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Author Topic: Battery Draining When Amp Turned Off  (Read 254 times)

thevargi

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Battery Draining When Amp Turned Off
« on: January 18, 2020, 06:40:43 PM »
Hi, folks.

I've been successful at building a few basic 9 Volt battery operated lm386 amplifiers, but I'm really a complete newbie and feel like I've lucked into being successful rather than because I have any real knowledge or skill. I say this because a few of my amps end up draining the battery when they're turned off (while a few have not). I know I must have a short somewhere, but I don't really know how to test for such a thing. Can anyone tell me how to test for a battery drain?

I'm using a standard, mono, unswitched 1/4 input jack, a toggle switch for power control (sometimes an on/off, sometimes an on/off/on just wired with two wires) and an output speaker.

Anyway, like I said. I'm a complete newb, and I don't know where to start testing (I can use a multimeter, so there is that at least!).

Thanks in advance.


Loudthud

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Re: Battery Draining When Amp Turned Off
« Reply #1 on: January 19, 2020, 12:50:16 AM »
Unsnap one side of the 9V battery and rotate the connector so that the unsnapped side isn't touching the battery terminal. Now, set your multimeter to measure current (sometimes you have to move the red test probe lead to a different jack on the meter) and touch one lead to the unconnected side of the battery and the other lead to unconnected side of the battery connector. You are now measuring the current flowing out of the battery. You may have to change the range setting on the meter, expect a current between 1mA and 10mA.

BE SURE TO MOVE THE RED LEAD BACK TO THE vOLT-OHM JACK ON THE METER OR THE NEXT TIME YOU TRY TO MEASURE VOLTAGE, YOU WILL BLOW A FUSE INSIDE THE METER.

thevargi

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Re: Battery Draining When Amp Turned Off
« Reply #2 on: January 21, 2020, 07:06:34 PM »
Thanks for the response! I really appreciate the help.