A Few Sound Lab Questions

sohcahtoa · Joined: Aug 12, 2006 Posts: 55 Location: Fargo, ND

So I am about to begin assembly of a Sound Lab within a few days and I am doing a few things extra on top of just building the sound Lab and I want to run these questions by you guys.

Power Questions:

1.I am along with the sound lab also building a midi to CV circuit from PAIA and it runs on 12V. Can I run everything on the sound lab on 12Volts?

2. On top of that if I use a 220 into a transformer for the source? Do I need to look at how many ampres the transformer is putting out?

3. I also plan on including the S&H and some other mods on different boards, can I run these off the same source that the Sound lab is running off of?

4. If I use a transformer there is no "Ground", is that a problem?

Patch Bays:

5. If I use 12V instead of 9 volts does that change the characteristics of the patch bays (inserting 12 V zener diodes instead of 9.1V zeners)?

6. I noticed that the output patch points are in series with 1k resistors, what does this do, and can I apply the same technique to the outputs of the Midi to CV?

Misc:

7. Where is a good place to buy 1/16 aluminum plate?

8. Can is use any type of "Non-Polarized" capacitors in place of "Ceramic" ones?

Note- Feel free to reply to one or more questions, I don't expect one person to know the answers to all of them, but it would be great if they did.

-Sohcahtoa

dnny

Hi sohcahtoa welcome

i will take the power questions and someone can take the others.

sohcahtoa · Joined: Aug 12, 2006 Posts: 55 Location: Fargo, ND

Thanks for the "Power Help" Very Happy

I have a few follow up questions.

Uncle Krunkus · Posted: Sun Aug 13, 2006 4:50 am Post subject:

Whatever the power supply you use, it must have three (3) connections to the SoundLab.
1. 0V is a reference point. It is 9V above
2. -9V and 9V below
3. +9V
0V is also called the ground connection. It is connected to the shield which is around the output connection, it is connected to the safety ground which comes from your mains cable, etc.
I'll include a simple pic of a +/- PSU to make sure that it's clear.

PSU.gif

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Uncle Krunkus · Posted: Sun Aug 13, 2006 5:38 am Post subject:

What country is Fargo ND in?
I assume it's the USA, but you mention 220 source, the US has 110AC mains doesn't it?

Uncle Krunkus · Posted: Sun Aug 13, 2006 5:59 am Post subject:

The 1K resistors on the CV outs are mainly to stop damage to the circuit in case of the patch point being shorted out. The MIDI-CV should already have something similar incorporated into it's design.
The 9V1 zener on the gate in is just to make sure that anything above 9V1 gets shunted to ground (when running on +/-9V).
If you change to +/-12V a 9V1 will still just let 9V1 through to the circuit and shunt the rest to ground. That's fine because I think it only needs 5V to gate the circuit anyway. The problem associated with sending in, say, a 12V gate when it's running on 9V is kind of irrelevant once you change up to +/-12V because there's no "potential" for frying the chips.
Or, in other words. If you leave it at a 9V1 zener that will be fine. If you change it for a 12V zener that will be fine too, (but it will only be guarding against gate voltages which are higher than 12V)
I recently had to get a plate of aluminium, 430*530*2mm, and the biggest hardware store within an hours drive only had .5mm(1/32) thick. A quick check of the yellow pages found an aluminium dealer who cuts any imaginable size, shape, thickness, on the spot for about half the price. I live a fair way from any capital cities, so I'm sure you'll find someone fairly close.
Yes, any non-polarised cap is fine. Most likely an NP electrolytic or 2*1uF MKT in parallel.

sohcahtoa · Joined: Aug 12, 2006 Posts: 55 Location: Fargo, ND

Uncle Krunkus · Posted: Sun Aug 13, 2006 8:41 pm Post subject:

They are hard to find ready made, unless you get one which is made for powering a modular synth, but that would be pricey. You could also try one of those +/-12V "caged" switch mode PSUs, but I get the feeling they be noisy. I'd recommend making your own, because they are a very important thing to have when doing DIY electro-music work.

I've decided to put mine (a precision +/- 15V PSU) into a 1U or 2U rack case with semi permanent connections on the back for my gear, and a switchable 15-12-9V output on the front for testing and experimenting.

When first confronted with the idea of sorting out a dual PSU for DIY work alot of people are put off by what seems like another costly step in building their synth/s but a good quality PSU is worth every cent in the long run.

dnny · Posted: Sun Aug 13, 2006 10:39 pm Post subject: