From: john/lori (lgnjh_at_earthlink.net)
Date: 2007-04-21 13:39:29
Daniel O'Shea wrote: > I apologise, I wasn't intending to open up such a can of worms! As I > stated in my original post, I have a variable voltage of 0 to 5V (no > microcontroller involved) that I want to translate in to a variable > current using a transistor. And so, I am lead back to my original > question - what kind of transistor and what value would work best to > provide a variable current which duplicates the potentiometer's variable > current? and do I need any extra components besides just a transistor? > thanks! > > Message was sent through the cbm-hackers mailing list > After thinking about it a bit, here's what I came up with. I'm not optimistic about it's behavior, (non linearities and such). I didn't go so far as to breadboard it or even simulate it, it's just some doodling. No doubt it would have to be tweaked. I was figuring for 2N3906, 2N3904 but I doubt it's critical (any roughly similar transistors would probably do). Note there's an inversion, a higher voltage in would give a lower reading. +5V | +---------+ | | 3.8K 390 ohms | | | +----+ | V | 0-5V | |/pnp | IN o--13K--+--| | | |\ |/npn | +--| | |\ | V 18K +---o POT | _|_ /// gnd bogax Message was sent through the cbm-hackers mailing list
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