# DC Voltage Doubler

Discussion in 'Electronic Basics' started by John, Aug 5, 2004.

1. ### JohnGuest

Hello

What's the best (easiest) way to double a 9V DC supply to 18V DC? The 9V
comes from a 78L09 regulator. The current requirements are very low. Do
any chips exist to do it? I'm an electronics novice so the simpler the
better.

Thanks.

2. ### John PopelishGuest

There are capacitor switches that charge one cap with the supply, then
connect it in series with the supply to double it. These need only a
couple capacitors to double (or make a negative of) a supply. The
base number for one such chip is 7660.

http://www.udl.es/usuaris/p7806757/0000-pdf/conversores cc cc/7660.PDF
http://www.linear.com/pdf/lt1044.pdf
http://ww1.microchip.com/downloads/en/DeviceDoc/21465b.pdf

3. ### Rich GriseGuest

Would it make more sense to supply the doubler with the same raw DC as
the 7909 is getting?

Thanks,
Rich

4. ### John PopelishGuest

The HT7660 is speced for an absolute maximum input of 13 volts, the
lt1044 for 9.5 volts, and the TC7660 for 10.5 volts. So, maybe, but
doubtful.

5. ### CFoley1064Guest

Subject: DC Voltage Doubler
If you need something right away, and the chips mentioned by other posts aren't
available, try a 555-based voltage doubler. If you use a 555, you'll need 2
more resistors, two extra diodes and one extra cap:

http://www.reconnsworld.com/power_voltdoubler.html

Good luck
Chris

6. ### ddwyerGuest

Generate a supply limited square wave, couple to a voltage doubler (3
diodes + 3 capacitors) sitting on top of the + supply . O/P = 9V + 2X9V
- volt drops minimised by using schottky diodes.
Regulate o/p down to 18V.

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