Help with Current Sink

RichardJones · 31st January 2002, 04:37 PM

Ok, I am trying to make a current sink using a IRFP140N MOSFET. It is conected to -12v.

The amplifier is a IRFP140N in follower mode, with a IRFP140N underneath as a current sink.

Is it easier to have the current sink track the output voltage offset to minimize to zero, or have the bias on the upper MOSFET change to minimize output offset?

In either case, are there simple circuits out there that automatically adjust to minimize output offset?

On the other hand, I may not have a problem with offset and use a 2N2222 and a low value voltage sensing resistor around the lower IRFP140N to set the current level. Then I just adjust the upper IRFP140N to minimize offset..... all this done after the temp. has stabilized.

Help would be much apprecited!!
tia
Richard

dlharmon · 31st January 2002, 04:52 PM

I think you could use the current sink described in this thread.

Pass Son of Zen w/current sources (etc.)

Darrell Harmon

31st January 2002, 04:37 PM	#1
RichardJones diyAudio Member Join Date: Jan 2002	Help with Current Sink Ok, I am trying to make a current sink using a IRFP140N MOSFET. It is conected to -12v. The amplifier is a IRFP140N in follower mode, with a IRFP140N underneath as a current sink. Is it easier to have the current sink track the output voltage offset to minimize to zero, or have the bias on the upper MOSFET change to minimize output offset? In either case, are there simple circuits out there that automatically adjust to minimize output offset? On the other hand, I may not have a problem with offset and use a 2N2222 and a low value voltage sensing resistor around the lower IRFP140N to set the current level. Then I just adjust the upper IRFP140N to minimize offset..... all this done after the temp. has stabilized. Help would be much apprecited!! tia Richard

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31st January 2002, 04:52 PM	#2
dlharmon diyAudio Member Join Date: Nov 2001 Location: TN, USA	I think you could use the current sink described in this thread. Pass Son of Zen w/current sources (etc.) Darrell Harmon