[sdiy] semi-beginner's op-amp question

[Harry Bissell Jr]

I'd say that was a job for a transistor, IMHO.

If you are driving a vactrol, control of current
is probably the way to go.  I'd check out some
4-20 (or 0-20) ma current loop circuits for ideas.

One popular way uses a sense resistor and the opamp
drives the transistor on until the feedback is
satisfied.

iirc National Semi and Linear Tech have app notes
about his

H^) harry




--- Kevin Lightner <synthfool at synthfool.com> wrote:
> Not to hijack this thread, but I have a small opamp
> question also.
> 
> What is a good choice for an opamp for driving a
> long run of wire?
> Dual opamp/single supply desired, but (like many
> people) could go 
> bi-polar or use two.
> Mostly to be used as a DC follower/driver.
> Wire is about 22ga, solid copper, unshielded. Load
> is basically a 
> vactrol: not very picky, but about 30 ma or so, max.
> Obviously the 
> wire adds up to something also in resistance and
> capacitance, but 
> it's overall not a very precision circuit.
> Maybe many opamps would work, but from the general
> "you probably have 
> these in stock" types, what would be best?
> 
> Thanks for any input. :)
> 
> -- 
> Regards,
> Kevin Lightner
> 
> Myself: http://www.synthfool.com
> Service and sales:
> http://www.moogmusic.com/service.php
> Sales: http://www.cluboftheknobs.com
>