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Looper's Delight
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"The circuit for a switch connected to the Footpedal jack is very simple. It is just a resistor and a momentary switch connected in series between the tip and sleeve of the jack. Pressing the switch connects the tip and sleeve together through the resistor. The Resistor values determine the function that the Echoplex executes. These switches can be in parallel, although if you press several at once you will get unpredictable results. (It is possible to press other switches while holding down Overdub, however). If you look in the EFC-7 pedal you will see that it is just seven switch-resistor combinations, all in parallel between the tip and sleeve of the panel mount jack. Simple.
1% metal film resistors should be used, here are the appropriate values:
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If you want to make your own feedback footpedal (or elbow pedal, or whatever), use a 20k ohm or greater pot. Linear taper is probably better, but log works too. The value and taper will change the feel of the pedal, so you may want to experiment a little. The feedback level is controlled by the amount of resistance between the tip and sleeve. Anything over 20k should be maximum feedback, anything down around 0 should be no feedback. Connect the potentiometer's wiper to the tip, and the sleeve to one end of the pot. (Make sure it's the end that lets the pedal operate in the direction you want.) Simple!"
At 7:39 PM -0800 11/24/08, Travis Hartnett wrote:Is that based on the value of the adjacent resistor?
Yep, that's the unit. A lot of times some contact cleaner will fix the problem before you need to actually replace the switch. Use a multimeter to check that the resistance off each switch is reliably the desired value.
(Rummaging through drawer to see if I still have a color code key anywhere.)
--
David Gans - david@trufun.com or david@gdhour.com
Truth and Fun, Inc., 484 Lake Park Ave. #102, Oakland CA 94610-2730
Blog: http://cloudsurfing.gdhour.com
Web site: http://www.dgans.com
Photos: http://www.flickr.com/photos/dgans
Music: http://www.cdbaby.com/all/dgans