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DIY Stompboxes => Building your own stompbox => Topic started by: dschwartz on December 18, 2007, 07:26:39 AM

Title: has anyone tried this??
Post by: dschwartz on December 18, 2007, 07:26:39 AM
Hi all!!
I was thinking about creative ways to amplify or effect a signal..
It came to my mind the idea of using a LDR as a transistor, since it varies the resistance across it depending on light...

The concept is to use an opamp to drive a led, and the led acts like a gate.., the LDR has the drain and source and could be used as a transistor..

has anyone try this? i tried simulating it on livewire, it kind of worked..but i would like to know how it will sound..
I´m not really a friend of proto boards  :icon_lol:
Title: Re: has anyone tried this??
Post by: Seljer on December 18, 2007, 04:14:42 PM
LDRs are slow, really slow, as in not fast enough for audio
Title: Re: has anyone tried this??
Post by: David on December 18, 2007, 04:39:09 PM
Quote from: dschwartz on December 18, 2007, 07:26:39 AM
Hi all!!
I was thinking about creative ways to amplify or effect a signal..
It came to my mind the idea of using a LDR as a transistor, since it varies the resistance across it depending on light...

The concept is to use an opamp to drive a led, and the led acts like a gate.., the LDR has the drain and source and could be used as a transistor..

has anyone try this? i tried simulating it on livewire, it kind of worked..but i would like to know how it will sound..
I´m not really a friend of proto boards  :icon_lol:

Look at the Flatline compressor.  The gain string has a LDR as a variable element, i.e. darker=more gain.
Use it as a resistor, not a transistor.
Title: Re: has anyone tried this??
Post by: dschwartz on December 18, 2007, 04:45:32 PM
i know, i know...
Ldr´s are slow...they´re used in compressors like flatline and dod 280...

but maybe an interesting sound can be achieved using it as i did..maybe percussion like? a low pitch noise? a delayed muffled sound?