3pdt switch pop.

pnak · August 19, 2005, 07:51:26 PM

I know that this has been answered in other posts but I cant find it . It has something to do with soldering in a 1 meg resistor. Where and How?

gaussmarkov · August 19, 2005, 07:58:10 PM

often on the output, a 1M resistor to ground. you can put it across the lugs of the jack itself. no need to mess with the circuit. hope it works for you!

stankyfish · August 19, 2005, 08:17:52 PM

Quote from: pnakI know that this has been answered in other posts but I cant find it . It has something to do with soldering in a 1 meg resistor. Where and How?

What kind of circuit is it? Do you have a pulldown resistor after the input cap?

ninoman123 · August 19, 2005, 08:19:51 PM

If a pulldown resistor doesnt help then check the input/output caps. My TS-808 used to pop, and it had a pulldown resistor. One of the input/output caps was leaky so I switched it and no pops now!

stankyfish · August 19, 2005, 08:21:32 PM

Check this page.

stankyfish · August 19, 2005, 08:22:56 PM

Quote from: ninoman123If a pulldown resistor doesnt help then check the input/output caps. My TS-808 used to pop, and it had a pulldown resistor. One of the input/output caps was leaky so I switched it and no pops now!

Right -- if the cap is bad and the pulldown resistor is unable to handle the leakage of the bad cap, then you can get popping, too.

pnak · August 19, 2005, 09:03:18 PM

It is a mosfet boost. I never noticed the pop until I used it last night at my band practice and it popped a few times at first and diddnt seem to pop as bad as the night went on. Thanks for the info ill give it a try.

SirPoonga · November 17, 2005, 05:47:55 PM

Quote from: stankyfish on August 19, 2005, 08:21:32 PM
Check this page.

Is a 3pdt switch constitute number 3 on tha list? So nothing that can be done?

niftydog · November 17, 2005, 08:05:59 PM

if it's purely no. 3 on that list, you'd be hard pressed to hear it in most applications.

Usually it's no. 1 that is the main culprit.

no. 3 is talking about the signal itself, not any DC offset that may be present. That is, at some point the signal is at a positive voltage relative to the unconnected terminal of the switch. If you switch just at the exact right moment you may perceive this as a pop.

On a larger scale this can be incredibly dangerous. Like, imagine you're running a sub-station, and you need to switch from a main feed at 30kV to a back up feed for some reason. You don't wanna make that switch while either feed is sitting at +30,000V do you!? So, they employ special techniques to detect the point at which the voltages are at 0V, and that's when they switch.

Zero crossing has other less dramatic applications, such as in digital potentiometers. The idea being to avoid those little pops as much as possible so as not to generate "zipper noise" when multiple FETs are switched in sequence. Zero crossing solid state relays are common as well.

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3pdt switch pop.