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Old 07-08-2021, 03:11 PM   #45
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Join Date: Dec 2013
City & State: San Antonio
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Line Voltage: 120v 60hz / 240v 60hz
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Default Re: Signal Tracer - Requesting input on requirements

Originally Posted by clearchris View Post
So my options seem to be:
1. Shielded cable for the pot (do I ground the shielding?)
2. Shorten the pot cables to the point I'll have to completely redesign the case
3. Take the 10uf cap out to reduce the gain to 20x instead of 200x.
I shortened the cables on the pot to around 1 inch, no change in noise. Then I took out the 10uf cap to change gain to 20x instead of 200x, replaced the 1M pot with a 10k pot and bypassed the 4R7 resistor. Still noise.

Originally Posted by clearchris View Post
Also, I noticed that all the other LM386 noise filters on the output have the cap first, then the resistor connected to ground, yours is the only one I have seen that has the resistor (R3 10R) first and the cap (47uf) attached to ground. Does the order matter here?
Unless this makes a difference, I'm going to have to rebuild the circuit on perfboard or get a different amp. I think I'll get both the perfboard and a new amp on order and see which I can get working faster.

Does anyone have a suggestion for a more user friendly style amp module? Even if I don't use it myself, when I release the design, I'd like to have a more friendly option available, I'm not sure I would recommend the LM386 to anyone else unless they really wanted the challenge to level up their skills.
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