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 powering new 9700 modules with regulated 12v DC 
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Joined: Sat Jul 30, 2011 5:46 am
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Post powering new 9700 modules with regulated 12v DC
I noticed in the schematics that these modules are powered by 12v DC. I'd like to confirm that I can power these with a regulated 12v DC supply. I am going to be running the paia modular system off a solar battery bank running at 12v DC. I'll be using the Tip Top audio powered "Seuss" board for regulated 12v DC power to the 9700 modules. Would this be possible?

I'm sure I'm going to have to figure out how to make custom Doepfer/Analogue Ssystems to Paia power adapters as well.

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James


Mon Aug 01, 2011 5:51 pm
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Post Re: powering new 9700 modules with regulated 12v DC
anyone?

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James


Thu Aug 04, 2011 8:49 am
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Post Re: powering new 9700 modules with regulated 12v DC
Hello James.

I think you might be thinking you just need two wires carrying a 12v dc supply for powering the 9700 series modules, but it would be three--for dual dc supplies, one positive and the other negative with respect to a zero volt ground/circuit-common.

You could get this by stacking two of the solar-battery packs and using the mid-point of this series connected power source as the ground.

I can imagine two solar-battery packs might be fairly bulky and expensive, so it might be worth a try, using one pack and a 12vdc to 120vac converter and plugging into this portable line voltage with the wall-mounted transformer or switching-supply for the Zeus board.

Thanks.

--Scott

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Scott Lee
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Fri Aug 05, 2011 10:45 am
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Post Re: powering new 9700 modules with regulated 12v DC
PAiA-Scott wrote:
Hello James.

I think you might be thinking you just need two wires carrying a 12v dc supply for powering the 9700 series modules, but it would be three--for dual dc supplies, one positive and the other negative with respect to a zero volt ground/circuit-common.

You could get this by stacking two of the solar-battery packs and using the mid-point of this series connected power source as the ground.

I can imagine two solar-battery packs might be fairly bulky and expensive, so it might be worth a try, using one pack and a 12vdc to 120vac converter and plugging into this portable line voltage with the wall-mounted transformer or switching-supply for the Zeus board.

Thanks.

--Scott

Thanks for the reply...so in a nutshell, as long as I can get 12vdc pos, neg & ground (via 2 cells) to the new 9700 modules I'm good to go, as long as I've got enough amp hours in the batts to work with.

the current draws you have listed for the new modules, what voltage is this draw based on?

thanks again for the reply.

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James


Fri Aug 05, 2011 10:52 am
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Post Re: powering new 9700 modules with regulated 12v DC
12v, but this is based on an AC supply. Perhaps it is half of the VA rating - so the transformer gives 1000mA for 12V AC and from this you get 12VA (1A * 12V)- so 6VA for positive and negative each. That's rather simplistic, and of course the MIDICV unit also has a +5V derived from the +12V supply so perhaps the +V current draw is greater than the -V.

For my 9700s - and given that I live in the UK and could not use the 120VAC transformer supplied with the 9700s, I first used a dual 12V transformer with 24VA, and took the power from one of the two secondary windings. This works fine, and I cannot seem to find a single-secondary 12V transformer with 12VA (so 1000mA). Transformers are rated in Volt-Amps (VA) and if you want 1A from a dual-wound transformer then you need the VA to be twice the voltage times the amperes.

With DC current from a solar cell pack or battery, you need 1 amp and 12 volts, but of course these devices vary in their electric pressure (voltage) and quantity (amperes) during the day (solar) or depending on their charge (batteries). You only need 500mA from each (+ and -) 12v rail, connected across a 24v potential (with 1/2 the solar cells or batteries on one end of the 0V (ground) and half on the other). Remember that voltage is a relative pressure, so many devices that are rated to work on +/-12V and 0V will also work with +24v, 0V and 12V (ground - but only relative to the other voltages). Thias is how I understand it - it's like the U-bend of a toilet - the currents always try to achive BALANCE.

But... you will never damage the synth by under-powering it, so plug it in and see. Remember that current is drawn, not pushed.

Best,
Ed


Sun Aug 07, 2011 4:53 pm
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Post Re: powering new 9700 modules with regulated 12v DC
thanks for the info synchroma. I intend only to power the newer modules via the battery bank, for now. At least until I figure out how to make an adapter to go from the Tip Top Audio ZEUSS powered board, to the Paia modules.

The 1amp power rating you give is very helpful, as this sets-up how I'll size the battery bank for powering the modules. The plan is to use (2) 12vdc batteries that are about 32amp/hr rated (20hr rating). I'll use the + from one battery, the - from the other, and the combined +/- from both to create the power supply. For now, I'll put in a simple switch off the batter bank, before the synth, and make a power distribution block for the modules with terminal strips, sort of like how Scott has shown as a way to power the new 9700 modules off of the midi/cv module kit. Course I'll put an fuse/breaker between the batteries and the synth as well.

I'll keep ya posted on how it goes....Ohh..and thanks for the "underpowering" tip. Good info to know, that I could power it with 9vdc as an experiment and see what kind of strangeness comes out..:)

Another question:

the SG (signal ground) do I need to hook this up to anything? or be aware of anything with this? I see it in the schematics, but am a little unclear as to what it does.

thanks again for the info synchorma

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James


Mon Aug 08, 2011 6:08 am
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Post Re: powering new 9700 modules with regulated 12v DC
Hello James.

G and SG go back to a single point on the dc power supply, ie the junction of your two series-connected 12v supplies. Use one wire for each so the power supply filter capacitor, LED switching, etc, currents on G are most isolated from the audio currents on SG.

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Scott Lee
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Mon Aug 08, 2011 1:00 pm
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Post Re: powering new 9700 modules with regulated 12v DC
perfect! thank you for the tip of separating the ground from signal ground. I'll create (2) ground leads from my parallel batteries. This is going to be a cool solar powered synth.

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James


Mon Aug 08, 2011 1:05 pm
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Post Re: powering new 9700 modules with regulated 12v DC
I think you have it right, connecting the plus pole of one supply to the minus pole of the other supply and using this node as the 0v/circuit-common/ground, but this is a Series connection for the batteries. Parallel connection is when they have the plus pole to the plus pole and the minus pole to the minus pole.

Here's an example for using two nine-volt batteries with red/black lead snaps for dual-polarity, nine volt supplies. The principle is the same, you stack, or series connect the two batteries and use their mid-point as ground. The red from one snap goes to the black of the other snap and this is 0vdc/circuit-common/ground. The free red wire is the positive and the free black wire is the negative:

Attachment:
+and- 9vdc.pdf [22.62 KiB]
Downloaded 1419 times

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Scott Lee
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Mon Aug 08, 2011 2:07 pm
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Post Re: powering new 9700 modules with regulated 12v DC
got it...for the 2nd 0v SG grnd..I just tap a second line off the combined +/- ground lead then?

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James


Mon Aug 08, 2011 2:21 pm
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