Vocal Processor
<img src="/images/finishedpieces/vp-01/vp-01_01.jpg" width="400" height="300" alt="casperelectronics VP-01" title="casperelectronics VP-01" />

This piece incorporates two different circuits.<br>
One is an echo, the other a <a href="http://www.casperelectronics.com/finished-pieces/megaphone/">voice changer</a>.<br>
Both are taken from children's megaphones. <br>
The echo circuit is very similar to the one found in the <a href="http://www.casperelectronics.com/finished-pieces/barbie-karaoke/">barbie karaoke machine.</a>
<img src="/images/finishedpieces/vp-01/vp-01_02.jpg" width="400" height="300" alt="casperelectronics VP-01" title="casperelectronics VP-01"/>

The VP-01 can be used as an FX processor AND as a sound generator. Both circuits generate noise when the pitch is lowered. The echo is especially noisey and creates pulsing blips and beeps at low pitches.<br>

<img src="/images/finishedpieces/vp-01/vp-01_03.jpg" width="400" height="300" alt="casperelectronics VP-01" title="casperelectronics VP-01" />
The layout is fairly straight forward.<br>
The input signal is split out to both circuits. There is also an adjustment for sending the echo into the voice changer.<br>
I rewired both circuits to add pitch adjustments and volume.<br>

I'm currently working on a new version of the VP01 built from scratch. I've found ICs very similar to those found in the megaphones.<br>
This model will be more versatile and reliable since it won't be built from modified children's toy circuits.<br>
The echo IC is the <a href="http://www.ortodoxism.ro/datasheets/PrincetonTechnologyCorporation/mXyzsyzt.pdf">PT2399</a>.<br>
<a href="http://www.geofex.com/PCB_layouts/Layouts/pt2399.pdf">Here</a> is a link to a schematic for building an echo pedal using this IC. <br> There are more schematics and PCB layouts floating around if you look.

The voice changer IC is the <a href="http://www.holtek.com.tw/english/docum/consumer/8950.htm">HT8950</a><br>
The only details I've found on this IC are the ones included with the spec sheet.