Power Source question

[dylar]

I built six effects that I am putting in the same box.  I was going to build a 9v power source for them, but I had an idea to take a 9v power adapter for an old answering machine and make a +/- bus using stripboard.  Is there any reason not to do this?  Probably a dumb question, but I haven't done anything with power sources before. Thanks!

[Cardboard Tube Samurai]

Depends how many amps or milliamps you require to run all of your effects VS the output of the supply. For instance, if it's a 250mA supply but you'd be pulling 400mA with all your effects turned on, it's not going to happen.

[twabelljr]

It should work if the amp rating is high enough. A Boss power supply for powering multiple effects (the one I have) is 9V dc, 1A, 9W. Check the output ratings on the answering machine plug. If it is only 150Ma I doubt it will work very well.
Edit: Also, what Cardboard Tube Samurai said..

[jasperoosthoek]

Connecting all the ground wires to one 'central' point is considered good practice. It's called a star ground and can avoid cross talk between high gain effects. Then do the same with 9V wires going to each effect. Your strip board would work fine and IMO is a very good idea .

Don't run additional ground wires from each effect to the other (like in normal separate stompboxes where the patch cable has a signal and ground/shield). Only single strand signal wires to the switches are needed if they are in a single box.

Good luck!

[smallbearelec]

First, measure the power required for each effect. You can find this out by connecting a multimeter (set to measure milliamps) in series with the positive battery lead. Add up the figures, and compare with the current rating of your adapter. Presuming that it can supply enough juice, you still have to deal with the fact that most non-effect-specific wall adapters have little filtering and no regulation. You Can add those to a wall adapter, and it's a legitimate way to go. Search previous threads here on power supply topics for ideas. Or build a Small Wart (or two):

http://www.smallbearelec.com/Projects/SmWart/SmWart.htm
http://www.smallbearelec.com/Projects/SmWart2/SmallWart2.htm

Regards
SD

[markeebee]

Definitely worth including a regulator and filter caps as shown in the Smallwart.

Many wallwarts are very poor, like Steve says, and some pedals can be fussy.

[jasperoosthoek]

A friend asked me to fix his dirt box. It turned out his dad had soldered a 9V wall wart to the box. The nine volts was not properly regulated and was higher (maybe eleven volts).

In theory this shouldn't have destroyed the thing but it did. When it still worked it was very noisy as he recalled. So get a proper one .

[dylar]

Thanks for the feedback.  Given the potential noise problems I think I'm going to build one myself.  Maybe I'll try the adapter idea at some point to see what happens.

[newfish]

'Beavis Audio' has an excellent Hum Eliminator project.

I'd recommend this, (or something similar) to be built into your supply.

The mains in your rehearsal room / home may be 'clean', but you can't guarantee the same noise-free supply wherever your next gig is...

It's only a handful of components too!