waltr wrote:Yea, they are not that readily available any more. Internally they are basically a n-ch JFET and a resistor. +V on the Drain, resistor on Source to -V with the gate also to -V (see "Art of Electronics" or a google search).
Another method is a constant source (or sink) using a BJT, two silicon diodes and a resistor. The LM317 constant current configuration also works well.
It just depends on what you really need the constant current for. Do remember that these circuits try to maintain a constant current and vary the voltage to do this. They are not the best for a current limiter with a constant voltage.
plumber wrote:Thanks waltr and wiml,
Yep. I'm lost. As I get closer to a working solution...I lose it when trying to specify values in the parts search engine provided by online suppliers. I went to mouser and got beat up trying to find the right parts...I'm just not learning fast enough. So whats up with packaging/case ? I'd be using a bread board. So yes, any prototyping help would be great...I swear I'm hooked on this stuff, but for the time I have right now, my brain ain't going quick enough.
Thanks again, plumber
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