One downside of that design is when you use the power pin like that you have to use a dedicated part, which means you can't use it with quads and duals.
Re: current sink
Dec 21, 2023
Last reply: 2 years ago
6 Replies
I think this works.
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It might, if you picked the right op amp. Only a limited number work with their inputs at the negative supply voltage.
Until you identify the op amp, it's a less-than-useful insight.
Yes, clever - within the limits on range, compliance voltage and stability should work.
Fun!
Cheers
Phil Hobbs
My 1963 "Handbook of Operational Amplifier Applications" by Burr-Brown shows this current source:
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Regardless, your own variation is also interesting.
Danke,
Only bad ideas, but you do seem to produce a lot of them.
Sure you do. But you could (and should) have been more specific about which op amp you had in mind.
Nobody gets paid for reading usenet posts. Sometimes it is an educational exercise, for some people - not you, obviously - and thus an investment.
You use an op amp to monitor the current going through the jfet, and let the op amp output adjust the gate voltage to get the right current.
You do need to design the circuit so that the op-amp output can swing far enough to cope with the worst case jfet - at either end of the range
- but that's just worst-case design, and most of us seem to know about that.
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