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SexieWASD
07-21-2009, 08:23 AM
I am going to be using a prop to replace the various controls on a custom stratocaster. The part I'm on now is that I would like to be able to rewire the guitars pickups on the fly by switching on an off various transistors with the prop chip. I have the circuit for each pickup planned out I just don't know what to use for a transistor.

I have very little knowledge of basic electronics (I'm a fast learner). I've got a 2n-2222 (bi-polar) transistor switching a microphone on my breadboard, I seam to pickup a baseball game when it's not turned on, but that may have more to do with sending a microphone signal through a breadboard.

I need to know how I should choose the transistors to use. Is there anything wrong with using a bpj transistor and not a fet/mosfet for this application, I don't need the linear control, just a switch. Will I run into lots of RF noise running a less than 1V signal through multiple transistors?



sorry about asking a basic electronics question, but I'm lost on this one and didn't know where else to ask.

Phil Pilgrim (PhiPi)
07-21-2009, 08:33 AM
My inclination would be to preamplify each signal separately to "line" level and to switch the amplifiied signals. Not only will you eliminate a potential source of noise, but doing so should reduce any "popping" you hear when you switch sources, since the pops won't be preamplified.

-Phil

Leon
07-21-2009, 08:40 AM
Analogue switches like a 74HC4066 or a 74HC4053 would be a lot easier to use and won't demodulate radio signals.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

SexieWASD
07-21-2009, 08:47 AM
I think you are right about that being the best option, my only problem is that that it needs to be run from a 9v li-ion, I think I need to do some research on phantom power.


@ Leon

I don't have any experience using analog switches like that. Guessing from the pin-out I would supply power and ground, then if I'm using pins 1,2 , 5 (1Y, 1Z, 2E) If I apply power to 2E, 1Y and 1Z would connect?

If that's how it works than that might be an even better solution, something I wasn't expecting.

Post Edited (SexieWASD) : 7/21/2009 1:58:37 AM GMT

Leon
07-21-2009, 10:59 AM
Pins 1 (1Y) and 2 (1Z) are connected when pin 13 (1E) is high, and are disconnected when pin 13 is low.

A 9V supply is OK.

Leon

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle