Circuitbenders Forum

Circuitbenders Forum => Circuitbending discussion => BENDING TIPS => Topic started by: Dylan on October 30, 2011, 03:13:44 AM

Title: Vactrols / removing LED con/off clicking
Post by: Dylan on October 30, 2011, 03:13:44 AM

So I've build a few vactrols, and everytime I do it, there's an audible click with every flash of the light. Can anyone tell me how to get rid of this click? Would put a resistor in series with the LDR help reduce that?

Title: Re: Vactrols
Post by: Dylan on November 17, 2011, 04:21:22 AM

Well I found something in my searches, and so no one posted anything I thought I might as well bump this thread to do so. This is for the initial "on" of a guitar pedal, but since my vactrol is just an LED going on and off I think it may just work. So check this out if you're having the same problemo as me:

http://www.muzique.com/lab/led.htm (http://www.muzique.com/lab/led.htm)

Title: Re: Vactrols / removing LED con/off clicking
Post by: Circuitbenders on November 17, 2011, 10:29:35 AM

nice one.  ;)

I've just edited the thread title to include LED clicking.

Title: Re: Vactrols / removing LED con/off clicking
Post by: Gordonjcp on December 06, 2011, 11:13:58 PM

The popping is caused by two things - there's a DC offset in the signal through the LDR side of your vactrol, and the edges of your light pulse are nice and square.

In the circuits linked in the previous reply, the resistor and capacitor act to give the LED a bit of an envelope, which should help.  Fiddling with the resistors and capacitor ought to give you something you can adjust to minimise the popping.  A better approach would be to try to eliminate the DC offset through your controlled circuit.

There *is* a reason why vactrols are seriously uncommon.