A 4- to 20-mA loop needs no external power source


Posted on Jul 9, 2012

The simple circuit in Figure 1 uses a low-current-drain MAX4073H amplifier to sense the current flowing through a 4- to 20-mA loop. The circuit senses the current through a 1 resistor with a fixed gain of 100 and uses no battery or dc power supply. The low current drain of the amplifier (0.5 mA) enables the circuit to tap its power from the 4- to 20-mA loop to power the amplifier chip. Note that the current flowing in the amplifier`s power-supply Pin 3 (nominally 0.5 mA but may vary slightly) is not part of the sensing loop.






Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Auto Fuse for power supply
Constant-speed-motor-driver
80 milliwatt Improved 3 Transistor Audio Amp
Factory Alarm
USB powered battery charger circuit
cool chip lt1970 power op amp with current limit
lights led circuits schematics
Simplified magnetic amplifier circuitry
A block diagram of AN6657 and basic application circuit
LM4819 audio power amplifier circuit
90 phase shifter circuit having a flat frequency characteristic
Practical three control delay self-extinguishing switch circuit schematics



Top