Electrical Engineering ⇒ Topic : Voltage to Current Converter

Peter
 
Voltage to Current Converter Figure (a) shows the schematic diagram for converting the voltage to current in which load resistance R_{L} is floating, i.e., neither side grounded. In this case, the circuit provides a current proportional to the voltage signal.
figure (a) Voltage to current converter The voltage gain A_{ν}, is very large for OP Amp, V_{i} = O. Therefore, it can be written as: V_{S} = V_{f} = R_{1}I_{L} ........... (1) Equation (1) represents the load current /L through the load resistor R_{L} at output. The input V_{s} in this case is converted into an output current V_{s}/R_{1}. So it can be said that the input Vs appears across R_{1}. The output current I_{L} = V_{s}/R_{1} can be fixed precisely when R_{1 }is a precision resistor. If the load R_{L} is grounded, the circuit shown in Figure (a) should not be used. The schematic diagram in this case is shown in Figure (b) where one side of load resistance R_{L} is grounded
Figure (b) Voltage to current converter. Applying KCL at node x, I_{1} + I_{2 }= I_{L} _{} .............. (2) From Eq. (2), the load current depends on the input voltage V_{S}, and resistor R. The load resistance should be less than or equal to R for satisfactory operation.  
 
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