directly on the transmitter (I suppose it's piezo).
Luckily again; it appears to be not polarized, so next step will be a test with a H-bridge of transistors, to double the output dynamics.
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Acquired some courage now that somebody made the first presentation :)
High res photos: 1 (http://i.imgur.com/ensFyyN.jpg) | 2 (http://i.imgur.com/r5i3RJA.jpg) | 3 (http://i.imgur.com/6OckdQm.jpg).
My Quiet Canine device on a breadboard as seen on the photos. Everything was pretty straightforward except maybe for the piezo tweeter; I eventually went for the KHS 107 because it was the smallest in size amongst the ones I found locally. The rest of the components came from China.
The circuit is working, but with the very first test I got a very very loud and deafening sound. I took it to a friend who has an oscilloscope and he told me that the output is somewhere around the 10 Khz area. So, it's audible by humans and I personally have the feeling that whenever I push the button a thousand braincells of mine die per second. It's really-really loud and bad for the ears. Trust me, I'm not exaggerating! Everybody be cautious! Wear ear protection! Or, the least you can do is put your tweeter facing down and wrap a piece of cloth or towel around it!
My case is a bit special and I almost suffered because of it. Luckily, together with Steve and his friends over at the Google Groups discussion thread we figured out that the KHS 107 is not the ideal tweeter. It has higher capacitance and this is the reason why I'm getting "only" 10 Khz sound. So, I have two options to reduce the capacitance: 1) reduce the value of C2 (originally 4700 pF, but in my case half of that would be ideal) or 2) use a smaller inductor (e.g. 680 uH instead of 1000 uH originally).
I'm about to decide what to do, but I'm having huge problems getting hold of components fast (i.e. locally). We'll see what happens. No enclosure yet so no idea how the final circuit will look like and whether I will solder everything on a PCB or not... :(
PS: On the last photo you will see a 560 pF capacitor. I found it on the PCB of an old satellite receiver so I desoldered it and tried it out. The output frequency got much higher, too high in fact, so I'll need a ~2000 pF capacitor, but at least this proves that playing with C2 does affect the output frequency.
PS2: once again, Everybody be cautious! Wear ear protection! Or, the least you can do is put your tweeter facing down and wrap a piece of cloth or towel around it!
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Hi all,
nice to have some pictures :)
On Saturday I also started building this ultrasonic device ;)
My first goal is to get sound around 22kHz. I don't remember where I was reading (in December) about this 22kHz, maybe I'm wrong, but I had to start somewhere:)... On wiki I saw it depends of the dog (breed and age), but they can hear up to 40kHz.
Since 555 can delever 200mA on output I was thinking why not driving it directly to piezo/tweeter?
It works, but, few problems and solutions:
- R1 was very hot after minute or so. I changed R1 with 1W resistor, but it will still go to 70C (pic3). Damm Ohm's law :):), thanks Martin for explaining it.
- I wanted duty cycles to be around 50%. I was thinking to make higher values of resistors so they wouldn't heat so much, but if I do, duty cycle increase also. I found possible solution here, to user diode:
555 and calculation:
http://www.horrorseek.com/home/halloween/wolfstone/TechBase/com555_555TimerCalc.html
My to-do:) but I hope 555 will still give me 200mA, I will see :)
- when I connect piezo tweeter to output, square wave is not so square anymore, but it works :)
- I tried battery and variable power supply. On variable power supply, if I change voltage on input also frequency change. I don't like this. Any ideas how to make frequency more voltage independent? I was thinking of 7805 or something like this? Reference voltage? But then I will also get lower output :(
questions:
- I was thinking to get sinusoid wave out of square wave. Would this produce better 22kHz sound?
Square To Sine-Link (http://www.wenzel.com/documents/waveform.html), or RC filter (3 pole): here (http://www.electronicspoint.com/convert-square-wave-sine-wave-t226443.html)
- the process above would decrease signal, would it be good idea to then use op-amp and increase volume of output?
- or if using square wave to use op-amp to increase volume of output even more?
Of course, you don't have to answer any of questions/problems, I'm just thinking while writing. Thanks for reading :)
Since I didn't use earplugs I'm heaving buzzz in my ears :( :( I hope it will stop soon:)
P.S.: Arduino/Rpi PWM would be too simple and we wouldn't learn anything about 555 timer :)
Tomaz.
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Decouple pin 5 with 10uF or so to ground, along with a 470-1000 uF capacitor directly across pins 1 and 8 will help with the stability. When I did mine years ago ( must dig it out and photograph it) I added a heatsink on the 555 to keep it cooler. Was helped by using the TO99 can version though.
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Any ideas how to make frequency more voltage independent? I was thinking of 7805 or something like this? Reference voltage? But then I will also get lower output :(
7805, 78L05 or a zener diode+R. This powers the 555, but you add a transistor on the output, thus all the logic is regulated 5V, but the piezzo gets the full voltage
- I was thinking to get sinusoid wave out of square wave. Would this produce better 22kHz sound?
Yes
Square To Sine-Link (http://www.wenzel.com/documents/waveform.html), or RC filter (3 pole): here (http://www.electronicspoint.com/convert-square-wave-sine-wave-t226443.html)
- the process above would decrease signal, would it be good idea to then use op-amp and increase volume of output?
- or if using square wave to use op-amp to increase volume of output even more?
If you use the output transistor, all your problems go away ;)
And since you're at it, find a switch mode transformer (usually yellow ones) and drive it with the transistor. The high voltage output goes to the piezzo. I've driven them up to 250Vpp and it's a LOT louder than at 4-5Vpp
-
Thank you for very good ideas (SeanB and dr_p)
I will try them. Yesterday I have disassemble old computer power supply and found yellow transformers.
There were 3 transformers, 2 of them yellow (bigger and smaller). I will try smaller :)
For transistor, I will try BUZ31, which I bought for DC load...
Tomorrow, I will report results.
Thanks again!
Tomaz.
-
Hi Tomaz,
I got nice results with self made step-up transformer HERE (http://mjlorton.com/forum/index.php?topic=182.msg1827#msg1827), one big advantage of this configuration is no need for series capacitance with piezo. Transformer cuts constant component of signal. You asked about square wave, for this application square wave is the best solution, sure it will add some harmonics on output (you will be able to hear some white noise but just a little bit) but on the other side you will get 100% of power at this supply voltage.
-
I'm really chuffed to see the progress and sharing ideas...please keep it up!
Cheers,
Martin.
-
Folks....let me know....would you like a bit more time or wrap up at the end of Feb? Remember, I'm not the judge so you'll need to post some kind of presentation or video of your device / work so others can see it.
Thanks again for participating in this one.
-
Hi!
I personally think that a bit more time would be great. I'm waiting for some more components and with those I can finalize the device, then I'll try to make the video, but I have no idea what to make it about. Anyway, I'm definitely finishing it during next week and hope to have some video by Thursday of Friday.
Will there be only one prize? How about first prize and second prize rather than giving it all for one? Just a thought. :)
-
Like for me one week is enough time to finish my project but if someone needs more time I do not mind the extension of the contest deadline.
-
Ok, let's extend to the17th of March so you have that weekend to complete and produce some little video / presentation on how you produced the device and if possible show its operation.
Judging will be opened to viewers and forum members from the 18th to the 21st...with the winner being announced on Friday the 22nd of March.
The prize for the winner is goods to the value of $150 from Amazon and a UNI-T UT61E...the runner-up will get a UNI-T UT61E.
Cheers, Martin.
-
Here's my first attempt:
Vision:
One or more remote controlled devices(annunciators) which will emit a high frequency audio pulse. One or more remote transmitters that can trigger all remote annunciators simultaneously.
Principle of operation:
- Transmitters will use the 315MHz ISM band. The transmitters will all use the same address/code. Matching ISM receivers, all set to the same address/code.
- The audio frequency is not critical, and will sweep across a range of 18 - 22 KHz.
- The audio will be generated by a PWM from a microcontroller.
- The audio burst should be 3-5 seconds in duration.
- The PWM signal from the microcontroller will be sent through a 2N2222A to a piezo speaker with a parallel inductor to boost the voltage.
- The device should be able to run on 5 VDC.
- The device does not need to be battery powered, so standby power consumption is not critical.
Components:
- RF remote transmitter: keyfob remote from Adafruit.com - based on the PT2262
- RF receiver: Simple RF T4 momentary from adafruit.com - based on the PT2272
- Picaxe-08M2 - why? had one laying around
- Speaker: piezo tweeter
- Power Supply - 5V USB plug-in
Circuit:
(http://corgitronics.files.wordpress.com/2013/02/bark_schm_f_small3.jpg?w=960)
Screenshot from my DS4024:
(http://corgitronics.files.wordpress.com/2013/02/bark_scope1_small1.jpg?w=960)
And, here's the code:
; Bark Controller
; initializes LED and Piezo to OFF
; waits for a signal
; when a signal is received:
; turn on LED
; step through a set of 3 tones, 10 times
; turn off the LED
; turn off the sound
; wait a couple of seconds
;
; Tones to play:
; frequency 18Khz = pwmout C.2, 55, 111
; frequency 20Khz = pwmout C.2, 49, 100
; frequency 22Khz = pwmout C.2, 44, 91
low C.4 ;LED is C.3 = PIN 2
pwmout C.2, off ;Piezo is C.2 = PIN 5
do ;input is C.3 = PIN 4
if pin3 = 1 then
high C.4 ;LED on
For b0 = 1 to 10
pwmout C.2, 55, 111 ; 18Khz
pause 100 ; play for 0.1 seconds
pwmout C.2, 49, 100 ; 20Khz
pause 100
pwmout C.2, 44, 91 ; 22Khz
pause 100
next
low C.4
pwmout C.2, off ; turn off the piezo
pause 2000
endif
loop
EDIT: corrected frequency in code comments.
-
Notifications failed to send emails to me, so now I'm reading some new interesting posts. :)
Glad to see the new end day.
I had got some time to quickly extend the ne555 astable configuration with an H-Bridge of general purpose bjts like in photo: the core of two couples of npn (top) and pnp (bottom), with two external, npn and pnp respectively to command the alternated opening and closing of the core.
My intent was to (quite) double the output dynamics, but without an oscilloscope I'm not sure about the result: what I can state is that the test I made today with a little dog met on street has totally failed.
The dog did everything but to run away.
Maybe the power supply change (from bench one to 9V battery) didn't give enough power; I don't know.
About the output frequency: I regulated the pot to get a 30KHz, as measured.
After that I measured on pin3 of ne555: got 60KHz.
So I replicated the basic astable circuit and I found the same values: 30KHz on transducer and 60KHz on pin3.
Bye
-
Hi all,
first thanks again for help and ideas :)
I have tried and failed, but here is my video of experiment of doing and testing portable device - with other words, I don't like the result, even if it is partially working :) Output volume is too low.
The idea was, to put everything in a nice small box, but till is not satisfactory working, it would be waste of time.
Here is youtube video made from few pictures (borring:):
http://www.youtube.com/watch?v=O3Wc_PFm0m0
and here is all the action - testing new portable device (http://www.youtube.com/watch?v=wHkwlRPfzRo): http://www.youtube.com/watch?v=wHkwlRPfzRo
H-Bridge idea was from one pdf, which I don't have on this laptop, but it is similar to this: here (http://electroschematics.com/1026/dog-repellent-circuit/) - btw output pin on right 555 is 3 and not 2.
On the end I noticed that one transistor and few small inductors do the same job with all three piezo tweeters I have.
Solved: variable input voltage -> on the output: different frequency - solved with 7805, thanks :)
New question:
- how to compensate temperature change of environment to have all the time same output frequency?
Thanks to blankfield, SeanB and dr_p I have learned just by experimenting that transformers have different input/output ratio not just by number of turns, materials,... but also from input frequency. I have tried few random transformers I salvaged from old devices and output voltage was differently on different input frequency...
Sorry I had to finish my development/improvement on 24.2. since I had to go away for 4 weeks - health treatment. But I'm really interested in what people will create here:)
Next thing to do: buy new better speaker:)
Regards,
Tomaz.
-
Hi Tomaz, really nice video especially this secret weapon in bag, and a pair of pliers as jumper :-) like my quick tricks. I'm suspecting that you are using wrong type of transformer core, probably Iron dust type, more useful for filters and less for power, but this is only my suspect. I did same mistake at beginning so it's worth to check this.
-
(http://imageshack.us/a/img802/1338/85810318.jpg)
(http://imageshack.us/a/img707/3199/89868306.jpg)
Hi all,
There is a time to write about final results of my project, this week will be very busy for me so I've decided
to write some description now. First of all I want to tell you about my challenges with this project,
now I know - output power is the most important factor to make a device meeting the job.
My unit produces almost 10W RMS output power (measured with audio output power meter with bandwidth
up to 22kHz) (0,95A @ 12V @ 20kHz) it's enough to intrigue dogs in range about 5m but not more.
Noisy dogs in my neighbour stops barking only for some while. My next step will be rewinding transformer
with thicker wires to use a maximum power of battery pack. Now I drain battery at 4A current level (@4,1V)
so it's low value like for 8 Li-ion cells, some space for improvements is available :). Another fail like for me
is bark detection now is working like analog comparator realised via ADC interrupt, my attempts to realise some
DSP takes to much energy and MCU power so I decided to drop my plans. I found really nice program to design
digital filters - WinFilter easy and works! In present configuration standby power don't exceeds 900uA which
is great result. My observations led me to set frequency below 20kHz I think that cheap piezo have huge drop
of power above 20kHz, my piezo speakers are affected by this effect.
but
Block diagram.
(http://imageshack.us/a/img405/6210/21452956.jpg)
Final schematics.
(http://imageshack.us/a/img12/6396/12830010.jpg)
Some internal mess:-)
(http://imageshack.us/a/img805/8185/80224701.jpg)
Assembled portable bark killer.
(http://imageshack.us/a/img43/9286/47220345.jpg)
(http://imageshack.us/a/img28/4227/49583933.jpg)
Output waveform loaded with 4 piezo speakers.
(http://imageshack.us/a/img62/3968/96247483.png)
Output waveform shape unloaded.
(http://imageshack.us/a/img209/8903/newfile4.png)
A new position in my watch menu.
(http://imageshack.us/a/img23/996/95890084.jpg)
At last I did some cell phone video, sorry about poor quality.
http://youtu.be/fhTo13PFoFI (http://youtu.be/fhTo13PFoFI)
Some source code.
Portable Bark Killer - firmware (http://mjlorton.com/forum/index.php?action=dlattach;topic=182.0;attach=1677)
Watch - firmware (http://mjlorton.com/forum/index.php?action=dlattach;topic=182.0;attach=1678)
All my other messages describing progress from sketches and experiments to the working device can be traced here:http://mjlorton.com/forum/index.php?topic=182.0 (http://mjlorton.com/forum/index.php?topic=182.0).
Regards,
blankfield.
-
Hi Tomaz, really nice video especially this secret weapon in bag, and a pair of pliers as jumper :-)
Yup...I second that...I was in hysterics watching it!
Great post Tomaz...even if the device did not work correctly...it was wonderful to see the "covert" effort in testing it.
-
Blankfield....thanks for your great post and video. Good luck good man.
Cheers,
Martin.
-
Howdy! :)
Here's my video too (HD Ready): http://www.youtube.com/watch?v=GjnFq6fCXwk (7:38)
As mentioned before, my device "shoots out" roughly a 20 kHz sound. Although none of the "test subjects" were afraid of it, I'm sure that they heard it; four of the dogs were strongly guarding their master's territory and the fifth one was so friendly that it came close in hope of some snack. Besides them there were several other dogs that I tested in secret (I wasn't brave enough to film it since their owners were too close).
For added fun, I included a spectrum analyzer too. :)
I definitely had fun during this project. I learned a lot about electronic components, practiced soldering, sound and video editing and most of all how to be creative. As a final conclusion I would say that my device needs more power, this 20 kHz sound needs to be louder. I am 100% positive that it wouldn't help much if there was no fence between me and the animal guarding the place. :)
Photo album: http://www.flickr.com/photos/birrbert/sets/72157632916200092/
Read about the concept here: http://www.grc.com/tqc/TheQuietCanine.htm
Latest designs (bill of materials and schematic): http://www.grc.com/tqc/LatestDesigns.zip
A big thanks to the following people:
- Steve Gibson, for the detailed schematic, bill of materials and continuous help
- Martin, for raising awareness about Steve's concept, involving and challenging us through a giveaway competition and moral support
- Tom Pascale, for playing the Entertainer on a piano and making it freely available on pianosociety.com
Software used to create the video:
- Corel Video Studio X6 Pro
- Virtual Dub
- WinAmp
- CamStudio
-
Great video birrbert! Mr. Curious reacts similarly like my dog, his eyes saying "why you doing me this".
I'm looking forward for other entries, maybe somebody will inspire me to improve my design. I would like to increase effective range before summer. Will be nice to have undisturbed sleep during summer:).
Cheers,
blankfield
-
Yes, that look is exactly as you described it. Straight look, raised ears, wondering 'What the heck is that?' :)
-
Hi.
First of all, thanks to Martin and to all others for the beautiful solutions i've seen before mine, which i show in this video:
http://youtu.be/dOC2bNJqdJs
Due to unsuccessful modifications i prefered to adopt the basic astable configuration, with an add: the outlook to a portable version suggested me to put an under-voltage device, the mc33163.
After all, it works. :)
-
At the start of this contest I thought "this is easy! Last time there were 30 people and there was no task. I have a real chance at this!".
Now I'm not so sure.... I've been trying for 2-3 weeks now to resume work on my Hush-Puppy project.
I started with a commercial product:
(https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTW_7XfraNngG9woHYx56stkfQaJZMO3qiNubuUq5nXN9-UMxjh)
I took it apart, analized the board, realized the f*ckers scraped off the IC's markings. WHY?!?! Why would you bother? I assumed it's a timer, obvious choice was 555, but it was DIL14, so 556 maybe? I traced out the pins and I'm 95% sure it's a 556. The second timer chip was used for the flashing LEDs.
So I built a 555 circuit on a breadboard. It worked at flashing a LED, then added a transistor, then faster pace, then added the speaker. It sort of works, as in you can hear the sound, but it way too low. It actually is 12V, just like the "battery" voltage.
OK, I thought, I can up the battery voltage, but up to what point? I's not a viable solution. I have to do something on the output. What I need is a transformer. I tried adding a mains transformer to up the voltage, but that seemed to make little difference.
This is when things started to change: I accidentally connected the transformer while the piezo was still connected. A massive increase in volume. WOOOO!! where did that come from?! Inductive kick-back, probably, as the high peaks were negative. CH2 is the 555 output, CH1 is the onverted piezzo voltage.
(https://lh4.googleusercontent.com/-4AXQomWX4Uk/UUZK_ioZhyI/AAAAAAAACsU/tccR_lemjHQ/s640/New1.jpg)
All is well untill things start to go south - first a transistor goes up in smoke, then another one, then a 555. At this point I am thinking the transistor has to withstand that high voltage, so I get a MOSFET, being that none of my BJTs go up to 60-70V. I manage to find a 60V FET, that one runs for like 1 minute ultill it goes pop, zener too, 555 too.
I then tried different inductors only to reach the logical conclusion that more inductance yields a louder sound (more kick-back). I settled on a mains filter. Further breadboarding testing got me frustrated because wires kept coming off, contacts were not perfect, so I built a PCB for it.
(https://lh4.googleusercontent.com/-i0rYnRK6QGg/UUZE49YbDAI/AAAAAAAACr0/LjxnrWV86qc/s753/IMG_2651+%28Custom%29.JPG)
Next run gets me an exploding elactrolytic (happened to be a low ESR one) and anothe 555. At this point I resorted in adding a socket for the IC and also adapted SMD 555s for DIL usage. I also placed an order for 20 555s, 50 high voltage transistors and lots of caps. Pictured here are only some victims of this carnage:
(https://lh4.googleusercontent.com/-B8chXv-72pU/UUZN9YjxeZI/AAAAAAAACsc/ftOnkoTexI4/s753/IMG_2660.jpg)
Now I realize this only happens when I run the circuit without the piezo speaker. Meaning all of the inductive kick-back goes back on the power rail, instead of in the speaker. I become extra carefull in not running the circuit without the piezzo. I also start wearing gogles, since the last capacitor blew right in my face (I mounted it in reverse polarity).
OK, so now I get to thinking why is the voltage settling on 60V? How much voltage does the commercial unit give?
At this point I have to say my yellow commercial unit unit was made deffective by my poor skill at unsoldering the transformer. I broke it, got mad and threw it away. My better half took out the garbage, so by the time I realized I overreacted, it was too late, the transformer was gone. By this time I borrowed a unit from a friend.
Measured the output, it was 240vpp, perfect sinewave. The board looks like this:
(https://lh3.googleusercontent.com/-etHsG8TcPQM/UUZE50Pv5qI/AAAAAAAACsA/6Cht8po5pog/s565/IMG_2655+%28Custom%29.JPG)
(https://lh3.googleusercontent.com/-RtQ5tfCrHYc/UUZE6AbCLqI/AAAAAAAACsI/ytKc8NousrU/s565/IMG_2656+%28Custom%29.JPG)
and as you can see there is a my-name-is-Martin-and-I-think-it's-for-calibration potentiometer. And by that very logic I assumed it was for frequency adjustment. I fiddled around with the settings until I realized it was for someting else, perhaps the duty cycle. Working the potentiometer did not really modify the frequency by much, but it made it look way off from a perfect sinewave (on the piezo side).
So I took that as a challange and thought "why 240Vpp?!? The chinese surely got it wrong, I can go higher." I back-traced the circuit and figured the 555 was powerd from a 6V zener (can't remember exactly). I replaced it with a 7V zener and all hell broke loose - the waveform was way off, maxed at some 50Vpp. Replaced the original zener, realized it's sole pupose was to stabilize the 555s frequency, since the piezo was run off the transistor. I never managed to achieve those 240Vpp again, only 220Vpp. I returned the unit to my friend, he stated it "works" just as fine (on shy dogs, if you ask me...)
All of this time I have been using this piezo:
(https://lh4.googleusercontent.com/-iv_FTHsmZD0/UUZE42U9tqI/AAAAAAAACr8/dAuJ8E_PmLo/s753/IMG_2653+%28Custom%29.JPG)
but after a brief shopping spree I got a hold of these
(https://lh4.googleusercontent.com/-z4Flp4fl0iA/UUZE5nGIS6I/AAAAAAAACsg/Axwlb7h8z3I/s753/IMG_2654+%28Custom%29.JPG)
After a few weeks of break, I returned to my project. I started with another aproach - an LCD inverter. I tweaked the components to give me the right frequency (15-30kHz) and all went well, untill I connected the piezo. The output went way low, just like the transformer was shorted. It now comes to mind that maybe a series resistor would have changed thing...
(https://lh4.googleusercontent.com/-iBR7DvJvWH4/UUZE4yUxReI/AAAAAAAACrw/V2xUrJm2GuA/s753/IMG_2652+%28Custom%29.JPG)
I then reverted back to the 555 circuit and tried a higher supply voltage - 30V from a printer SMPS. The voltage would not go higher that 60V, no matter what.
Unfortunatly, somewhere in here my car broke down. I took it to a specialist that told me X is broken, he can fix it for ~800$. That made me angry, since I knew X was ok. Decided to be my own mechanic, so I started learning shi... stuff. I am still learning and fixing and this is taking most of my spare time. It's not that difficlt, but since I never did it before...
That is why I cannot properly complete my project. I never got to the point where I try Steve Gibson's single FET circuit. I would have liked to do that.
Wohooo, this took some time to post.
-
Thanks very much for your post and efforts dr_p!
Please keep us up to date with your progress even though the competition has ended.
You are still a valid entry.
Cheers,
Martin.
-
Riccardo, your device is very strong. I can tell that just by hearing it through the video. All the dogs avoided you, except the first which is understandable because it was quite far. Didn't you get a head ache or ear pain? :)
But seriously, how did you make it this loud? I'm asking because I can't decide why mine is so weak... because of the capacitors or the tweeter...
-
birrbert
ahahahahah, maybe the only remarkable feature on my device.
And a true luck!
The very first transducer didn't work, i think due to my bad knowledge of it: i found nothing clear on the net, and got nothing by trials and errors... i'll retry in future.
For an amount of coincidences i got the working speaker only at the last minute, with no time to expand the circuit in power... but we're agree it doesn't need it more. ;D (i made everything on sunday)
The already attached cap is a 3.3uF 50V; don't know anything about the speaker, sorry; just a series number in blue: 30194.
This apart... i was surprised to hear so clearly, especially the first time when i put the ear close to the speaker; very stupid!
So as suggested in a previous post the ears' protections are (were) welcome.
A nice day to everybody!
-
Gents, please note and this is important.
Votes should come from viewers who have viewed the entries and made their own decision on who to vote for.
Please do not encourage friends / strangers to post your name.
-
Hi Martin, it will be really hard to count valid votes, for now almost all votes become from same countries like participant. Maybe a kind of eurovision vote system should be applied;).
I think best would be jury of forum members even registered before competition. As for me, the most valuable is the opinion of hobbyists, enthusiasts and those involved in electronics, and these opinions are only a few unfortunately. It would be great to read a constructive comments what is done well and what could be improved :). For now contest become "vote for beer" for friends, family etc.
Regards,
blankfield.
-
I suppose everyone is talking about my votes. I now see how this can look unfair or even suspicious.
People that voted are indeed acquaintances of mine, true. It's obvious since the giveaway didn't get any publicity outside the forum/youtube , and they're all from Romania.
Truth be told, I made it known I'm participating in a contest. Almost all said "Finish the project, make it work, because I DEFINETLY WANT ONE TOO" (the device). Some inquired about voting, and I guess adding the country "camaraderie" and the fact that you know the person, decided to vote. The reason was not skill or successfullness, it was potential usefulness and subjectivity. At the time it didn't raise any questions, cause I felt it was in the spirit of the giveaway while also not braking any rules. I still feel that way, but I do realize it has gone into strange territory.
I'm not trying to jerk anyone here, but if it's deemed to be inappropriate, feel free to take whatever measures are necessary.
May I also suggest that future contests be organised differently?
The latest eevblog rules are interesting. With modifications:
- Martin makes the rules, Martin breaks the rules, deal with it.
- only existing members at the contest start date
- if it's a straight giveaway - at least 5 useful posts or 1 very good one (will be checked for)
- if it's a contest (you have to earn it) - random extraction or forum based poll with above user limitations
-
To be honest for me it's really hard to pick an overall winner - there's bit I like from all of these ;-) couldn't you put the names into a hat and pull the winner? Maybe for next time you could design and build a novelty electronic name chooser machine? ;-)
-
I like the work blankfield has done. I agree it's a complicated approach, but certainly interesting.
-
Thanks for the input Blankfield and dr_p.
My fault really...let the voting continue and we'll make a call at the end.
I'll learn from this one and have better voting guidelines for the next one.
Cheers,
Martin.
-
In that case, I went through all the posts again this morning and I finally decided to vote for blankfield
(Edit)
The reasons why my vote is with blankfield is simply because I feel he has done a really good job at documenting his great project.
-
Hi All,
At first thanks for voting my project.
Finally my portable bark killer works since today! And I'm very happy about this.
I spent today's evening to disassemble step up transformer that I've made some time ago.
It was a very productive time, I found some mistakes in alignment of 2 part ferrite core
that caused a high power loss. Next I have tried a brand transformer exactly
Colilcraft FA2443-AL (6:1 ratio) and results just shocked me! Huge different in power.
This inspired me to make another attempt to rewind my new transformer, I used
thicker 0.5mm enamelled wire 5 turns in primary side and 70 turns on secondary side.
PBK became so loud so I had to increase frequency from 16kHz to 20kHz. Output power
become even more stable than before. I thought for some while that I damaged
the MSP430 MCU but only 5A fuse just blown. For now power consumption in mode of 100%
output power rises above 33W (7,9A @ 4,2V) (power from battery pack).
Mosfet become quite hot (about 60 'C after 30s) but there is no need for heat sink.
My future steps will be:
* find 'of the shelf' transformer that will be have decent windings and 20:1 ratio and capable to transfer 50W
* design proper PCB
* develop code that can be easily modifiable
* release all files as OS
Neighbour’s dogs are not so happy like I :)
Take care,
blankfield.
Some additional photos:
Colilcraft FA2443-AL:
(http://img850.imageshack.us/img850/1070/20130327147.jpg)
'Naked' core:
(http://img811.imageshack.us/img811/5088/20130327151.jpg)
(http://img802.imageshack.us/img802/6589/20130327150.jpg)
And some ugly windings (it's hard to rewind transformer without core casing):
(http://img542.imageshack.us/img542/552/20130327153.jpg)
(http://img145.imageshack.us/img145/8374/20130327156.jpg)
Test jig:
(http://img818.imageshack.us/img818/4883/20130327158.jpg)
(http://img94.imageshack.us/img94/9982/20130327160.jpg)
(http://img405.imageshack.us/img405/9586/20130327157.jpg)
And a evening mystery - blown 5A fuse:
(http://img5.imageshack.us/img5/8176/20130327159.jpg)
-
do you have a scope? or maybe at least a DMM set to %? I think most of the power is lost because you're not feeding a symmetrical signal to the transformer. When I played around with the trimpots, having the output "idle" high made the transformer heat up considerably. 30W of audio is a lot IMHO. Does the transistor heat up?
-
Well... I must admit my fault in giving details.
Stimulated by others contenders with their beautiful projects and reports I'm here posting the KiCAD scheme of my device, with the advice that you must substitute:
1) the LM555 with a NE555 (not important: but any case KiCAD has not NE555 model);
2) the 78L05 with the MC33164P (this last one not present in KiCAD).
Thank you (I saw three votes for me until now: I couldn't image this result for an inflated classical device made for playing).
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do you have a scope? or maybe at least a DMM set to %? I think most of the power is lost because you're not feeding a symmetrical signal to the transformer. When I played around with the trimpots, having the output "idle" high made the transformer heat up considerably. 30W of audio is a lot IMHO. Does the transistor heat up?
Hi dr_p,
Writing 100% was my mental shortcut, of course I'm feeding square wave 0 - 4.2V (4.2Vpp) with max 50% duty cycle @ 20kHz. Power losses are dissipated on series resistance of Mosfet Rds_on + resistance of wires + internal resistance of Li-ion cells. Some energy returns to GND via mosfet's diode while mosfet is shutting off. Rest of power saturates ferrite core and transfers to secondary side. Voltage and current on secondary side is depended to transformer ratio, with a large simplification of course.
What you mean writing 'symmetrical' are you using symmetrical supply like +/-12V or you mean duty cycle?
blankfield
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I meant 50% duty-cycle but you already covered that. Maybe I'm wrong, but still 30W seems like a lot. I'm insisting because my experiment also used to eat a lot of power. I had a common mode choke with both coils wired in series, but generating opposing magnetic field. For no reason, it was just silly, and accidentally reversed one's polarity, so now they're not opposing any more. Current draw went down from 450mA to 20mA and it was almost as loud (at 3kHz). I'm not ace at inductors, but shouldn't the core NOT be saturated?
Anyway, how do the test subjects react to this? :D
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I'm using ferrite bead core capable up to 50W power applications so I'm in half a way to saturation. 30W is reasonable like for 4 piezo speakers, one can be driven at 10W. Power losses and heat in your project appeared because you're using wrong type of magnetic material. This small common mode choke have ferromagnetic iron core (iron dust), good for filter applications on 50/60Hz common lines. Useless for high power and frequencies like 20kHz. For this frequencies your choke 'have only primary side' because 'power' (magnetic flux) at this frequency cannot pass this cheap material core. Tray to run typical 50Hz transformer at 20kHz and you will get same effect. So you getting only heat on mosfet and primary side windings. Try ferrite core and fell (hear) difference ;-). I'll made some update on weekend.
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Congratulations to blankfield and dr_p!
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Thanks Riccardo :),
I'm still working on my PBK, I've some new clues according how to reduce audible frequencies on output.
For today I used 20kHz frequency but I still hear some noise, digital FFT in my scope showed why. On first picture we can see FFT for 20kHz output waveform captured at speaker connectors. Some part of spectrum covers audible range even down to 14kHz. Now I'm using 28kHz frequency and a lower margin of spectrum is above audible range.
I've also checked power balance,
ON state:
Power from battery cells RMS : 33.5W (8.0732A @ 4.15)
Power output RMS : 30.05W (1.7354 A @17.32 V)
Power dissipated mosfet + windings : 3.45W
Standby:
Power from battery cells RMS : 3.94mW (950uA @ 4.15)
(http://img194.imageshack.us/img194/6871/newfile0b.png)
(http://img542.imageshack.us/img542/8677/newfile2.png)
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Hello.
Is there some progress anywhere?
Is this competition still running?
Or is it closed?
And the winner is...?
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Hello.
Is there some progress anywhere?
Is this competition still running?
Or is it closed?
And the winner is...?
Hi ProBang...it is "officially" over and a winner was announced...but if anyone wants to build one and demonstrate it working I will certainly cover it in a T4D video.
Cheers,
Martin.