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Current Controlled Resistor

S

Stretto

Jan 1, 1970
0
http://tinypic.com/r/vy723d/7

I was just playing around and came up with a rather stupid CCR. As you can
see the base current modifies the slope = effective resistance. The IV
characteristics seem fairly constant. The resistances range from about 5k to
300k which easily can be changed by modifying the resistor values.

I'm sure the circuit can be simplified and optimized... anyone care to give
it a try? Seems like it might be possible to use some form of circuit
topology to get a nice VCR and/or CCR that works over a wide ranges of
voltages, currents, and resistances that an be floating.

I haven't found anything but JFETs for VCR's and they tend to have small
resistances(max I've seen is about 10k) and cannot be "floating"(at least
not without more complexity/cost).

I did find

http://alokgovil.com/Professional/Projects/Analog/Current-Controlled-Resistor/CCR-Document.pdf

for a CCR that supposedly has a wide functioning range of parameters but
seems a bit complex and costly. I'm looking something, not a digital pot,
that can replace a pot... or rather be controlled by a pot as I need a
single pot to control multiple sites.

Of course I have no clue if the circuit in I came up with actually works.
Just did some IV analysis on an idea and played around with it until I got
slopes that dependent on the base current. So please no flames...
 
J

John S

Jan 1, 1970
0
On Sat, 11 Jun 2011 06:37:31 -0500, John Fields

On Fri, 10 Jun 2011 15:41:11 -0700, John Larkin


Building a real, floating, programmable resistor, with volts of swing,
isn't easy.

---

.[DAC]---[LED]--> [LDR]

That will work, but LDRs are pretty weird and drifty things, not very
quantitative.

Denying? I said they were weird and drifty, which they are.

Crabby again, I see.


Use your imagination once in a while. You probably have one, hidden
away and seldom used, but maybe still there.

His weenie fixation getting in the way, maybe?
 
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