If you wanted to have a computer-controlled dummy load you could simplify the circuit like this (untested):Now you just use analogWrite to set up the required voltage (and thus, load current). Since analogWrite (255) outputs 5V roughly then you would need to scale it. For example, to have a 2.5 A load you would analogWrite (127).
Not going to work with that wire going from pin 1 to pin 2 of that op-amp. Pin 2 should wire to top of the 1R resistor.
I think the main disadvantage of this circuit is the inefficiency due to the 1 ohm feedback resistor which leads to lots of wasted power. I would redesign it using a .1 ohm resistor and scale the feedback op-amp to compensate.
I used 20 1,000 1% resistors ordered on E-bay for just a couple of bucks.
Quote from: retrolefty on Feb 05, 2012, 03:30 pm I used 20 1,000 1% resistors ordered on E-bay for just a couple of bucks. I initially read that "I used 20,000 resistors". Wow, I thought, you have a lot more patience than me!Interesting article, thanks.BTW, when measuring the AC component of the dummy load it seems quite high (a few hundred millivolts) when the MOSFET kicks in, at least at the "edge" point. Would you recommend a capacitor somewhere to smooth that out? If so, what one and where?
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