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Author Topic: A question about adc converting  (Read 2062 times)
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sphinx
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« Reply #25 on: August 18, 2019, 04:23:25 04:23 »

@ sideshow bob i did desolder the pcb so you can do a reverse engineer it to the same pcb and i did some scans of that all i got is in that collection
i have use this psu since i built it and it was made with connecting to a computer/embedded when it was designed.
i have repaired it several times from what i can remember it was the output transistors that went byebye
last time i repaired it i lost a piece of wire in it while powered on and some tracks burnt but it was fixable with
output transistors some fixings of the tracks.

once i forgot it on for a week with load on so cooling was pretty darn hot, no worries it still worked after that.

there is a tiny capacitor on one opamp ic's  i think one missing caused oscilation

i have never measured how good it really is.

it is also buildabable in single rail version as well all info in the scans.

no worries wizpic more input is hopefully better.

/sphinx
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Wizpic
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« Reply #26 on: August 18, 2019, 05:44:01 05:44 »

Looking at the PCB where the extra cap is on IC1, My schematic I've already added that cap and it says 47pF ?
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Sideshow Bob
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« Reply #27 on: August 18, 2019, 06:12:49 06:12 »

What you can do is to measure the voltage over the current sense resistor as the this voltage will have a linear relationship with the output current. But you have to ground reference this voltage and apply some gain to this volage so it fit your ADC range. If you look at the datasheet for LM324 http://www.ti.com/lit/ds/symlink/lm324-n.pdf  
You can use figure 32 or 38 for this. Any single supply OPAMP can do the job here as long as you stay inide the input Common-Mode Voltage Range given in the datasheet and of course also the supply volage. That will be the same as IC1 and IC4 use. If you want to measure the negative rail with the same micro controller this voltage will need to be inverted
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sphinx
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« Reply #28 on: August 18, 2019, 06:17:57 06:17 »

yes that is right. it is a 47pF
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