Author Topic: Power supply mistake and advice needed  (Read 2483 times)

mills

Power supply mistake and advice needed
« on: November 29, 2009, 07:47:44 PM »
Sorry about starting a few threads today... I know there's a good chance (and good reason that this might be ignored entirely)

So, before I ask the question, I did something stupid.  I know it, and should have read more before planning.  But, my mistake isn't going to go away, so I was hoping for some input as to the best way to deal with it. 

I was making a pedalboard with several effects.  One or two required bipolar or AC power.  I figured out how to run them all off of the same AC voltage, regulate to the +/-DC I needed, and called it a day. 

Being an idiot, I didn't stop to think that daisy chaining AC wasn't going to work.   I have 3 pedals I built or planned to build to take 15-ish VAC, and a frostwave resonator that takes 15VAC

I'd rather not build a spyder, or deal with mains voltage (as I clearly am not prepared for that), and was trying to mount everything on a small pedalboard. 

I figure the best solution is to get a small box to plug one AC adaptor into, and regulate that to 15 or18 VAC.  Then, rather than the usual boss style adaptors, I use stereo 1/8 inch pllugs like old DOD effects, and supply the pedals with +/-DC.  Regulate it in any pedal that might need a different voltage, and I should be set.  I know this isn't as good as isolated power supplies, but its smaller and I think it should be acceptable.  I'd have to modify the frostwave (nothing permanent) , hopefully just by changing the power jack, and putting the + to the positive regulator, and the - to the negative.

So, is there any other better, easier solutions?  Does that sound like a logical way to compensate, even though its not ideal and I should've smartened up before starting the project?  :icon_rolleyes:

Thanks for putting up with my endless questions. 

darron

Re: Power supply mistake and advice needed
« Reply #1 on: November 30, 2009, 12:46:17 AM »
having individually regulated and isolated supplies to every pedal isn't always needed. some purists just like the idea of it. assuming they are supplied something that is well regulated, they all have their own decent filtering and  there's no digital pedals on the line.

you mentioned that you want to regula

I figure the best solution is to get a small box to plug one AC adaptor into, and regulate that to 15 or18 VAC.  Then, rather than the usual boss style adaptors, I use stereo 1/8 inch pllugs like old DOD effects, and supply the pedals with +/-DC.  Regulate it in any pedal that might need a different voltage, and I should be set.  I know this isn't as good as isolated power supplies, but its smaller and I think it should be acceptable.  I'd have to modify the frostwave (nothing permanent) , hopefully just by changing the power jack, and putting the + to the positive regulator, and the - to the negative.

i think it's a great idea to have a bough AC adaptor that then goes into a box and supplies all of the needs of your pedal. it takes care of the mains side that you don't want to deal with and if it's a transformer it gives you an isolation from the mains for safety and your guitar amp for noise. you say that you want to regulate the AC, how do you plan on doing that? most regulation methods on AC change the shape of the wave to something squarer and you should check if that will be a problem for your pedals. regulating the DC to whatever needs it would be cool.

1/8" (or 3.55mm as I know them) jacks bring up issues. lots of companies used them as they can carry the neutral/negative on the outside (which connects to the outsie chassis anyway) and the active/positive on the inside. but when you insert the plug into the jack you're almost guaranteed to short the hot tip to the side of the jack which then shorts the power supply out if you are sharing it with other pedals.

i think that convention these days is to use the "boss style" 2.1mm socket for DC, and people also use the 2.5mm socket for AC, but since it's for you use whatever you really think will be suited, but keep shorts in mind!
Blood, Sweat & Flux. Pedals made with lasers and real wires!

darron

Re: Power supply mistake and advice needed
« Reply #2 on: November 30, 2009, 12:57:28 AM »
who wears short shorts
Blood, Sweat & Flux. Pedals made with lasers and real wires!

mills

Re: Power supply mistake and advice needed
« Reply #3 on: November 30, 2009, 01:14:45 AM »
Hmmmm... shorts.  No one needs to see that.  As soon as I realized my mistake, I knew this wasn't going to be an easy fix.  I made a typo on the regulation thing... my plan was AC in, half wave rectify, filter, and 78xx/79xx.  I think that ought to give me a +,-, and ground to send to effects.  But then I guess I need to keep it at one voltage, or I end up with regulators in parallel which seems to be a bad thing. 

The shorts thing has me stumped though.  At least 1 of the effects on the board are going to be better off with a dual supply, and the frostwave is already made for it.  I should be able to get away with a single supply on a few of the effects though, so those could get a more standard plug.  I'm not really worried about being non-standard, I more or less expected the project to be a self contained board so compatability isn't the first concern.

I guess I could not power up until the jacks are all in place.   :icon_sad:  but thats a pretty sad solution.  

Time for more thinking...  and here I was so excited when the first pedal worked off an AC input.  A powerbar and a bunch of wall warts is looking like the simplest solution unfortunately.

(thanks for taking the time to read and consider!)
« Last Edit: November 30, 2009, 02:09:59 AM by mills »

darron

Re: Power supply mistake and advice needed
« Reply #4 on: November 30, 2009, 05:02:28 AM »
i still reckon the idea of having one power supply 'factory' sounds cool. is running regulators in parallel a bad idea? i do it on my bench supply and don't have issues, but maybe i just haven't been told it's a bad idea and don't know about it. the lazy 'plug it in then turn it on' idea isn't so bad. i never trust OTHER people to do it because as much as i've told them on stuff i've built with a 3.55mm power jack they ALWAYS plug it right in powered and short the thing out lol. your power supply should be ready to handle that sort of thing too.


you sound disheartened. i reckon you have the right idea though (:
Blood, Sweat & Flux. Pedals made with lasers and real wires!

mills

Re: Power supply mistake and advice needed
« Reply #5 on: November 30, 2009, 10:40:08 AM »
I've got to read a bit more about the parallel regulators.  I stumbled across a thread where some people that know what they are talking about mentioned it was a bad idea, but that might have just been to try to get more current out of the system.  I'm not sure yet, but either way, I think I can pull of a +/-15V  supply.

I'm starting to think that it wouldn't be that bad to have an order that things need to ben plugged in.  The effects should generally be staying set up and not unplugged much, so even going out to use it somewhere, the setup is just going to involve putting the board down, and pluggin the AC into the power distribution box.  Shouldn't be shorts that way (until someone decides it looks like fun to play with my pedal board), but I just don't like having something with a flaw like that built in. 

darron

Re: Power supply mistake and advice needed
« Reply #6 on: November 30, 2009, 10:42:53 AM »
it's only a matter of time before there's beer all over your pedals... any help they can get will be good...
Blood, Sweat & Flux. Pedals made with lasers and real wires!