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Basic electronic load


Guest liquibyte

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Guest liquibyte

I'm tired of not having a proper load to test my supplies out with so I started searching for designs.  I ran across many but most of them were mental masturbation in my opinion.  I wanted something simple and found this (about halfway down the page).  I started simulating and got pretty good results but since I didn't want to power from the load under test and I didn't need 10A I made a few changes and got it to use standard parts I had on hand.  The only oddity is the 500 ohm 10-turn pot that I'm using.  You could tweak the values for R3, R4 and P1 to use a 1K, 5K or 10K pot if you wanted to.  The sense resistor is actually part of the display I ordered for this specifically but I didn't know it at the time and had planned on using two 0.1 ohm 3W resistors in parallel.

I'm in the process of building this up now but have to wait for a few weeks for stuff to arrive from China.  I'm putting this in an aluminum case but plan on doing some heat exchange with a 12V peltier that I salvaged.  I've got most of the case built up already using the stuff I did have on hand and I'll post pics of what I've done so far if someone wants to see it.  Once everything arrives (display, TO-220 insulators, fans) I'll post pics of the project as a build tutorial and explanation of the design choices I made as I went.  By my estimation this should be able to handle about 150W or so in its current form.  The only thing that has me worried is condensation from the peltier but I think I've found a solution to isolate the innards from the effects of that.

I've attached the spice file and models (TL071, LM317) if anyone wants to play around with changing the values to use what you have on hand.  I have a ton of LM317's on hand so that's why I used a separate model instead of the standard 12V regulator that comes with LTSpice.

post-107142-14279144896247_thumb.png

load.zip

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