Voltage-to-current converter

The converter proposed here (also called voltage-controlled current source) is based on just one opamp, and provides to, or draws from, ground a current that is dependent on its input voltage. The unit can con- vert negative as well as positive voltages into negative currents (from ground) and positive currents (into ground) respectively. When a Type 741 or CA3140 is used in the Al position, Rv =1 k, and R =10 k, Um = +10 V max.; Io = ±20 mA max.; and gm=-1 mS. It is, of course, possible to change any or all of these values as required by using a different opamp and alter- ing the values of the resistors. The maximum output current is always dependent on the opamp used. To make such changes, the following formulas may prove useful. U+ =U- = (Um-Uout)/2+Uout = 1k R = 10k IC1 = 741/CA3140 U,, = max.±IOV lout= max.±20mA lout/Um = -1mA/V 86435-1 voltage-to-current I 1 01 converter U0=2[(Utu-Uout)/2+Uout]=Uin+Uout IRv = Uin/Rv Tout= IRv ± IR = Utu/Rv+(Um-Uout)/2R If R>>1t...