<a href="http://www.casperelectronics.com/images/finishedpieces/BOSSds-1/S3600038.JPG"><img src="http://www.casperelectronics.com/images/finishedpieces/BOSSds-1/_S3600038.JPG" width="400" height="300" alt="" title=""  /></a>
<strong>The photo above shows two switches. One is illustrated below, the other is not very good, so I didn't include it in the illustration</strong>.

<p>
This page shows how to install a gated feedback effect. It's a really great sounding effect. Sort of ringmod meets harmonic exciter of some sort.<p>
<strong>What is feedback</strong>?<br>
 Basically feedback is where the audio signal from somewhere along the signal path is fed back into an amplifier stage somewhere EARLIER in the path. This creates a feedback tone and can result in some really nice sounding, rich tones when an incoming signal fights with the feedback tone.
 <strong>The problem with feedback</strong> <br>
is that when there is NO incoming audio signal, there is just steady, squealing tone.
<strong>Gated Feedback is the solution</strong><br>
I wanted to find a way to make the effect happen only when there was sound feeding into the pedal, so that when you aren't playing into it, there's no sound output.<p>
A <strong>transistor configured as a gate</strong> is the answer. I experimented with some transistors configured different ways and found the 2N3904 NPN to be the most effective.<br> <strong> I encourage people to experiment with different types of transistors</strong>.<p><h2>PLEASE READ!!!<br>
In the drawing below, the yellow wires and purple and blue wires are the same mod! I photographed the circuit board after I had installed the mod switch. It's impossible to see how the purple wires connect to the transistor and switch, so I drew yellow wires to illustrate how to wire everything. Ignore the purple and blue wires! </h2> <br><a href="http://www.casperelectronics.com/images/finishedpieces/BOSSds-1/BOSSSSDS-1.jpg"><img src="http://www.casperelectronics.com/images/finishedpieces/BOSSds-1/_BOSSSSDS-1.jpg" width="300" height="400" alt="" title=""  /></a><br>NOTES:<br>- The distortion knob controls the effect.<br>
-I soldered the transistor to the component side of the board so that I could still close the back cover. The back cover presses right against the solder side of the board so there's no room to add components.