Charge Pump for 18v mod to EMG pickups.

[Jamforthelamb]

Hey All,
I want to run my EMG pickups at 18v, and I already have two batteries installed in my guitar, but I don't have enough room for both of them. I figured I could use the "Charge Pump" circuit to double the voltage of one 9v which I know will fit. Is there any foreseeable problems with me doing this ? Any thing specific I need to know before I tackle it ? I already have the 1044 chip, I just need to get the proper caps and diodes for it. Also, I've already added a 25k pushpull (part of my room problem) so that I can go between 9v and 18v, I can still do that with the charge pump right ?

Thanks!
-JFTL

[Ben N]

Why?

You will probably have rather high current drain for onboard--does your guyitar have an easy way to change batteries?

[Jamforthelamb]

It gives more headroom to the preamps in the pickups. Clearer sound, less clipping when playing hard, and it makes them a little less "sterile" sounding. It's supposed to give better definition on the attack as well, but I haven't been playing with it in long enough to detect that.

Yes, it's very easy access, just not enough room for two batteries. I just have them in right now with the cover off.

-jftl

[theundeadelvis]

The charge pump is so simple I would just build it and try. I don't think you're going to damage anything (if others are running this 18v setup safely). The only negative I see possible is noise. I say give it a try.

[Jamforthelamb]

I think I probably will. Just looking for some pointers as I don't know if it's been done before or not.
I know 18v won't hurt the pickups, EMG has a thing on their site saying the will work up to 27v.

[Jamforthelamb]

I was looking at this schematic:
http://diystompboxes.com/pedals/vdbl.html
And I noticed the switching circuit. Is that going to be needed for what I want to do ?
I was planning on building it with this layout:
http://www.aronnelson.com/gallery/main.php/v/TheBigMan-Layouts/voltagedoubler.gif.html

Thanks!
-jftl

[theundeadelvis]

I don't think you'd need the switching, but I'm no expert. You might read this for more info: http://www.geofex.com/circuits/+9_to_-9.htm

[Jamforthelamb]

Hey Everyone,
Just wanted to post that I got the charge pump assembled and installed successfully. Seems to be working great thus far, I just need to try it in a spot with less "noise". I tested it by our TV, so my guitar was picking up interference from that. I also have a 25k push-pull in to go between 9v and 18v.

Thanks for the help!
-jftl

[trendyironicname]

Let us know how the drain goes on that.  I have mine set up with 18 volts right now and it's super crowded in there and I don't really like the cover bulging..  Do you have any problem with the output clipping the input of whatever you put it in?  I like having over 9 for the head room but when I have the knob full on, it's a little too much for some of my preamps.  The line6 will show it clipping the input pretty hard.   Thinking about redesigning my setup to try and get it somewhere in the middle without having the roll off of turning the volume down some.