Loop powered 4-20 mA transmitter
Loop powered 4-20 mA transmitter
(OP)
I need help!!!!!!!!!!!!!! I am struggling with the idea of designing a loop powered transmitter. I have the circuit designed for the V-I transmitter portion, but I need power for the op-amp IC I am using. I know I can get this required power from the 4-20 loop, but how without effecting the signal? Any help would be greatly appreciated.





RE: Loop powered 4-20 mA transmitter
The idea is that the nominal total internal operating power consumed by the transmitter will always be less than 4mA. The transmitter feedback amplifier then deliberately forces more current than that, to set the actual real final loop current.
The feedback amplifier is then scaled to set the loop current to 4mA at zero input signal, and 20mA for maximum full scale input.
RE: Loop powered 4-20 mA transmitter
4mA x Vacross transmitter.
RE: Loop powered 4-20 mA transmitter
RE: Loop powered 4-20 mA transmitter
(voltage)-- add a resistor in line, and power a
DC-DC converter.
A few years ago, I would never have considered
this; I always used an extra pair to power the
remote. :)
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RE: Loop powered 4-20 mA transmitter