Converting to battery power?

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Roycie Roller
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Converting to battery power?

Post by Roycie Roller » Wed Aug 20, 2008 7:10 am

Hi all,
i'm working on the triwave at the moment & i'm wondering about power. The circuit has a 9v DC input that heads into a LM7809 voltage regulator. I was hoping to just use a 9v battery instead, but there's nowhere on the pcb that allows this (as far as i understand).
Can i sum the +(pos) and -(neg) leads of a battery into the single 9v DC 'input' hole (ie. there's not a +(pos) & a -(neg) hole, just one). I suspect not.
However, i also wonder if one of the holes that are allocated for the pins of the LM7809 could accept a -(neg) wire from a 9v battery instead? The 3 pins are B (input) C (common) and E (output).
And if it's possible, do you ditch the 7809? I've been looking for examples of this being done, but with no luck. Does anyone know how to work this out?
I'd prefer battery power as i like it when batteries are going flat & the sound goes crazy.
Any help would be most appreciated, thanks.

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wetterberg
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Post by wetterberg » Wed Aug 20, 2008 10:37 am

first of all, what happens when batteries are running out is EASILY replicated with any kind of power source - simply put a potentiometer inline with the power, and then you can control the degradation. It's usually called a "Starve" function, something circuitbenders have used since forever.

You can't "sum" the + and - of a battery into one input. that's not how electronics work. IF there's a dc input tab on the pcb that will mean that there's +9v and ground, or "0v" (ftlog, please correct me if I'm wrong)

The DC input *IS* a battery input, if you want it to be. However I suspect the triwave sucks too much juice for regular batteries - you may only get minutes of use from a 9volt?

Why would you ditch the voltage regulator? That would destabilize the whole circuit, most likely... that could be desirable at times of course, but you don't want to fry your triwave either, right?


Anyways, I hope this long rant helps, at least a bit.

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Roycie Roller
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Post by Roycie Roller » Wed Aug 20, 2008 12:47 pm

Thanks! It helps a lot. I think i'll just go with wall power...
I want to put a Noise Swash in the same enclosure, so ideally i want them running off the one supply.
I was hoping to use a battery so i could circuit bend between the two pcb's while they are running. I guess i can still do that, but i'd need to be careful (and not while they're on).
I need to research a bit & learn how to do a jumper between 2 pcb voltage regulators (or if one can regulate two pcb's).
The Swash has a voltage starve mod, so that'd be nice to be affecting the triwave. I have some of the 6- lug pots which could do the trick, i think.

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Cat-A-Tonic
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Post by Cat-A-Tonic » Wed Aug 20, 2008 6:10 pm

If you got a Godlyke or a Onespot it would solve your need for only one power supply.

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Roycie Roller
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Post by Roycie Roller » Wed Aug 20, 2008 11:36 pm

With a bit of research, i found that you can get rid of a regulator & use a battery-

http://img219.echo.cx/img219/6435/noregulator4nk.jpg

This is excellent news coz i really wanted the dying battery effect AND to bend the 2 pcb's so they're cross-modulating.
If one wanted BOTH battery and wall power, that's possible too-

http://img219.echo.cx/img219/638/newdiagram2kr.jpg

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