Change Signal Voltage Range , rationally.

Discussion in 'General Electronics Chat' started by MarFene, Nov 6, 2015.

  1. MarFene

    Thread Starter Member

    Feb 27, 2014
    Basically i have a signal voltage , ( Minimum 0V , Maximum 5V) Coming from a simple potentiometer voltage divider , which i want to use to change the intensity of an LED (in a vactrol). the problem is that from 0v to 3v the LED does not light up. therefore i want to change the 0v-5v signal into a 3v-5v signal.

    one way of doing it might be to replace the GND in the voltage divider to a 3 volt potential. but i did not want to take this option.

    any idea on how this can be tackled?

    thanks in advance
  2. bertus


    Apr 5, 2008

    Leds are current contelloed devices.
    Changing the voltage ia a bad idea.
    You could use the 0-5 Volts signal to control a PWM generator.

  3. dl324

    AAC Fanatic!

    Mar 30, 2015
    To clarify. You're against adding a resistor in your voltage divider to restrict the pot to 3-5V?
  4. MarFene

    Thread Starter Member

    Feb 27, 2014
    actually now that i'm thinking about it .

    well let me explain , the voltage is coming from an 8 step sequencer ,each step with variable voltage output . since the output of this sequencer can be connected to several things ( Mostly using the full 0-5v range ) i do not want to modify the sequencer itself , but rather the part where there is the vactrol.

    but now that i'm thinking about it , i rather add a simple toggle switch changing the GND with 3.3v to the sequencer itself and flip it when the vactrol is connected