Voltage Doubler

[wmmullaney]

Hi, I wanted to know if this circuit will work. Also, what should the capacitor values be?

 

[Nigel Goodwin]

At a quick glance it looks OK, but you don't give any information to suggest and values?.

 

[wmmullaney]

Ok, maybe 1.5v in and 3v out.

 

[Nigel Goodwin]

Ok, maybe 1.5v in and 3v out.

You're still telling us nothing - we need to know frequency and required current - but at those voltages it wouldn't work, too much loss through the diodes.

 

[blueroomelectronics]

It's also an AC design, a 1.5V battery won't work.

 

[wmmullaney]

Ok, know of any Dc disigns?
(powered with a 1.5v battery)

 

[Diver300]

It is impossible to increase a voltage with a DC design.

You can use AC with capacitive doublers, boost regulators or transformers.

If you Google "Joule Thief" you will come up with a very simple voltage increasing device.

 

[audioguru]

The Joule Thief circuit has about only 5mA of output current. There are many other voltage boosting circuits with a higher output current.
You forgot to tell us how much current you need. 10uA? 1mA? 1A? 10A? 100A?

 

[blueroomelectronics]

Use two 1.5V batteries.
Whenever you convert from one voltage to another you introduce losses.

 

[freeskier89]

To double the voltage you could put the AC leads in your schematic up to the output of an h-bridge which is being driven with a 555. That or you could make a crude inductive boost converter with a 555.

But in either of those cases you are introducing an IC, and you might as well use an uber easy to use voltage doubler IC from Maxim/Dallas Semiconductor. But a lot depends on your current requirements.

 

[audioguru]

use an uber easy to use voltage doubler IC from Maxim/Dallas Semiconductor. But a lot depends on your current requirements.

The Maxim ICL7660 can supply about only 10ma as a voltage doubler. A 5V supply becomes only 8V. It ain't much current and the voltage isn't doubled.

 

[things]

If you tell us how much current you need, or what your driving with it, will will be able to help you more!!

 

[freeskier89]

The Maxim ICL7660 can supply about only 10ma as a voltage doubler. A 5V supply becomes only 8V. It ain't much current and the voltage isn't doubled.

Ah true. This should work though... for most applications (obviously depending on his current requirements) **broken link removed**

 

[audioguru]

The MAX856 to MAX859 have a minimum typical input voltage of 0.8V but some need 1.8V.

 

[wmmullaney]

I'll try the Joule thief, thanks anyway!

 

[HarveyH42]

Just ran across this today. Not sure if it works, guessing it's more of a battery-killer. Fewer stages should give lower voltages. Not sure how much current you can expect.

*Should have mentioned, guessing the chip is a 74HC240.

 

[audioguru]

The 74HC240 is a buss driver with "high current" outouts when it has a 5V supply. With a 3V supply its output current is less.
I couldn't find spec's about its output current.

I think its output current as a multi-stage charge-pump is very low with poor voltage regulation.

 

[wmmullaney]

Ok, i guess the joule thief is the easiest, will it work with higher voltages?

 

[audioguru]

The Joule Thief circuit can light a 3.5V white LED dimly if the battery voltage is 0.8V. It might even light two white LEDs in series (7V).

The output is pulses, not DC. An extra few parts would be needed to smooth the pulses into DC.

 

[Hero999]

You haven't sait what you want to power.

A Joul Thief requires a voltage regulating load like an LED or a zener diode or else the output voltage will be very high and could destroy the circuit connected to it.