Electronic constant current DC load

[MJLorton]

Hi Folks,

With great guidance from my "design consultant" based in Canada...and hoping I follow the steps and execute correctly....here is the start of the build of my enclosure for my DC load.

I'll post HD pictures once complete....I've just dashed out of the garage to do this.....

[MJLorton]

Continued....

[SeanB]

Very nice Martin, nice work. I see where you have been shopping for tools........

[MJLorton]

Ok...a little more progress...

I should have used rubber cement to attached the 1:1 CAD drawing to the enclosure....but could not find any in the three shops I went to. I used contact adhesive, not the best idea, but it worked ok...just needed a little solvent to remove.

The drilled holes for the potentiometers are slightly out...again...I should have used a punch or pilot hole...next time ;-)....but there's a little wiggle room to move one up and the other down to have them almost perfectly aligned.

[MJLorton]

Very nice Martin, nice work. I see where you have been shopping for tools........

Thanks....not Game!

[SeanB]

No, Makro...... Looks like a little from Servistar as well, along with some from Midas.

Next time use Pritt, it works well, and just takes a hour or two to dry enough to hold firm enough to do the damage through it. Best if left overnight, but is easy to remove afterwards with hot water and a little soap.

love the nice drawings there, very nice. Nice case as well. With the pots I would suggest buying a taper reamer, i saw one and bought it from Builders, but you should be able to get them from many places. Try Buco, they are getting a reasonable range of tools, though it is rather store dependant.

[IanJ]

Hi all,

Taper Reamers are great as are the Step Drill Bit...........great for drilling panels, especially in the pedestal drill, and they will deburr as they drill.



Ian.

[SeanB]

Plus they are self centring as well. Those there are pretty well used I see.

Another thing useful is a hole saw set.

[MJLorton]

Gents....thanks for the valuable input....I had some of my holes go a little off center....I do have a larger step drill (too big) and will pop out now to get some smaller ones. (and hopefully post your package Sean!)

[SeanB]

Looks very nice so far Martin.

[MJLorton]

Looks very nice so far Martin.

Thanks Sean...hard and time consuming work for someone like me not used to doing this kind of thing... 

[SeanB]

Learning to do cabinetwork neatly is a long learning curve. I am still learning......

[MJLorton]

Advice taken from several folks....thanks!

I invested in some step drills....what a difference!

Another day at it and a little more progress....

[SeanB]

Where did you get the stepped drills and for how much.

Nice with the masking of the hole edges, but where is the heatsink compound under the Mosfet and sense resistor.

Like the captive nut for holding it down, next project purchase for you is a set of cheap metric taps and dies, so that you can learn how to thread the holes to make hidden fastenings and blind and low profile metalwork.

[IanJ]

Hi,

Per SeanB, you should isolate everything on the heatsink......it might work perfect on the bench but then one day you sit the heatsink on the case of a PSU you are testing and BANG!

A full mica insulating kit (with heatsink compound) under the mosfet would be good, but be careful to make sure it is tight and flat against the heatsink......I've seen the plastic top hats (they form part of the insulating kits) melt because the heat can transfer away.

Ian.