building a mixer power supply.. is this realistic?

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kiira

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Aug 2, 2004
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536
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Baltimore - Blobsville USA
There ia a line mixer I really want on ebay which would solve a lot of problems for me right now since I am still repairing my Tascam M512 and don't know if it will even be useable in the end. :sad:

It's this one, a Tascam mm-1 but it has no power supply

http://www.2tough.com/~kiira/rec/mm1-leftA.jpg

It will probably sell cheap, maybe really, like I can afford and it seems to me that building a bipolar +/- 10V. 12 watt ps shouldn't be all that hard. The connector plug socket looks unfamiliar but even if I couldn't find one I could wire something up it seems like, like directly to the board.

What do you guys think? I might even be able to get a schematic from Tascam but even if I couldn't ....

I really like all the flexibility and total coolness of my M512 but it's destined to be converted into a coffee table if I can't fix it and that is looking bleak. I'd really rather be trying to track some songs I've written and learning more about recording. This line mixer has 20 ins/ 20 direct outs, 4 auxs, and two stereo masters. I don't need more right now, I don't use more than 16 tracks per song and if I did I would do some summing in the computer first. acourse these usually sell for $150-$200 so I'd have to decide if I want to wait a bit and buy one with working PS. It will only take me four or five years to save $200. :razz:

Oh and I have 5 pres now with 3 on the way, so no preamps needed.

opinions wanted yo,

Kiira



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Larrchild

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Jul 15, 2005
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Fort Lauderdale, Florida
Regulated + - 10v should be easy to get for low bucks.

A Radio Shack 12 0 12 volt transformer driving a bridge rectifier. (with caps)

Then a 7808/7908 pair of 3-terminal regulators or even better, 7809/7909 regs.

Use those to drive the bases of a pair of pass transistors (NPN/PNP), and since you have a .6volt drop across the transistor, you would get (with 7809).. 9.6vdc reg'd out of the transistor's emitter. Heatsink the devices for coolness.

Noww..instead of grounding the 3-terminal regulators, start adding 1N4004 diodes in series to ground. Each one acts like a .6volt zener and will bring the regulation up .6vdc per diode. Dial 'er in.

Or..some cheap PowerOne or Lambda supplies on the surplus market.
They all have trims in 'em. But a 24 volt one won't like 10v!

Either way, It's >$20. =)

PS, a schematic could easily be drawn, now that i can, lol.
 

kiira

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Aug 2, 2004
Messages
536
Location
Baltimore - Blobsville USA
[quote author="Larrchild"]Regulated + - 10v should be easy to get for low bucks.

A Radio Shack 12 0 12 volt transformer driving a bridge rectifier. (with caps)

Then a 7808/7908 pair of 3-terminal regulators or even better, 7809/7909 regs.

Use those to drive the bases of a pair of pass transistors (NPN/PNP), and since you have a .6volt drop across the transistor, you would get (with 7809).. 9.6vdc reg'd out of the transistor's emitter. Heatsink the devices for coolness.

Noww..instead of grounding the 3-terminal regulators, start adding 1N4004 diodes in series to ground. Each one acts like a .6volt zener and will bring the regulation up .6vdc per diode. Dial 'er in.

Or..some cheap PowerOne or Lambda supplies on the surplus market.
They all have trims in 'em. But a 24 volt one won't like 10v!

Either way, It's >$20. =)[/quote]

Coolness. Yeah, the power supply shouldn't be that hard, I've built at least 10 or so no big deal. Oh and it is also 19 watts so it should be about 1A per rail. oh wait lemme go model that with LTSpice. I'm going to writing articles for audi0Xpress in no time :cool: :razz:

I like the powerone or lambda idea better though... it's faster. The hamfest is exactly one month away and I see Lambda supplies often at them.

PS, a schematic could easily be drawn, now that i can, lol.

Did you try LTspice then? The schematic drawing part is really nice and no restrictions like Orcad.

thanks very much for the feedback. :grin:

Kiira

editted for spallling
 

Larrchild

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Joined
Jul 15, 2005
Messages
801
Location
Fort Lauderdale, Florida
Those common household Radio Shack 12volt supplies often had voltage adj on them also. a pair of those, even if mismatched in appearance.

And indeed I am using the wonderfully-free LTSpice, and soon will be creating models to represent my real world results.

Thats how you do it, right?'
 

henk

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Joined
Nov 23, 2004
Messages
209
Location
Chiang Mai
Do you have the schematics of that mixer?
Then look if you can put powersupply up to +/- 15..18V , this will make the sound much better for better headroom , most opamps can do that , so look good to the schematics if that is possible.
 

Fentonio

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Joined
Sep 5, 2012
Messages
1
Hi all,

apologies for dragging this out of the mists of time, but I have run into the same problem of having an MM1 with no power supply.

From this post it seems all is not lost, so I have a few questions -

First, would a relative beginner stand a chance of building an adapter like this from scratch? I have a practical mind, a soldering iron, and an interest in getting better at using it...

Or alternatively would it be possible to buy an appropriate adapter and hardwire it in/build a socket? If so, did you guys find out the pin layout and other neccesary info?

Really hoping there's a way around this, there is a company that sells these adapters for £100 (!!) or I could pay a professional to do it for probably even more, but if I can do it myself that would be great!
 

pstamler

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Jan 24, 2005
Messages
1,509
Location
St. Louis, MO, USA
Or, if it's gotta be +/- 10V, LM317/337 regulators work well, better performance in fact than fixed 3-terminal regulators.

Peace,
Paul
 

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