Voltage Divider for Monitoring a circuit

Discussion in 'The Projects Forum' started by NRGeff, Apr 13, 2009.

  1. NRGeff

    Thread Starter New Member

    Apr 13, 2009
    Hello All,

    What I'm trying to do:
    Monitor (data log) a 0-24 volts control signal from a piece of industrial equipment.

    Problem: my data logger only reads 0-2.5 volts

    Solution?- Build a voltage divider circuit to step down the 0-24 volts to 0-2.5 volts. I read the sections on DC voltmeters and effects on the circuits being monitored.

    Question: How do I make sure my voltage divider circuit dose not effect the control circuit I'm monitoring?
    Just use resistors in the Mega-ohm range? Is there a way to know how big the voltage divider resistors should be?

  2. pilko

    Senior Member

    Dec 8, 2008
    How much the voltage devider affects the control voltage,not only depends on the resistance of the devider but also on the internal resistance of the control voltage source.The higher the source resistance,the higher the devider resistance required.Try a devider in the 10K range,if the devided voltage is correct,then you can lower the devider resistance.You may need a low devider resistance so as not to affect your final circuit.