3x voltage doubler build power question

[LoonDawg]

I am currently building a voltage doubler (actually 3) using this circuit layout http://imageshack.com/a/img839/720/z6c.gif and want to put all 3 in a single enclosure.

I have 3 already built and working but I was wondering if I would be able to power them with 1 9v supply from my Voodoo Labs PP2+. I believe it would have to be powered using one of the 100mA spots (the higher ones are being used). I am going to drive my Fulltone OCD and perhaps Em-Drive at 18v (and I have another just in case I need/want it).

Will the full 100mA be provided (not sure if it's necessary for those pedals) or will it be divided by how many outputs I have running, in this case 3. This also means they are not isolated correct? Is it more like a 1 spot in that regard? or because it is coming through the PP2+ it changes it?

Thanks for your help in answering this noob question. I am still new to the DIY pedals but I am learning more and taking on more projects.

[LoonDawg]

Anyone?

[slacker]

You've got up to100mA in total shared between whatever you connect to it. You should be fine running 2 or 3 overdrives or boosts. The Voltage doublers can only provide a limited amout of current anyway, so you'd probably hit the limit on them before you hit 100mA.
Yeah the outputs won't be isolated.

[ggedamed]

From the datasheet it looks like it needs a supply current that is double the load current (figure 8 ). The voltage doubler has a current capability of around 10mA, so get 20mA for every voltage doubler.
It looks you're fine with a 100mA power supply.

[PRR]

> Will the full 100mA be provided

There's no free lunch. If you double the voltage, you must take half the current.

There's really no at-cost lunch. There's always 1%-200% overhead. For reasonably efficient electronics, pencil 10%-30% loss.

And as ggedamed points out, that chip has a maximum current before it sags really bad.

Three such multipliers on one source are non-isolated.

If you have multiple truly ISO-lated 9V outputs, stack two (custom cable). That gives 18V, full 100mA, with no added loss, though your 18V circuits are not isolated one from the other.

[gjcamann]

I couldn't find it listed in the datasheet, but the web page for the ICL7660S shows a max Current Output of 45mA - which from the datasheet shows a supply current of 90mA. This chip is the beefiest doubler you can get BTW.
http://www.intersil.com/en/products/power-management/isolated-power/charge-pumps/ICL7660S.html

Since devices usually draw half the current when you double the voltage; the actual draw from the PP+ when your running things at 18V should be about the same as at 9V. Since one doubler can nearly max out one PP+ port, I would just use 1 doubler to supply both your pedals.

Good luck!

[LoonDawg]

Excellent. Thank you all for your help

[LoonDawg]

If you are interested in the final product, check this out

http://imageshack.com/a/img835/4929/z63x.jpg

You guys have been super helpful. Thanks again

[slacker]

Nice work, simple and effective.

[PRR]

> devices usually draw half the current when you double the voltage

Mmmmm. Most simple audio electronics pull the same or *double* current when you double the voltage.

Opamps usually pull a semi-steady current from 7V to 36V.

Resistor-loaded transistor circuits ideally bias-up to the same relative voltages (collector near half supply), which is double voltage on resistors, and double current.

Though some bias schemes diverge from these general trends, that usually means the bias will "go wrong" at non-stock voltages, which means the idea of "headroom" is foiled.