A custom fly rig style board help!!

[Teddeeh]

Hello chaps and chap-esses.
So. Im thinking about creating a 1 chassis super fly rig type pedal.
Having a delay, an amp style pedal and a booster with a buffer built into it. The detals are not there as which circuits etc but the theory is the same behind it, rather than a pedal board i can take this one mega pedal to any gig and be sorted.
The headache im having which hopefully you guys could help me out with is this,say i found 4 9v pedal circuits i like, have them daisychained into my chassis in the order i want blah blah, rather than individually having 4 power supplys feed each circuit how would i power the board with 1 power supply. Im guessing its not going to be 4x9=36v power supply.

[vigilante397]

When you're running multiple effects from the same power supply you don't add the voltages used, any two points that are connected without anything between them (resistors, etc) will have the same voltage, but you would need to add the current draw to make sure your power supply can handle it.

Example with arbitrary numbers: You have a delay that uses 20mA, an overdrive that uses 10mA, and a boost that uses 5mA. This doesn't mean you need a 27V power supply, it means you need a 9V power supply that can provide at least 35mA.

Analog pedals are generally very conservative for what they require, generally less than 20mA each, but digital pedals vary a bit and tend to be much higher.

Hope this helps

[Jdansti]

Hi Teddeeh. Vigilante beat me to the reply while I was typing. I agree with what he says. Here's my 2 cents:

When connecting multiple pedals having the same voltage requirement to a power supply, they should be connected in parallel. The voltage supply stays the same, in your case 9v. This is the same as using one 9v power supply to daisy chain the power to multiple stompboxes on a pedal board.  The parameter that increases with multiple pedals is current draw, not voltage. So you need to add up the current requirement for the combination of pedals and make sure your 9v supply is capable of putting out more current than the combined current of your pedals.  For example, if the combined current requirement of the four pedals is 600 mA, use a 9v power supply with at least a rating of 800 mA.

All of this assumes that all of the circuits are negative ground. If you have one or more positive ground circuits, you'll need to use separate power supplies for the positive and negative ground circuits.

If you don't know the current requirement of your individual circuits, provide us with the schematics and we should be able to give you an estimate.

[Teddeeh]

Many, many thanks guys.
Once i have it drawn up i will add to a reply. its very interesting to know aswell, i have been building pedals for just over a year now but it still is like a foreign language. Im getting there i think though, but slowly.

[PRR]

> guessing its not going to be 4x9=36v power supply

That is electrically possible, but too-too tricky.

I have four 120V lamps here. Do I look for a 4*120V= 480V outlet? I must have 50 lamps in this house; do I need a 6,000V supply??

No, I feed all of them 120V in parallel.

Series wiring "does make sense" in long runs of street-lights. 100V lamps might be run on a 2,000V source twenty in series. Saves wire. First problem is same-as those 120V holiday light strings made of 12V bulbs: if one lamp blows open, they all go out. Street-lights had a trick: if all 2,000V appeared on one socket, it would punch-through paper insulation, short that one lamp, and the nineteen remaining would split the 2,000V (5% over-voltage). Or the kiloVolt supply would regulate current, so they all ran fine, but more complicated supply.

I recently saw a patent to run two amplifiers, each needing 10V-20V, in series on the existing 50V supply in a telephone exchange. Use the current twice! But considerable added parts and isolation. Made sense for *that* job.

You connect the same as all your lamps and amps on stage. You use a 8-way outlet box, or the equivalent internal wiring. You add the currents to ensure you do not blow-up your power source: five 500W lamps in one 8-way powerstrip is too much for US wall-outlets (2400W max). Most pedal-board supplies aim to please a whole board-full of pedals so you are probably fine without figuring.