Hi all, I am back with another stupid question.
I have a resistor as a DUT. This resistor (unknown material) can handle a shit ton of wattage. Its resistance at room temperature is
10? and when put into a test oven at 185C is
20?. My task is to force in 2A of constant current into this DUT and monitor if it breaks down or not.
Since the resistance is variable, I can not only rely on a voltage source, hence I need a current source that I can hook up to my lab power supply (it can supply 50V@3A, 150watts).
I have already an
APEX MP38CL power amplifier that I hope to abuse its current limiting feature to achieve this task. In datasheet its written that the current limiting resistor can be calculated by
0.7/I where
I is the desired current. In my case, R will be 350m?.
I want to be able to turn on/off this current using digital output of a micro (3.3V). Something like this:
I know there will be at least 80watts dissipation in the op-amp?? I will be using an intel stock fan too cool it down!
Here is my actual questions:
1- How can I use that 3.3V signal to tell the OpAmp to enable its output without a feedback loop that has a gain of like 13 (15x3.3 roughly 40V). But I guess it has all sorts of problems in terms of stability, etc.
2- What problems will I face if I ground the -Vs of the opamp? I only have one lab supply...
3- Do you have a better idea?