Voltage to Current Converter

An operational Amplifier IC LM741 used as a voltage to current. It is used for signal transmission of instrumentation like RTD THEROCOUPLE single from long distance to control circuits. Two type of current converter are.,

• Floating load Voltage to Current converter.
• Ground load Voltage to Current converter.

Floating load V to I converters are used as low voltage ac and dc voltmeters, diode,LED and zener diode testers. Voltage  to current converters Grounded load are used in testing such devices as zener and LED  forming a ground load.
             Float Load V to I converter Circuit.
 
Formula: Floating load:- V – I converter.
V_in = V_id + V_f  where V_id  is input difference voltage and V_f is the feedback voltage
But V_id = 0
V_in = V_f = R₁R_L
I_L = V_in/R_L
 

• Give input voltage to the non-inverting terminal of 741 and vary the input voltage.
• Measure the ammeter reading for various values of input voltage.

Ground load V to I converter.
 
 

Formula: Ground load V – I converter.
I₁+I₂=I_L
(V_in-V₁)/R+(V_o-V₁)/R=I_L
V_in+V_o-2V_i=I_LR
Since op-amp is non inverting
Gain=1+(R/R)=2
Vo=2Vi
V_in=Vo-Vo+I_LR
I_L=V_in/R
 

• First switch on the op-amp dual power supply.
• Give input voltage to the non-inverting terminal of 741 and vary the input voltage.
• Measure the ammeter reading for various values of input voltage