+/- 17V (or 25 or 34, etc.) from one 9V battery, Success!

[Ripthorn]

Hey guys, in my quest for a simple higher voltage bipolar power supply, I got looking at the MAX1044 (TC1044 and similar) and noticed it can do the voltage multiplication and the negative voltage conversion with a single chip.  So I wondered if I could multiply the negative voltage.  I breadboarded the thing and it works.  I got +/- 17V from a 9V supply.  My total circuit is an LM7809 in front of the +9V of the attached schematic and it works great.  I just thought maybe others could use this for whatever they need as well.  Enjoy.

[anchovie]

Thanks for that! What are the values of the capacitors?

[andrew_k]

I was looking for something like this couple days ago. Thanks!

[nosamiam]

Thanks! I'm sure at some point I'll use this. Would work great for modifying modular synth circuits to work as stompboxes, maybe better than using a voltage divider/bias setup.

[LMJS]

Go to http://www.geofex.com/
click on the Circuit Sweepings on the left hand menu.
The first two articles have something you will like to see.

[Ripthorn]

Go to http://www.geofex.com/
click on the Circuit Sweepings on the left hand menu.
The first two articles have something you will like to see.

Yeah, I have read both of those numerous times and between those and the MAX1044 data sheet, I figured it should be possible to both, not just one or the other (which was the impression I always got by those two articles by RG).

The caps are 10 uF and the diodes are 1n4001.  If you go to higher voltages, make sure the diodes and caps are up to spec.

[frequencycentral]

That's very cool work Brian! Well done!

[Dimitree]

thanks
did you try it with a common circuit to see if there are voltage drops?

[rotylee]

And what is the useful life span of a 9v battery running at these voltages?

[Auke Haarsma]

that is a very nice find!

[Ice-9]

Excellent find Brian , i'm sure this will see its way into one or two of the circuits i'm working on at the minute.

[aron]

There's something about ground that comes to mind. I forgot, but these chips can be prone to cause whining in the power supply if not done right. It's been a while since I used them.

[frequencycentral]

There's something about ground that comes to mind. I forgot, but these chips can be prone to cause whining in the power supply if not done right. It's been a while since I used them.

Pins 1 and 8 are connected, so the oscillator is running with it's speed boosted beyond human hearing, plays merry hell with bats and dolphins though. The one to avoid is ICL7660 which is the same as the MAX/TC but with no oscillator frequency boost feature.

[Ripthorn]

With a common circuit connected, I was getting about 15V, but I think that might be more because I am pushing my bridge rectifier (prior to the regulator) at pretty close to its current limit.  There is no whining and it works quite well from the 15 minutes I had it running under normal conditions last night.  Due to the voltage drop, if that is a normal thing, I might feed it 12V and see if I can get about +/-20V going on.  As for lifespan on a 9V, that depends on your current draw, but the 1044 is a very efficient chip, so it seems like you would get roughly 1/4 of the lifespan (since the voltage is 4 times greater).

[doitle]

You can do this with a Linear Tech LT1026 too. Circuit as follows:



Results as follows:


Looks a little simpler but the chip might cost a bit more. They seemed to be about 3$. Not sure how much the max chip is.

[cpm]

12v will fry your MAX, it only stand up to 10v, which is already at the dangerous border when using an unregulated 9v supply

for this reason i prefer either ICL7660 or LT1054

[frequencycentral]

12v will fry your MAX

Well. that's what the data sheet says, but I know different.

[Ripthorn]

My chips are actually TC1044's which have a 13V max.  The LT chip circuit looks cool, but the TC1044 is $1.02 at Digikey.  I just said MAX1044's because they are better known by that name (the TC1044  is a pin for pin replacement).

[LMJS]

Here some more of the same:

http://analogguru.an.ohost.de/001/schematics/Analogguru_SymmVoltMultiplier.gif

http://www.aaroncake.net/circuits/vinvertr.asp

http://img213.imageshack.us/img213/1772/avgmka1.gif

http://img166.imageshack.us/img166/6271/anderton9vdualsupplycg1.gif

[earthtonesaudio]

As you increase the number of stages, the ripple goes up, the efficiency goes down, and the component choices become critical.  These types of voltage multiplier circuits work best with either very light loads, or very powerful oscillators.  Not to discourage their use, just be aware that it's a specific tool for a specific application.