I'm working on designing a voltage controlled filter, and in order to control some other components, I designed a little transistor circuit like this:
and so far, I'm actually pretty impressed with how it works. The control over the output current seems pretty linear, and the transistor is biased somewhat okay. From what I've played around with, I've found that changing the resistor just above the collector will change the overall sensitivity, changing the emitter resistor changes the minimum/maximum output current, and changing the base resistor does pretty much the same thing as changing the emitter resistor. You can play around with it on Falstad's circuit simulator.
I could use some criticism on it from more experienced engineers. Also, if this circuit's been made before by someone else, that would be cool to know.
and so far, I'm actually pretty impressed with how it works. The control over the output current seems pretty linear, and the transistor is biased somewhat okay. From what I've played around with, I've found that changing the resistor just above the collector will change the overall sensitivity, changing the emitter resistor changes the minimum/maximum output current, and changing the base resistor does pretty much the same thing as changing the emitter resistor. You can play around with it on Falstad's circuit simulator.
I could use some criticism on it from more experienced engineers. Also, if this circuit's been made before by someone else, that would be cool to know.