LED Voltage Indicator

Discussion in 'General Electronics Chat' started by DanRilley, Nov 21, 2009.

  1. DanRilley

    Thread Starter Senior Member

    Jan 13, 2008
    107
    0
    Hi, I am using a potentiometer to modify a control voltage for an oscillator. I have a target voltage that creates a desired frequency, say 4.6V. I want to have an LED that turns on when the voltage is around the target voltage. My first naive idea was to just hook the LED from the control voltage to ground, but that drastically lowers the pitch since the voltage gets used to light the led. I assume I need some IC that could compare that voltage to a reference voltage without modifying the original voltage, could someone suggest one? I am using a single 6V supply.
     
  2. DanRilley

    Thread Starter Senior Member

    Jan 13, 2008
    107
    0
    OK I got a workable solution. I had an LM358 lying around. I know you're not supposed to use general OPAMPs as comparators, but If I create a voltage divider to create the reference voltage (finding perfect resistor combinations is very hard) and put it into the inverting side and then put my oscillator CV into the non-inverting side. An LED at the output will show if one is higher than another. This will work for now, but any better solutions could be cool.
     
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