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LM386 Question? Answered

How critical is the .05uf capacitor in this diagram?
Can a .1uf capacitor be used instead?
I know the 250uf electrolytic capacitor can be replaced with 220uf for coupling, but not sure what effect using a .1uf in place of the .05uf would be?


The caps in this schematic are not of the normal values you can find. In another answer I said to use 220 uF for the output because 250 uF is nonstandard. Anyway, the .05 uF and the 10 ohm resistor are there to prevent oscillation, commonly called motorboating because of it's similar sound. You could try using the .1 uF and see how it affects the sound (see steveastrouk and verence). If you have 2 of them, place them in series to get .05 uF (capacitance is the reverse of resistance when it comes to series and parallel). You might even be able to find a .047 uF cap that would work. When it comes to those values, the tolerance is pretty loose.

Also, the PDF says that the barebones version doesn't use these, but they should be added if you get oscillation.

Good luck with your LM386!



6 years ago

Two o.1 uF caps in series equal a single o.05 uF...



6 years ago

Yeah, what they said... ;-)

You're not substituting a cap with a huge difference here. And with capacitor values often varying by +-40%, a cap labeled 0.1 uF might be close to a 0.05uF labeled cap anyway (or further --it's guesswork without a capacitance meter). In other words, a stock 0.05uF cap might be 0.08uF--and the circuit would operate just fine.

You can tune the low-pass filter additionally by altering the 10 ohm resistor--you can lower the effect of the 0.1 cap by increasing the resistor to 12 or 15 ohms...

Use a 220uF coupling cap for less bass response, or a 330uF for greater bass response...

Did not try it, but a bigger capacitor will cut the high frequencies a bit more. As steve said, just try it.