Question about power, daisy chains, and supplies - reuse and recycling

[deathfaces]

I just came across an old video camera charger that has a power supply to run the camera without a battery. it's rated 9.8 volts and 1.2 amps.  I was wondering if it would be possible to power multiple pedals from this supply using a daisy chain. From what i've learned, as long as the voltage is correct, pedals/electronics will draw the amount of milliamps they need, for example a typical 9v 200mA power supply on a pedal that draws only 27 mA is leaving a lot of milliamps unused, so by using a power supply that supplies an amp or more  should be able to power multiple pedals as long as they don't overdraw and overheat and kill the supply.

I'm looking for a solution to powering multiple pedals with the things i've got lying around (ie recycling) rather than spending the bread on a dunlop brick that would just be acting similarly (i think). Help me out here.

[theehman]

I don't see why you couldn't use it for a pedal power supply.  It's likely regulated and well-filtered, too.

[earthtonesaudio]

The Dunlop and other power supplies like it have multiple, isolated outputs, which means they have no ground loops and can supply power on either side of ground (positive or negative).  Daisy chained effects must all have the same power requirements as each of the plugs on a daisy chain is wired in parallel with the others.  Daisy chains are more vulnerable to ground loop noise, but many people run daisy chains with no problems whatsoever.

Recycle away!

[boogietube]

I did much the same thing but my Morley Bad Horsie didn't like it one bit. In the end, the Morly got a separate adaptor and that solved the noise issue.

[deathfaces]

That's fantastic! So all my reasoning is right?  I've been using a daisy chain off a Boss TU-2 for years now without any problems, but i seem to keep amassing more pedals...

[PRR]

What they said. Maybe, maybe not.

It would work if ALL your pedals used the same hot/ground polarity. Otherwise you short-out the power supply.

It may not work well because you have power and signal on the same "ground", which leads to ground-loops and general buzz.

As Alex says, it may work great for 2 or 3 well-chosen pedals in an electrically-quiet room. As Sean says, it may be a disaster with another pedal or in a buzzy room.

As Alex also says, isolated supplies are the more universal answer. Someone makes a transformer with like 13(?) separate 9VAC windings, which you can rectify and regulate to separate outputs. This may be neater than a nest of wall-warts.

No, there is no trivial way to break your one big 9V supply into multiple isolated supplies. Oh, it is quite possible, but more work than just using a boxful of simple transformers etc. (The "other way" is a high power switcher, a custom many-winding HF transformer, and a lot of rectifiers and filters.... at least as much work, and more exotic technology than you may be comfortable with.)

10V 1A would be suitable for a TDA2002 chip few-Watt power amplifier driving 8 to 2 ohm load.

[deathfaces]

"As Alex also says, isolated supplies are the more universal answer. Someone makes a transformer with like 13(?) separate 9VAC windings, which you can rectify and regulate to separate outputs. This may be neater than a nest of wall-warts. "

I want to know more about this!

[theehman]

"As Alex also says, isolated supplies are the more universal answer. Someone makes a transformer with like 13(?) separate 9VAC windings, which you can rectify and regulate to separate outputs. This may be neater than a nest of wall-warts. "

I want to know more about this!

Order here: http://www.smallbearelec.com/Detail.bok?no=597

Diagram/specs here:

[G. Hoffman]

"As Alex also says, isolated supplies are the more universal answer. Someone makes a transformer with like 13(?) separate 9VAC windings, which you can rectify and regulate to separate outputs. This may be neater than a nest of wall-warts. "

I want to know more about this!

Order here: http://www.smallbearelec.com/Detail.bok?no=597

Diagram/specs here:

You can also get it from Weber.  You'll also need a rectifier, 2-4 caps, and a linear regulator for each tap you want to use.  R.G. has something up on Geofex (HERE) you should read if you haven't made a power supply before, and I'm pretty sure there is a single "channel"   version on Tonepad.  In fact, even if you have, read R.G.'s article - it explains things quite well, and will help a lot.

If you are going to be playing in a variety of rooms (particularly bars!), you want an isolated power supply - there is nothing like a beer cooler and a couple of neon beer signs to show you the weaknesses in you systems grounding scheme!

[Processaurus]

The video charger is probably regulated, since they included a decimal point in the voltage, and is the perfect voltage for pedals (9 volts plus .7v to overcome a series diode within the pedal used for polarity protection).  It is probably a switching power supply, unless it is large, because of the 1.2 amps.  I've heard often random switching power supplies won't work well with pedals because of switching noise, but a video camara with analog components probably requires clean power, so you might have a great pedal power supply.

At home, on tour, and recording I've used a daisy chain and 1 spot for sometimes >10 pedals, some digital current hogs, for years, the only noise problems with power I recall were with a Boss PS-5 pitch shifter.  That includes an Orange squeezer, which amplifies power supply noise like crazy, it works fine with a regulated supply.

I've never seen a mass produced pedal with a boss type 2.1mm power jack that was positive ground (ie would short out the commonly used daisy chain arrangement),  that's a boutiquer move  .

A note of caution to those designing a pedalboard power supply with that interesting multi-winding transformer, regular (non toroidal) transformers will put out EMI that will go through aluminum boxes and shielded cables, and more, the bigger the transformer.  Lots of you have probably noticed if a cable is laying over a plug strip full of wall warts, it will hum, that's EMI, that needs physical distance of a foot or so or some kind of ferrous metal shield to keep it out of your signal.  I had a bandmate's voodoo labs pedal power apart to fix a while ago and noted it is a toroidal version of the multi winding transformer.  Must be an expensive part, custom made for them...