Electronics > Projects, Designs, and Technical Stuff
Just another DC Load
henmill:
I finally got around to turning this thing on again.
I decided to pick some values and hold my breath and see what happens. Rather than list them out, here is a schematic view showing the nominal values of what I have on the board today:
edit: maybe it goes without saying if you've been reading, but this schematic does not show my actual FET part number.
At a glance, it is functional at least. I didn't have much time tonight but I probed around a bit and ran a couple quick tests.
First, I just wanted to watch the sense node and gate to look for any weirdness. Perhaps I found something of interest, but I'm guessing it might be the ripple from the power supply "under test".
In the waveforms, channel 1 (yellow) is the sense node/Source.
In this waveform, the setup was running at 15V in, 2A. Channel 1 is AC coupled and you can see the sawtooth shape at the sense node. Channel 2 (blue) is the gate. It seemed steady enough, though maybe I should have looked more closely to see if the same frequency is present at the gate. 35mV pk-pk doesn't seem like much, but when a 1A set current should be 100mV, that is quite a deviation. The amplitude seemed about constant as I moved up and down in current.
I decided to get crazy and try a quick "hot plug" test at 10V 1A. In this capture ch1 is the sense node and ch2 is at the Drain. For this test I had the unit running at 10V, 1A. Then I disabled the power supply and unplugged the + wire. Then I turned on the power supply output and plugged it in.
Here are also a couple pictures of the hardware.
Thanks as always for feedback, and if anyone wants to suggest a test plan, I'd welcome it!
RoGeorge:
Nice build! :-+
(May I kindly ask you next time to embed inside the text full size pictures, please, and not their thumbnail, because the thumbnail opens in a new tab, so it's bamboozling to go back and forth between the text and the picture tabs.)
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