DC to DC voltage doubler

[tetanus]

Im building a counter that is operated by a small 2.4 volt solar panel that will charge up a 1000mfd capacitor and then discharge when a switch is hit to advance the counter. The counter is 4.5 volts so I need to double my voltage before it goes to the cap. This charging of the cap can take a while if it has to. Ive only found voltage doublers for ac to dc. I would like the circuit to be simple and compact as I intend to make a bunch of these (Im placing them around the house to count various mundane operations such as how many times the fridge is opend in a year; toilet flused, ect.) Can anyone help?

[Chris Smith]

They do make DC to DC convertors. [About fifteen dollars] Pico, Possibly All Electronics, and dozens of other companies sell these convertors. On the Web search for "DC to DC, Invertors, and Power Supplies" for the many companies. If you have to step it up higher than necessary, it is easy to reduce this value for your usage. You can also use a dual pole dual throw switch to charge two caps of half the total value, then when the switch is flipped it stacks the caps output to double the voltage equaling two caps value. Using a relay or two, you can double, triple or what ever voltage you require?<p>[ December 19, 2001: Message edited by: Chris Smith ]</p>

[russlk]

Check out the LM7660, made by National Semiconductor. It is an 8 pin DIP and requires only two external caps to operate. The circuit output is -vin, so if you connect between +vin and -vin it is a voltage doubler.

[toejam]

real good chance you will find a 4-5 v solar cell for 5-6 bucks by shopping the surplus houses

[MrAl]

Hello everyone, nice to see the forum is up and
running again after such a long delay.<p>My idea is similar to Chris's, except you only
use one capacitor and one DPDT switch. When
the switch is, say, 'down', the capacitor
is in parallel with the 2.4 volt battery which
charges it to 2.4 volts. When the switch is
'up' (or pressed in) the capacitor is in series
with the battery, so that it's voltage adds to
the battery voltage. 2.4 volts battery plus
2.4 volts cap charge equals 4.8 volts output.
If it doesnt work, you might have to increase
the value of the capacitor.<p>Let us know what you do and how well it works.