Power supply for multiple modules. Will this work?

[Chrometuna]

OK, I hate the way this probably seems like crafty spam. But I've got a serious question on how I can hack or modify these pieces of equip to be 9 or 18 volt power supplies for my various modules, and even other gear that demands an endless stream of 9 volt batteries?

Please see this topic I posted in the for-sale forum. (Yesa I know, and I'm sorry that it might seem like I'm just trying to sell something. But it is much more then that!

http://www.electro-music.com/forum/topic-38221.html

http://www.electro-music.com/forum/topic-38221.html

I've got a big pile of these battery chargers. They re-charge a whole battery of batteries. And I am guessing that they are pretty clean power and well regulated.

They are meant to recharge these weird "8.4 volt" batteries that look EXACTLY like 9 volt batteries. Which I am thinking means this actually puts out about 9 volts. (I'll do a quick voltage check here in a minute)

My immediate idea is that I could tap onto the little pads on the circuit boards that the batteries get their juice from. AND that by cleverly tapping onto a couple of them, I could get 18 volts, AND/OR with two of them get the +/- bi-polar supply that a lot of Ray's designs demand.

Of course there MIGHT be safety features or things in this charger that would prevent that? These things have a LOT of circuitry for "Just a battery charger"!

I need to figure out a "dummy load" I can hook up to this to test my idea and theory before I try it on my precious soundlabs.

And maybe some part of the circuits need to be defeated or by-passed so it fools the charger into NOT seeing a power drain or over-draw as being a bad battery or a battery that is charged and therefore THAT particular charging slot turns off?

OK, I just did my voltage test, and it looks like this thing produces 13 volts. And that is well within a healthy range for most of Ray's soundlab and modular stuff, right?

Any ideas for what else I should test and check for before I put these things 'up on the market' as "Power supplies"?

Heres what it is:

http://www.chrometuna.com/stuff/charger/medicharger%20sm.jpg



And here is one of the circuit boards:

http://www.chrometuna.com/stuff/charger/charger%20pcb%20sm.jpg

[druish]

Yea, how much current can they supply/handle? Plus idk how you can market them cuz they are HUGE

[Inventor]

This is a classic case of DIY circuit abuse. Do not use a battery charger as a power supply. Do not use a knife as a screwdriver - it breaks the knife and doesn't set the screw properly. That's a good analogy for what you are proposing. Actually, if you tried it you might get it to work, but just because something works does not mean it's a smart idea.

Battery chargers do not just put out voltage. They have circuitry that regulates the applied current in different ways for different battery types. Actually I'm not familiar enough with battery chargers to predict exactly what type of calamity will ensue if you try this, but I do know enough to advise you not to try it.

Of course, circuit abuse has it's place such as current starving a 555 chip to get weird sounds. Sometimes people come up with ideas like that which are out-of-the-box thinking and it works out OK. However sometimes they destroy their equipment and endanger themselves in the process. You certainly don't want to get "creative" about a modular power supply - that's just plain dangerous to you *and* your modules.

The typical response when I go off like this is "I tried it and it worked so it's OK". Yeah, and the knife worked the first time without breaking so it must be a good screwdriver. next time you lacerate your hand and go to the emergency room.

Please pardon me if my tone is a bit miffed, it's just that I've been annoyed several times by people making mistakes like this with their hardware, especially power supplies. Power supplies are dangerous. They can shock you, overheat, start a fire, blow up your modules, or do something sneaky like shorten the life of your modules. Do not play with fire, you'll get burned.

Les

p.s. please do continue to think creatively, I don't wish to constrain your imagination.

[Inventor]

Oh, one more thing. You may be able to use the transformer and possibly other components of the power supply in these battery chargers to make your own power supply properly. That's a more reasonable type of scrounging that would be just fine if you do it right. Good luck and have fun.

Les

[Uncle Krunkus]

In this particular case I must concur with my learn-ed friend Les.
Battery chargers are actually designed to deliver a relatively low current (like a 1/10th) compared to a typical load current for the battery in question. If they supplied the kind of current you'd need for your modules they would cook the batteries. That alone is good reason not to use it in the way you described, as it just won't deliver the current you need.
As for wrangling a bi-polar supply out of it? Very unlikely. Even with all the interim circuitry removed, the transformer would be a relatively high current, and yet unipolar type with no centre tap. I'd put money on it.
I agree with Les, that I don't want to seem like a wet blanket, but, believe me Chrometuna, if it currently works as a mass 9V battery charger, leave it that way. It's heaps more valuable and useful for what it was intended.

[Chrometuna]

Good points all.

These things might make good power supplies for other applications, but just not synths?
I wish I knew how to use my osciloscope and other stuff better so I could better gauge what kind of power current etc these things are spitting out.

I now have PILES AND PILES of transformers of all kinds. A lot of them are 12, 15.5 and 27 volt.
I also have massive supplies of little Bournes trim-pots and other pots and switches. Some brand-new never used, and others that I have harvested off of all manner of weird proprietary professionally hand-made gadgets and gear. (The guys/company that made this stuff really knew/know what they are doing)

Anyone need CRT tubes for old oscilloscopes and radars? Circa 1945 and newer? Ive got a bunch, brand new in the box! (New old stock, OEM, never used! Got an old oscilloscope that needs a new Tube? I might have the tube!)

I know I sound like some guy selling stuff out of the trunk of his car, and probably serious bending some rules as far as this forum is concerned.....sorry about that. But Ive got literally TONNES of "stuff" I need to sell, and that some here could probably use.

[Inventor]

Dude, make yourself a grab bag and offer it for sale in the appropriate forum. You'll probably get a buyer. The appropriate forum is:

Wanted, For Sale, Opportunites and Requests
Parts and Components

Les

[Chrometuna]

At 2:30 pm my time (CST, Kansas Time) I'll broadcast a little of me in my garage showing off what some of this stuff looks like.

http://www.chrometuna.com

OR www.justin.tv/chrometuna

or possibly www.ustream.tv/chrometuna

Or here:

Watch live video from Chrometuna's Super Natural Boloney on Justin.tv

[Inventor]

Chrometuna, it's cool to broadcast live but I really wish I could catch a recording. Do you offer recorded broadcasts?

Les

[Chrometuna]

There should be recordings in the archives of that site (The www.justin.tv/chrometuna/old site) I forget what the link says, it might say "archives" or "Previous shows" or something like that.

But I broadcast at random times throughout the day or night, usually late in the night, say around 2 or 3 AM.