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Constant Current Dummy Load Kits

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chrisw957:
I created a version of Dave's constant current dummy load for myself, and I'm still trying to get rid of the few extra PCBs that I put into a kit with the required parts.



You can get one here: http://www.sleepyrobot.com/?p=95

thanks,
chris

Kiriakos-GR:
What is the Min & Max current that your version can handle ?
And for how long time ?

sacherjj:

--- Quote from: Kiriakos-GR on June 03, 2011, 07:32:48 pm ---What is the Min & Max current that your version can handle ?
And for how long time ?

--- End quote ---

Parts list has 10x 1/4W 10 ohm resistors so it is 2.5W max for the shunt.  MTP3055 which I believe is a 12 A MOSFET.  With upgraded shunt (as long as the board can handle it) you could push more power.

With a 9V battery it looks like the op amp is getting fed from a 24k and 10k divider.  So that comes out to 2.64V (which will be 2.64A) with a little drop depending on how close to the rail the op amp can get.  So it is capable of about what the resistors are rated. 

I think that is right, just guesses by looking at the schematic.

Kiriakos-GR:
Hmmm ..

Well I need at minimum a 7A load that will work for an hour with out flames.
And the ideal is the 10A that it can keep up for an hour to five hours.
I have ultra large heat-sinks  and fans , but I need the PCB and some details about the wiring. 

JimmyM:

--- Quote from: Kiriakos-GR on June 03, 2011, 07:32:48 pm ---What is the Min & Max current that your version can handle ?
And for how long time ?

--- End quote ---
I just bought one. I was at the bench last night putting together an order at Digikey to build my own. I waqs experimenting with an op-amp I had on hand on a breadboard but couldn't get it to go don to 0V output. THEN I figured out why. It was the UA741 which can't get down to 0V with a single supply. I changed to +/- 9V and it worked perfectly. Plus it has an offset null adjustment. But then I'd need a dual supply... blah, blah, blah. But your kit has just about everything I was going to do with mine.
I'll be building it in a project box and will hack in a multi-turn pot I bought on eBay. I also bought a couple of CX101BG (or is it GB)s. One for volts and one for amps. I may fiddle with the 24k/10k divider to get more current out of it. But will be switching to an aluminum 1 ohm power resistor (10W) so I could potentially do 3+ amps. I also have several IRL8113 FETs to compare the 3055 to. nice going with the board though.

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