Author Topic: 40V/5A Watt Meter Kit  (Read 14729 times)

iloveelectronics

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40V/5A Watt Meter Kit
« on: April 29, 2013, 11:48:32 AM »
A while ago Martin reviewed an uncased watt meter I sent him:

http://www.youtube.com/watch?v=cCd2DDoz38g at 25:35
http://www.youtube.com/watch?v=VBxwdkOyf2I at 26:06

I had a number of those but they sold out very quickly and unfortunately the manufacturer decided to discontinue to product so I couldn't get more of those anymore. I have since tried to look for an alternative and tested a few until I found this kit which is based on essentially the same circuit using the same ATTiny26L microcontroller, running the same firmware from the original designer. The main difference is that this kit is smaller in size, and that it comes with an older version of the firmware. I have finally learned how to flash new firmware on to the chip so I am now ready to start selling these, with the latest firmware (same one Martin reviewed).

The following are a few pictures of the kit, before and after assembling. The LCD panel that comes with the kit has no backlight. I'm pricing the kit at $14, worldwide air mail shipping included (no tracking). If you want tracking I can send it using registered air mail for an additional $2.4. I can also offer a backlit LCD for an additional $2.5 (you will get 2 LCD's in that case, one with the backlight and one without).

Either leave a message here or contact me via PM if you're interested. Thanks for looking!

Cheers,
Franky

« Last Edit: October 31, 2014, 12:05:42 AM by iloveelectronics »
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

SeanB

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Re: 40V/5A Watt Meter Kit
« Reply #1 on: April 29, 2013, 12:21:48 PM »
Nice, Can I get a copy of the firmware?

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #2 on: April 30, 2013, 12:42:51 AM »
You can download it from the original designer's website: http://blog.21ic.com/user1/4577/archives/2007/43308.html

You will see a link that says "UploadFiles/2008-3/12052445228.rar" about 1/3 down that page and that's the last version of the firmware he released. It's only a HEX file though and no source code. I think I did contact him once about the source code but didn't get any response. Perhaps I'll try again some time.

The files have Chinese file names though so you might want to rename them after downloading.

Nice, Can I get a copy of the firmware?
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

birrbert

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Re: 40V/5A Watt Meter Kit
« Reply #3 on: April 30, 2013, 07:17:48 AM »
HI Franky!

Could you please post the size of the assembled meter? I'd like to know roughly how much space (length, height, depth) it needs.

Also, do you have any info about the resolution and the accuracy? Maybe a photo while the meter is turned on and taking a measurement?
"Dubito ergo cogito, cogito ergo sum." Descartes

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #4 on: April 30, 2013, 11:22:45 AM »
The assembled meter measures (roughly) 84mm (L) x 38mm (W) x 28mm (H). There is, however, a metal tab that holds the LCD to the PCB that doesn't sit too well with the connection terminals, which actually didn't come with the original kit but I thought they would make connections easier. See the attached picture. That makes the meter a bit thicker on one side than the other. That should be fixable by either removing the tab or not using the connection terminals.

I have also included a few pictures of the meter taking some measurements. I powered the meter with 3 AA size batteries (so not exactly 5V). The input is connected to a power supply. Output is connected to an electronic DC load (the Maynuo M9712 Martin reviewed). Multimeter (Brymen BM-521) is connected to the output (load) end.

I tested the meter at about 2V/100mA, 5V/500mA and 20V/3A (my power supply can only do up to 20V). There is some voltage drop in the leads between the power supply and the meter, as well as between the meter and the DC load. But as you can see in the pictures, the voltage readings of the meter and the Brymen are pretty close. The current readings on the meter and the DC load aren't very far off either across the range.

Hope this helps.


HI Franky!

Could you please post the size of the assembled meter? I'd like to know roughly how much space (length, height, depth) it needs.

Also, do you have any info about the resolution and the accuracy? Maybe a photo while the meter is turned on and taking a measurement?
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

birrbert

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Re: 40V/5A Watt Meter Kit
« Reply #5 on: May 01, 2013, 12:17:45 PM »
Thank you very much for the details!

I like the three digit resolution both on the Volts and Amps. It's and excellent meter in my humble opinion. I should've bought this for my variable power supply, because the one I used measures down to only two decimal places on the Amps and to one decimal place on the Volts.

What kind of color does the back lit LCD have?
"Dubito ergo cogito, cogito ergo sum." Descartes

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #6 on: May 01, 2013, 10:53:11 PM »
Thank you very much for the details!

I like the three digit resolution both on the Volts and Amps. It's and excellent meter in my humble opinion. I should've bought this for my variable power supply, because the one I used measures down to only two decimal places on the Amps and to one decimal place on the Volts.

What kind of color does the back lit LCD have?

The ones I have in stock are white text on a blue background. I can get the ones with green background easily as well at the same price. If you want other less common colours I will have to look and pricing will be higher.
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

vrun

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Re: 40V/5A Watt Meter Kit
« Reply #7 on: October 18, 2013, 12:14:02 PM »
The ones I have in stock are white text on a blue background. I can get the ones with green background easily as well at the same price. If you want other less common colours I will have to look and pricing will be higher.

Franky

(new here )
Blue would do fine ... if you still have any available.
Can we order ?  (if it works pls pm me)

Your link to haikang does not lead me to the source code...

BTW: I am a long time member of ebay.com too but nowadays all of europe cannot access any of your ebay shop...
 _but_ with a direct "eBay item number:" you can circumvent all restrictions
Maybe you want to post a list  ;) in a new thread   8)   (I know you did that for the UT61E already)

Regards
Reinhold

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #8 on: October 18, 2013, 09:47:17 PM »
Franky

(new here )
Blue would do fine ... if you still have any available.
Can we order ?  (if it works pls pm me)

Your link to haikang does not lead me to the source code...

BTW: I am a long time member of ebay.com too but nowadays all of europe cannot access any of your ebay shop...
 _but_ with a direct "eBay item number:" you can circumvent all restrictions
Maybe you want to post a list  ;) in a new thread   8)   (I know you did that for the UT61E already)

Regards
Reinhold

Yes for some reason the original blog site has been updated and a lot of information was lost during the process. Try the archive.org link here: http://web.archive.org/web/20120202214912/http://blog.21ic.com/user1/4577/archives/2007/43308.html

I still have these in stock and will send you a PM regarding purchase.

As for my eBay store not being accessible in Europe, I believe it's not ALL of Europe, but mainly just Germany, Switzerland and Austria, as I am still getting orders from other parts of Europe. Your item number trick does work, so does using the mobile eBay app on smartphones and select a different country there.

One of these days when I have time to actually do it I will create my own website so I don't have to rely solely on eBay :)
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

vrun

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Re: 40V/5A Watt Meter Kit
« Reply #9 on: October 19, 2013, 05:17:11 AM »
...as for my eBay store not being accessible in Europe, I believe it's not ALL of Europe, but mainly just Germany, Switzerland and Austria, as I am still getting orders from other parts of Europe. Your item number trick does work, so does using the mobile eBay app on smartphones and select a different country there.

Hi Franky
(Thanks for PM ... you'll find my reply)
You should/could also be in a position to receive orders from "ebay.de".  Same for the UK (at least in August when I tried last) ...
It's just that they neither can search for your items nor find them in your (empty) store.
Some chinese shops put an app in there store and all items are displayed in a horizontal scroller at the bottom,
... while on top it says "no items" ;-)

Would I find a TP or DT400ZC in your shop if I could look ?
Found it: ebay item 200912705694  ;)

Regards
Reinhold
« Last Edit: October 19, 2013, 05:20:02 AM by vrun »

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #10 on: October 22, 2013, 07:34:10 AM »
The following is the calibration procedure for this kit. It was actually posted a long time ago in another thread when Martin reviewed the original meter I sent him, which is physically different but uses the same chip and firmware. I thought I would re-post it here:

1. Connect an accurate multimeter at the output end of the meter to measure voltage. Connect the variable power supply to the input wires.
2. Hold the calibration button down while you power up the meter. Release the button after a couple of seconds.
3. The screen shows 0V, make sure your power supply's output is turned off and the multimeter reads 0V.
4. Push the button again. The display now shows 2V.
5. Adjust the input voltage until the multimeter reads 2V.
6. Push the button again. Now the display shows 19V.
7. Adjust the input voltage until the multimeter reads 19V.
8. Push the button again. Now the display shows 0A.
9. Disconnect and reconnect the leads on the multimeter to the Amp range and switch to Amp measurement.
10 Switch off the power supply's output so the multimeter reads 0A.
11. Push the button again. Now the display shows 1.9A.
12. Adjust your power supply's current output until the multimeter reads 1.9A.
13. Push the button again. Done!
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

thunderheart

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Re: 40V/5A Watt Meter Kit
« Reply #11 on: May 29, 2014, 10:09:08 PM »
Either leave a message here or contact me via PM if you're interested.

Hi Franky!
I've just registered here for this meter!
Please, tell me
1. Does it do reverse measurement?
2. What voltage it needs to be powered? (i can see it is auxiliary powered in photos)
3. Do you sell them calibrated or not?

Thank you (and Martin too)!

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #12 on: May 30, 2014, 12:46:09 PM »
Either leave a message here or contact me via PM if you're interested.

Hi Franky!
I've just registered here for this meter!
Please, tell me
1. Does it do reverse measurement?
2. What voltage it needs to be powered? (i can see it is auxiliary powered in photos)
3. Do you sell them calibrated or not?

Thank you (and Martin too)!

Thanks for the interest!

1. No, it doesn't do reverse measurement.
2. It's supposed to be 5V. I use 3 1.5V AAA cells to power it and it works fine as well.
3. It's a kit that you need to assemble so I can't possibly calibrate it beforehand. I have posted the procedure for calibration earlier in the thread though and it's not a difficult process. You just need a reasonably accurate multimeter and a DC power supply capable of up to 19V and 1.9A output.

Cheers,
Franky
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

PhildOwen

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Re: 40V/5A Watt Meter Kit
« Reply #13 on: September 08, 2014, 08:10:49 AM »
Franky,

I appreciate that I'm a little slow and late on this but do you have any of these kits left in stock?

Thanks

Phil

iloveelectronics

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Re: 40V/5A Watt Meter Kit
« Reply #14 on: September 16, 2014, 06:57:12 PM »
Franky,

I appreciate that I'm a little slow and late on this but do you have any of these kits left in stock?

Thanks

Phil

Hi Phil,

Sorry about the late reply, haven't visited the forum for a while. Yes, I still have some in stock. I'll PM you.

--Franky
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com