Road Rage power feed question

[catfud]

I suspect this may be a silly question (sorry!), but can I use the various different power outputs from a Road Rage simultaneously to feed different circuits with differing power supply needs?

For instance, to feed a Ge fuzz the -9v output while simultaneously feeding a headphone amp the +9v output, with everything using the same ground...

[RobA]

The +9, -9, +15, and +18 outputs are referenced to the same 0V (GND on the PCB). So, once you attach the GND on the Road Rage to your signal grounds, those outputs are all happy and work fine even if they are going to different boards. As long as all the boards reference the same GND, it's good. Pretty much the only thing you couldn't do ground wise is attach two different voltage outputs from the Road Rage to ground on different boards.

One thing you do have to pay attention too is the current limit of your charge pump. Most are capable of about 20mA with the LT1054 being able to provide about 100mA.

Other issues can occur if the effects you are plugging together have clocks in them. Sometimes, the clocks can interfere/interact with each other or the clock in the charge pump and cause noise issues. But that's a different issue to the electrical question about the outputs.

[catfud]

Thanks for your reply Rob

The +9, -9, +15, and +18 outputs are referenced to the same 0V (GND on the PCB). So, once you attach the GND on the Road Rage to your signal grounds, those outputs are all happy and work fine even if they are going to different boards. As long as all the boards reference the same GND, it's good. Pretty much the only thing you couldn't do ground wise is attach two different voltage outputs from the Road Rage to ground on different boards.

I may be misunderstanding what you mean, but I don't quite understand why you'd want to connect voltage outputs to ground on different boards?

I was thinking that all the grounds from all boards would be connected to the same DC supply ground.

So if I'm using a +9vDC boss-style adaptor to run this, and that supplies up to c.200mA if I'm guessing that I can still run extra +9v circuits without being affected by the limitations of the charge pump (which, if I'm understanding the schematic right, outputs the -9v/+15v/+18v from the charge pump itself, but it just passes the +9v 'output' through as if it was coming directly from the DC input).

One thing you do have to pay attention too is the current limit of your charge pump. Most are capable of about 20mA with the LT1054 being able to provide about 100mA.

Other issues can occur if the effects you are plugging together have clocks in them. Sometimes, the clocks can interfere/interact with each other or the clock in the charge pump and cause noise issues. But that's a different issue to the electrical question about the outputs.

Thanks for the info - I'm wondering now which guitar effects circuits might have clocks in them... since I'm currently only messing with boosts, fuzzes, and overdrives this is probably something I'm not going to encounter quite yet.

I just added the LT1054 to my shopping list though 

[RobA]

[...]
I may be misunderstanding what you mean, but I don't quite understand why you'd want to connect voltage outputs to ground on different boards?

I was thinking that all the grounds from all boards would be connected to the same DC supply ground.

You wouldn't. It would be a bad idea. You are right that all of the grounds hook together to the same DC supply ground. I was just trying to reinforce that point.

So if I'm using a +9vDC boss-style adaptor to run this, and that supplies up to c.200mA if I'm guessing that I can still run extra +9v circuits without being affected by the limitations of the charge pump (which, if I'm understanding the schematic right, outputs the -9v/+15v/+18v from the charge pump itself, but it just passes the +9v 'output' through as if it was coming directly from the DC input).

Yeah. It looks like that on the PCB too. The +9V is just a straight connection to the input +9V and the output ground and the input ground are both connected directly to the ground plane.

[...]
Thanks for the info - I'm wondering now which guitar effects circuits might have clocks in them... since I'm currently only messing with boosts, fuzzes, and overdrives this is probably something I'm not going to encounter quite yet.

I just added the LT1054 to my shopping list though 

Delays, flangers, and choruses either digital or BBD based are the main things but there are others. Anything with a micro-controller will have a clock too. There are others as well but I'm still not awake enough to think of them now . But most fuzzes, overdrives, distortions, etc. aren't going to have a clock anywhere (unless it has a charge pump and having two charge pumps in the same circuit or nearby circuits is really prone to issues since the clocks are close in frequency and might get coupled elctro-magnetically.)