:: ghetto PMOS current control

in trying to re-purpose 2 of my used DPAK PMOS, i thought just throw them into a sub circuit module to do some wide range variable current control.
and after some general "thermal camouflaging".The controller in this test setup is powered from 20VDC. this test is feeding a 3.3v. due to the biasing and help of a 10turn pot, it is able to accurately reverse power the zener anywhere. the current is so low (uA) the APPA meter is unable to read it proper
here in the video, the APPA/UNI-T is swapped around. the UNI-T with uA scale is able to measure the micro amperes. it is interesting to see that with a 10 turn 1k bourns, the amount of current is very easy to control. no kidding, controls down to 0.1uA it seems, even with the uncertainty in the last digit of measurement accuracy, we can see from the arbituary "movement" of the current going thru from that start @ 0.1uA onwards. although it would be tough to justify how i could use 0.1uA, still it goes up to 4.5A. in the setup the temporary control module has 2 metal clothes pegs clamping the brass tag to a heatsink. the aluminium clothes pegs are a random find on taobao, it was a definite buy. 1) it can serve as cable grounding retainers 2) temp heatsinks, 3) PCB work clamps ... etc. unlike expensive sold as electrical accessory pegs or clamps or croc clips, these are really cheap and useful.


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