Josh Koffman wrote:

> I was also intrigued by the current sink idea Phil proposed. I think I
> understand the idea (using the LED string to drop the voltage). Again, I
> have no experience with these, so please don't think too harshly of me
> for these questions. Would I just use an opamp current sink circuit
> between the end of the LED chain and ground? Does such a thing exist for
> high currents (7-10 Amps)? I'm having issues trying to find an example
> of something like this.

You usually add an output stage to the opamp that can handle the max
voltage and current you are designing for. In its simplest form, you just
add a transistor to the opamp output.

Look at the National site for opamp app notes; this is a standard
technique. There probably even is a circuit for a high-current current
source somewhere in their circuit collections.

Gerhard

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