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overshadow
Joined: Nov 07, 2009 Posts: 2 Location: portland, oregon, usa
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Posted: Thu May 24, 2012 11:32 am Post subject:
converting single dc to dual voltage(?) |
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Hello All!!! I may be posting this in the wrong section, and if so, I appologize.
I generally work with single voltage circuits running on 12v or less but I'm building myself a synth/workstation that currently runs on a single +12v dc and I'm now looking to introduce an adsr running on +-12v.
I'm really not trying to redo the entire power system for the entire piece for this one circuit.
I'm searching for a simple solution...so...
My question is; Is it possible to run the main +12v power into two independant 12v voltage regulators (thereby resulting in two independant 12v), sending one to the +12v and one to the -12v of the adsr circuit?
Or is -v actually inherently different (flipped)?
If that's the case, does anyone know of a simple solution to this problem?
many thanks |
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Mongo1
Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC
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Posted: Thu May 24, 2012 1:47 pm Post subject:
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You can't use two regulators as you suggest. That is strongly related to perpetual motion.
There are some chips out there that can do the conversion for you. Depending on your needs though, I'd really suggest converting over to a dual supply system. Doing that would really open up the number of circuits you could use.
Gary |
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overshadow
Joined: Nov 07, 2009 Posts: 2 Location: portland, oregon, usa
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Posted: Thu May 24, 2012 5:51 pm Post subject:
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Hey Mongo,
thanks for the reply.
looks like I'll need to upgrade to a dual supply.
Out of curiosity though, would it be possible to run a +-12v circuit off two independant power supplies (one for the -12v and one for the +12v)? |
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Mongo1
Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC
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Posted: Thu May 24, 2012 6:58 pm Post subject:
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Quote: | would it be possible to run a +-12v circuit off two independant power supplies (one for the -12v and one for the +12v)? |
Yes - that's pretty easy. You would connect the positive side of one supply to the negative side of the other. That would be your system ground.
Gary |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu May 24, 2012 7:02 pm Post subject:
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Be wary that you'll want the two to switch on/off at the same time. I recall something about it being a bad idea to have two wall warts hooked up such that one was on and the other off, for example. |
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richardc64
Joined: Jun 01, 2006 Posts: 679 Location: NYC
Audio files: 26
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Posted: Fri May 25, 2012 6:32 am Post subject:
Re: converting single dc to dual voltage(?) |
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overshadow wrote: | If that's the case, does anyone know of a simple solution to this problem? |
I love how that one word always seems to fall by the wayside in these threads. It's like it causes a blind spot.
Although a dual supply would allow more types of circuits to be used, if you really don't want to "... redo the entire power system for.. this one circuit" it might be possible to adapt that particular ADSR to single supply, since envelope generators in general take in a unipolar signal (the gate and/or trigger,) and put out a single-ended voltage -- the envelope.
Let's see it. _________________ Revenge is a dish best served with a fork... to the eye |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Posted: Fri May 25, 2012 7:45 am Post subject:
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You can buy (although they are quite expensive) DC to DC converters. These days they come on one big black chip, say,.. matchbox sized. You put one DC voltage in, and get another out. Up, Down, and I'm sure Scott Stites told me about one which took in say 12DC unipolar, and converted it to +/-15V with a centre ground.
Keep in mind that they can't supply anymore wattage than what you put in, in effect, even less with efficiency. So If you had 12VDC unipolar in @1A, you wouldn't get +/-15V at anymore than 300-400mA.
Apart from that, I'd say, just bite the bullet and invest in a good quality linear PSU +/-15VDC @1A
It will pay for itself in frustration very quickly if you plan to do much more Synth DIY. _________________ What makes a space ours, is what we put there, and what we do there. |
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analog_backlash
Joined: Sep 04, 2012 Posts: 393 Location: Aldershot, UK
Audio files: 21
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Posted: Thu Nov 01, 2012 5:40 pm Post subject:
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Hi,
I've not tried it myself, but I've seen circuits in the past where a very simple DC-DC converter is made from an oscillator (often CMOS) and a couple of capacitors and diodes. This generates a negative voltage which can be used to supply the the -V pins of op-amps. There is an example shown here:
http://www.extremecircuits.net/2010/06/negative-auxiliary-voltage.html
The current supplied is small, but if it's just to power a few low-current op-amps, it might just work. It's worth a go as nothing much is likely to go wrong.
However, it's still a better option in the long run to build a dual-rail supply. The one I'm using now was built by my cousin for me when I first started getting into electronics. It must be 30 years+ old now!
Just a thought,
Gary |
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