Products > Test Equipment
ET5410 Electronic Load mod: add external sense
cybermaus:
Ok, I opened it and added the diode(s) as in the picture
It will clamp reverse polarity to 0.6~1.0V depending on the input. (I tried up to -20V)
(images 1 & 2)
Also, I added 2x 1n4148, because the small leakage of the diode would affect precision a tiny bit.
And according to the 1n4148 datasheet while up to 5uA max, from the graph you see it is more between 10~100nA, dropping really fast if you stay away from the 75V max rating.
(images 3 & 4)
So by putting 2 diodes serial, we stay nicely away from that.
Not that anyone who buys this C brand would ever truly need that precision.
end0101:
looks good, I was going over the unit that delivered couple days ago (mine was made jan 2021 and looks like they omitted ps2 port), and some of my igbt legs and copper bars have some of the worst joints/pin not being seated, or outright they skipped out on soldering entirely, may wanna check the joints at top and bottom on copper and igbt legs
edit: think a 1N3595 low leakage from On Semi (digikey has 1N3595TR on cuttape for 0.24 us cents ea or 10 for 2usd) would be the ideal diode? low forward @10ma (0.65-0.8 ), 150v peak, 1na @125v reverse leakage, not really doing high speed switching to need the 4ns unless I am forgetting something?
cybermaus:
--- Quote from: end0101 on April 26, 2021, 05:41:41 pm ---I think a 1N3595 low leakage from On Semi (digikey has 1N3595TR on cuttape for 0.24 us cents ea or 10 for 2usd) would be the ideal diode? low forward @10ma (0.65-0.8 ), 150v peak, 1na @125v reverse leakage, not really doing high speed switching to need the 4ns unless I am forgetting something?
--- End quote ---
With 1nA 150V it would surely seems like a better option.
And I see no other problems with its specs, other then the fact you would need to special order them.
But still I think the 1N4148 is quite good enough for this purpose, especially as you (presumably, like everyone else) already have those lying around.
So it is all your own choice.
And before you value my ideas about all of this: I am only a hobbyist, I am not even sure the OpAmp even needs protection.
The TL072G OpAmp specs do list -0.5V absolute max common voltage, but also -10mA (so reverse) input current.
I just got it in my head that now the sense lines are separate, so I could make the mistake of hooking them up wrong, and I guessed the diode does not make it worse (ignoring the tiny leakage current)
BTW: I did hook up the main current inputs wrong once for a handful of seconds, and it shorted out the CC power supply, but both survived.
gico750:
Hi, I buy from aliex a ET5410, please could you explain to me why you need the modification and bring the thin wires on other bushings? thank you
gico750:
I mean the sense wires which have been placed centrally with two bushings
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