crackle box with line out LFO leakage

Discussion in 'The Projects Forum' started by Adamt5000, Apr 6, 2013.

  1. Adamt5000

    Thread Starter New Member

    Nov 24, 2012

    I've been building a crackle box with an astable 555 timer used as an LFO. the circuit works fine with the built in speaker and with headphones plugged in, but when I hook it up to an amp I hear a quiet version of the crackle box when the 555s output is low. The output of the 555 is hooked up to the base of a transistor that then pulses the output of the crackle box. My question is what do i need to do to get a good line out signal with no leakage between LFO pulses?

    This is my first (successful) build and my knowledge of electronics is very basic, so any suggestions are welcomed. i dont have a schematic but I could whip one up if need be.


    Adam T
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    It's a common problem with audio switching that the switching OFF mode is not perfect and the amp has enough gain to hear the very small leakage coming through even in the OFF mode.

    You can improve the switching by using a better switch, like a relay, or you need to improve the transistor switching you already have.

    If you show a schematic we can advise better. Please do so! :)

    Just as a first guess you can probably use two transistors, one to disconnect and one to short. That should work a lot better than just using one transistor to short the signal.