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Circuitbenders Forum => Circuitbending discussion => Toys => Topic started by: bobfather2003 on August 26, 2008, 09:27:18 PM

Title: speak and spell lfo
Post by: bobfather2003 on August 26, 2008, 09:27:18 PM

hi all.
I'm pretty new to all this and was wondering if anyone has fitted a lfo to the speak and spell to control the pitch.
Ive seen a few on ebay for sale and want to try to fit one to mine.
i have made a simple lfo using a 555 timer but don't know where to connect it on the speak and spell.
any help would be most  appreciated.
thanks
Gary.

Title: Re: speak and spell lfo
Post by: computer at sea on August 27, 2008, 12:26:56 AM

The speak & spell actually has some points on there that you can connect to a pot for a pitch bend without an lfo.  Look towards the bottom of the machine on the left hand chip.  Somewhere around there is the base and then there's a pitch up point some place near by and a down point.  They're pretty well documented on the net, so you should be able to find photos.

Title: Re: speak and spell lfo
Post by: 3rdness on November 11, 2008, 11:17:35 PM

Adding an LFO to a pitch control is great because you can control the rate/depth of the pitch modulation.  Like a tremolo-y warble or slow waves of pitch jumping.

Casper Electronics has a great schematic for this:

http://www.casperelectronics.com/images/finishedpieces/speak-n-spell/Speak-n-Xbending/LFO%20schematic2.jpg

This was the first 555 LFO i built, and I've modeled a bunch of them off of this.  Great stuff.