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 Powering Paia modules from battery? 
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Joined: Wed Sep 25, 2013 10:31 pm
Posts: 56
Post Powering Paia modules from battery?
Is it possible to power a set of modules from a bunch of 9V batteries (I know I'd need at least four for +- 18V and 9V) or would I have to use one or two for each individual module? What if I use, say an 18V battery pack with a simple inverter circuit for dual polarity and voltage regulators for the +/- 9V, would that work? If so, can anyone suggest a simple-as-possible polarity inverting circuit?


Tue Nov 05, 2013 7:21 pm
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Joined: Sun Nov 09, 2008 2:49 pm
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Post Re: Powering Paia modules from battery?
Battery power for a system of modules really isn't practical unless you piece together a bunch of expensive rechargables.

Then, the connection would be three 9V sources, connected in series, the red from one to the black of the other (or the plus pole of one to the minus pole of the next). The first minus pole would connect as the negative nine volt power supply, the next node up would connect as the zero-volt/circuit-common/"ground", the next node up, positive nine, and at the end, positive eighteen.

We have a 9771-15 kit which is for dual-polarity fifteen volt supplies, but the voltage regulator ICs on it have their output voltage set by resistors on the board. They could be changed to be nine volt supplies, and, another voltage regulator added with the pre-regulator positive supply voltage as its input for the eighteen volt output. This kit simplifies the addition.

http://www.paia.com/proddetail.asp?prod=K60

Or, I just saw these power supplies listed and three of them could be connected like was described above for the batteries.

http://www.allelectronics.com/make-a-st ... PLY/1.html

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Thu Nov 07, 2013 12:35 pm
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Joined: Wed Sep 25, 2013 10:31 pm
Posts: 56
Post Re: Powering Paia modules from battery?
Hmmm.. shouldn't it be possible to use just one 18V power source, if a polarity inverter is used thus generating a positive and negative 18V output, and let's say I use an adjustable voltage regulator on each of the positive and negative nodes to get 9V on each side, thus achieving a positive line with 18V and 9V outputs, and a negative 18V & 9V? No?

Just to give you an idea what I envisioned in my mind, here's a quick and dirty diagram:

Regulator=================== +9V
|
18V source================== +18V
|
Inverter==================== -18V
|
Regulator=================== -9V

This is what I kind of had in mind. Some time ago I saw a simple circuit involving a high frequency 555 IC, which would rapidly flip the polarity and produce a negative voltage that was the same amount as the source. Would this work for what I am trying to accomplish? It seems plausible to me.

PS: I just came across this instructable:
https://www.google.com/url?sa=t&rct=j&q ... 6854,d.cGE

even though I don't get the exact voltages as the source, it pretty much does what I envisioned, I'd either have to look for a 20V battery or hope that everything works with a few Volts below the required amount.


Thu Nov 07, 2013 6:43 pm
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Joined: Sun Nov 09, 2008 2:49 pm
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Post Re: Powering Paia modules from battery?
It is possible to create a negative supply from a positive one and the example you cite is a type of circuit for this purpose, but notice the line in the text mentioning it should be sufficient for one op-amp, in other words, it is limited to about 5 or 10 mA. The negative supply from the 2720 power supply is rated at 100mA.

It gets more complex and requires more expensive parts when you need more current (mA or A) and minimal noise.

There is high-frequency switching of the voltage in polarity inverting and "switching" type power supplies and unless extras are in place to keep this energy out of the mains or on the resulting DC supplies.

If you find a module set that includes a 4771 power supply, it should power plenty of modules.

Its nine volt outputs are regulated to be stable, smooth and free of ripple (potential source of hum).

Its 18V output is not regulated, and, it takes from the power available for the positive 9V supply, so, a simple and beneficial improvement to it would be the addition of another DC power source, say 21V or more (at about 300mA or more), with a simple voltage regulator circuit added to it for the 18V supply to the modules.

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Scott Lee
scott@paia.com


Fri Nov 08, 2013 4:45 pm
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