total newbie power supply question and intro...

[mhein68]

Hey all,
   I am totally new to all this. I am 38 and been a drummer on and off since '87 and recently got a guitar cheap (really cheap  ) and and thought about effect pedals and a web search brought me here and other sites.... My first project is going to be a passive a/b switcher like at http://www.fulltone.com/PDfFiles/AB_switcher.pdf. My first ( I'm sure of many) question is.... it states to use a "2.1mm dc jack". Is this for just a Boss/Roland type wall wart or any ol' 9v plug with the right size pole? Is there a cheap source for plugs (yard sale items? I am a yard sale junkie!! ) or just stock up on Boss plugs on Ebay? I have learned alot from searching the post and hope to learn alot int he future!! Any help on this would be great! Thanks!  Mike

[brett]

Hi
You can get 9v *regulated* wall-warts at a variety of electronics shops.
OR, you could get a cheap 12 to 18V unregulated wall-wart and build a power supply.

Charity shops are a cheap source of second-hand wall-warts.  My local shop sells them for $1.
cheers

[mhein68]

I guess I am a real newbie... What does "regulated" mean? Examples to look for at junk shops/charity shop or yard sales, flea markets?

Hi
You can get 9v *regulated* wall-warts at a variety of electronics shops.
OR, you could get a cheap 12 to 18V unregulated wall-wart and build a power supply.

Charity shops are a cheap source of second-hand wall-warts.  My local shop sells them for $1.
cheers

[idlechatterbox]

2nd the Thrift Store suggestion.

What's funny is that I've found the power supply even cheaper if it comes with something. I got an old cordless phone because it had a 9v wall-wart with it. I think I paid 2.50. Phone worked, but I just wanted the 9v. I had to switch the wires so that it was the proper polarity at the plug.

Thankfully, they usually have the volts and mA listed, along with an idiot-proof diagram of polarity/ground.

Good luck

[mhein68]

2nd the Thrift Store suggestion.

What's funny is that I've found the power supply even cheaper if it comes with something. I got an old cordless phone because it had a 9v wall-wart with it. I think I paid 2.50. Phone worked, but I just wanted the 9v. I had to switch the wires so that it was the proper polarity at the plug.

Thankfully, they usually have the volts and mA listed, along with an idiot-proof diagram of polarity/ground.

Good luck

I am I right that most have said a 200ma supply for most single pedals? Also can someone contact me offlist for some clarification on this power supply question?  I am still somewhat confused as what I to look for????Thanks!

[darron]

whoo! poor mhein68, everybody is confusing you!

okay, the power supply doesn't have to be regulated at all since it's only going to be powering an led! cummon people? did you even look at the link that he posted??

here's my ignorant explanation from the way that i see it: the cheapest power supplied take the ac power from your wall and step the voltage down with a transformer. since this is a very crude method it doesn't give out a pure and constant voltage, so it can add a small amount of hum to your effects, especially wahs and fuzzes from my experience. brett suggested a regulated one, which would eliminate this problem because it has a bit of circuitry after the transformer to give out a smoother regulated voltage (yeah?) this will either be a series of diodes or a small stand-alone unit. the regulation unit will drop the voltage a bit though, which is why you need to start with something like 12 volts as brett suggested if you are going to regulate a crappy one for yourself.

BUTTTTT, since you are building a completely PASSIVE box (ie. the audio signal never touches an electrical device  that requires power such as a transistor) and the power will just be lighting a light, it can be anything you want. it's not like you are going to see the lack of regulation in the lighting, and if you did who cares.

get a regulated power supply so that you can run a few effects off of it in the future and have them sound good.

also, put a battery in the box? the dc jack that you'll buy should have 3 pins on it. one will connect to the ground (which connects to the shielding in your leads and to the box to prevent hum, usually negative), one will connect to the battery, and one will give out the positive. when a power supply is hooked up one pin will give out the power from it then switch to the battery's power when it's no longer hooked up. if you probe it with your dmm, or use trial and error, you'll find which ones do what.

now, what power supply plug to use? really, you can use whatever you want. but, if you want to conform and use the boss style plug, you'll have to get any 2.1mm ac socket/chasis with an insulation around it. why? because the outside of the dc socket can't touch the metal box you are using since boss uses positive power on the outside, and the box will probably have to be negatively chaarged. look at all of your boss/ibanez etc. pedals and you'll notice this.

here's my tip for getting a battery in your box: drill the hole just right for the switch so that once it goes in there'll be room to jam it up against the wall. here's a pic i took:



as for the resistors, they can be anything between 1.5k to around 56k. 56k is quite dull, where 1.5k will probably be about the most juice you'll be able to safely give the led before you smell that you fried it.

i said a lot, but hopefully that will answer some questions to things you might think about very soon if you haven't thought about them already.

i'm off on a tour tomorrow morning so i won't be able to respond incase you quote me or ask me a question for a few weeks probably.

best of luck!

[mhein68]

Got a reply back from Fulltone.com where I first found the project....
"We recommend a regulated 9V DC adaptor with negative center pin (2.1mm barrel)."

Thanks to all that helped!  that all for now....Thanks!