Electronic Circuits and Projects Forum



ericgibbs

4mA thru 20mA Loop to 0V thru +5V Converter

by ericgibbs , 7th May 2012 at 12:08 PM (2728 Views)
hi,
This is a simple circuit for converting a 4mA thru 20mA Loop signal to 0V thru +5V, suitable for an ADC input.

When using a LM358 OPA, the closest specified lowest swing is approx 20mV above 0V.

Take care when using with a ADC that will not accept excessive outputs voltages from theLM358.
For example with a PIC if the OPA output could exceed 5V in operation, using a limiting resistor, that will limit the ADC input current to less than ~10mA.
The internal clamp diodes of the PIC are rated at ~20mA max.
A series 470R connected between the LM358 output and the ADC input pin will limit the clamp current to ~10mA, if the OPA output reached +10V.

NOTE: 16 May2012
Added a 0V to +10Vout version of the converter

NOTE: 17 May2012
Added a 0V to +5/10Vout version of the converter for a 0mA to 20mA input.
Attached Thumbnails Attached Files
Categories
General Purpose Circuits.

Comments

    Hi, Neat circuit. Would it be possible to modify the circuit to give a 0 thru 10V output. For your circuit, I guess another alternative would be the RCV420 IC.
    hi korak,
    As requested a 10Vout version has been posted.

    E.
    Dear Eric,
    Thanks for the quick reply. These circuits are really neat. The beauty lies in the simplicity with which you have achieved the conversion. I will try them at the earliest.
    Keep up the fantastic work
    Korak
    Nice circuit
    Hi Eric,
    I agree all reply here.
    There are more informations about LM358-serials just click here.
Electronic Circuits  |  Learning Electronics

Join our community with over 100,000 Members! It's free, easy and when you're logged in you have many more features! Click to register.
Page Time: 0.05044 seconds      Memory: 7,899 KB      Queries: 25      Templates: 0