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LM386 opamp Module, measuring amplified output without giving it input

JimB

Super Moderator
Most Helpful Member
Possibly due to the small leakage current through the output coupling capacitor.
This is nothing to worry about.

JimB
 

alec_t

Well-Known Member
Most Helpful Member
If the input terminals aren't connected to an intended signal source then they will pick up stray signals from the environment. Mains interference is a common culprit.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Hi. I am using an LM386 opamp Module from Amazon. I am powering it with a 5V input (just to power it, not intending to amplify anything at this point). Nevertheless a multimeter measures an amplified output of around 1v-2v.
Well first off, it's NOT an opamp module, it's a small power amplifier module - if you want an opamp, then use an opamp.

Secondly, don't stick a multimeter on the output - it's completely meaningless, and won't give any useful indication at all.

Stick a small loudspeaker on it (as it's intended for) and see what you can hear.
 

Arjuna_1000

New Member
Well first off, it's NOT an opamp module, it's a small power amplifier module - if you want an opamp, then use an opamp.

Secondly, don't stick a multimeter on the output - it's completely meaningless, and won't give any useful indication at all.

Stick a small loudspeaker on it (as it's intended for) and see what you can hear.

Thanks. I connected a speaker to it as you suggested and it worked. Then I was actually able to measure the voltage change as I intended in the first place.
 

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