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Created April 06, 2013
Last modified April 06, 2013
Tags constant-current-source   currentsink   opamp   transistor   volt-to-current-simk  


Opamp and transistor used to convert a voltage to a current. The voltage to current relationship can be tailored using the following formula:

I = Vc/R1

Set R1 to a value that will produce the desired maximum current for the desired maximum voltage input.

V2 can be set as low as Vc_max + Vcesat + Vrload_min. If using a different OpAmp, make sure it's input common mode range includes ground or if not, then use a split supply (i.e. instead of connecting the opamp V- terminal to ground, connect it to a negative supply).

BTW: Rload is a place holder for whatever device needs to be current controlled (i.e. the current sink output is at the collector of Q1).


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