utility: use 2 x 9v batteries, old ones, and get fix 9v out, fix (regulated)

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utility: use 2 x 9v batteries, old ones, and get fix 9v out, fix (regulated)

j-pee
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hi,

I've just come upon this idea by Dave Frost, here:
https://www.thegearpage.net/board/index.php?threads/building-a-battery-powered-pedalboard.1131722/#post-14021222

and I really like it...

the point: when you have 2 x drained 9v batteries, you don't have to throw them out...
you can use them, for long, and they will provide a fix 9v power source...

I haven't tried it yet... haven't built it, haven't tried it...
the schematic came from the TS78L09's datasheet...
I wonder if this is a good idea...?

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EDIT: NO, it is not ↑
it doesn't make sense to use this with drained batteries...

however, using it with two fresh ones, we can get a stable and fix 9v, which might make sense...
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Re: utility: use 2 x 9v batteries, old ones, and get fix 9v out, fix (regulated)

j-pee

to answer my own question: not a good idea...


........
why? cause for a regulated 9v power source one needs NOT 11.5v as I wrongly stated (I had read the first IC's data, not the 9v IC's) but 15v

15 v is the minimum...
and 7.5 volts for a 9v battery is almost okay...
I mean, a drained battery I'd define from around 7.5 v...

and two of these would be just nearly okay, perhaps only for some minutes...

okay, let's see 3 drained but usable batteries...
below 7.5 volts...
but how low can we go?

in this article an engineer, Russell McMahon explains that a 9v battery at 6v is dead...
and that it is called "dead for a reason" :)
https://electronics.stackexchange.com/questions/475279/is-it-possible-to-use-a-dead-9v-battery-as-a-5v-power-supply


So, the usage could be like connecting 3 drained down batteries...
still above 6v but below 7.5 volts...

NOT a very great usability range...

not to mention that most pedals use nice PSUs... not batteries... except for fuzzes....

I only leave this post here to save time for some others in the future...

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keywords: dual power supply dual battery power supply voltage regulated power supply, voltage reulator