Saturday, April 13, 2013

Voltage to current converter with floating load


          The current in the feedback loop depends on the voltage and Ri.
This applications where we need to pass a constant current through a
load and hold it constant despite any changes in load resistance or load
voltage. When the load does not have to be grounded, we simply place
the load in the feedback loop and control both input and load current  from this circuit.
          
This circuit shown in figure voltage to current converter
with floating load. The voltage to current converter can be used in
such applications as low voltage dc and a voltmeters, diode match
finders light emitting diodes (LEDS) and zener diode tester.

         This circuit diagram Figure shows a voltage to current converter in which load resistor RL is
floating (not connected to ground). The input voltage is applied to the
no inverting input terminal and the feedback voltage cross R1 drives the inverting input terminal. This circuit is also called a current series negative feedback amplifier because the feedback voltage across 1 (applied to the inverting terminal) depends on the output current i0 and is in series with the input difference voltage vid.