0 to +18 needed - is +17 ok?

[ethrbunny]

I want to try the Ibanez Flanger from tonepad but it requires +18v. Im trying hard to keep my whole setup running on 9V so Im thinking of trying the MAX1044 "charge pump" from geofex. Unf it appears that it only puts out +17 - how would this impact this circuit?

Flanger:http://tonepad.com/project.asp?id=26
Charge pump:http://geofex.com/circuits/+9_to_33.htm

[Mark Hammer]

The 301 has a 12v regulator on board.  That regulator (and similar ones) need 2vdc MORE going into them than come out of them.  To produce a stable 12vdc output, it will need at least 14vdc coming in.  A pair of 9v batteries in series will do that very nicely for a while.

A 9v battery artificially doubled by a MAX1044 will provide that minimum requisite voltage too, just not for as long because the charge pump requires current and the single battery doesn't have all that many amperes hours in it.

On the other hand, if you powered the MAX1044 with a 9vdc wallwart, the 17v produced by the the MAX1044 would be sufficient to be regulated down to 12vdc needed by the flanger circuit and would clearly not have the rapid death problem associated with using a single 9v battery.

You may wonder why, if the circuit requires "only 12v", which is 6v less than a pair of batteries but only 3v more than a single one, it doesn't use 9v in the first place.  The MN3007 is happier with higher voltages.  The circuit itself likely has a reasonably high current consumption that would turn 9v into 7.5v (or less) quickly.  Though a pair of 9v batteries will drain at a similar rate, as long as each is at least 7vdc, there will be enough juice to supply the regulator and circuit, with a stable supply voltage.  A pair of 9v batteries simply keeps it in "the zone" longer.

[ethrbunny]

Thank you! I will be using a 9V supply from a regulated system. Im glad to hear that I don't need to build a diff one for this project.