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Lessons Learned and When the Chips Are Down

Audioguru

Sep 24, 2016
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I corrected the tone control circuit so you can turn down the fizz.
The circuit designer did not know that C3 had its polarity backwards and also did not know that an opamp NEVER has a capacitor to ground on its output which happened if the original tone control was turned to produce no highs cut.
An opamp with a capacitor to ground on its output would have a phase shift causing oscillation at a high frequency at maximum power causing it to overheat. The 270 ohm resistor I added would be the minimum tone control resistance that you would not hear (27kHz is cut -3dB) and the opamp would be fine.
 

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Audioguru

Sep 24, 2016
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A metal ring terminal on top of the foil can be bolted to the box and connected to the circuit's ground (the negative battery terminal).
 

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WHONOES

May 20, 2017
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I should have mentioned that you should also connect the metal case of your potentiometers to the battery negative as well.
 

WHONOES

May 20, 2017
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You are right Harald. I should have said "connect to the foil".
 

SparkyCal

Mar 11, 2020
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I'm happy to report that I used the foil method, and it worked. The stomp box is a lot quieter now and sounds good. When i get a chance, i will record it and let you all hear it. What a difference using solder paste makes. Wish I would have done that since day one.

@Audioguru- I was too far into it, to incorporate your changes regarding adding the new resistor. However, I plan to build it again and this time, i will incorporate your suggestions.

Thanks to all!
 

bertus

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Nov 8, 2019
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Audioguru

Sep 24, 2016
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I haven't heard about Dick Smith's used car and electronic parts for years. Down Under student got parts and kits from him.
 
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