200V from a 3V battery? 5

[tuned99]

I have been asked to investigate the possibility of generating a large voltage from a 3V battery. The specifications are vague at the moment but for now the range may be anywhere from 50 to 200V (single or dual supply). This is for a portable piezo driving application. Aside from charge pumps and DC/DC converters, I am somewhat at a loss on how this might be accomplished. Any leads to follow would be much appreciated!

 

[VEBill]

Examine those cheap disposable cameras that have the built-in zenon flash. The ones that I've taken apart used two AA batteries (3 volts!) and the voltage across the flash tube is in the area of several hundred volts DC. I believe that they use a one-transistor oscillator and a simple step-up transformer-rectifier circuit. The shutter trips the flash trigger coil. Obviously be careful or you'll be zapped.

Another technology is piezo 'transformers' where a small voltage makes the crystal vibrate, and the vibrating crystal is used to make a higher voltage on another set of terminals.

 

[nbucska]

It is possible but it is neither cheap nor efficient.
Due to the high current, the losses will be high.

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[IRstuff]

Some hand-held night-vision sights run off 2-AA cells and the intensifier within requires several hundred volts to operate.

TTFN

 

[felixc]

Complicated or not will depend on how many milliamps or microamps that you will need.

 

[sdmays]

I think VE1BLL is on the right track. With careful component selection and inverter design, the 50V to 200V can be generated fairly efficiently with one or two transistors. Ripple may be a concern...

Zetex transistors have some App Notes for simple and efficient inverter designs using ZTX8__ transistors.

I just 'googled' "zetex emergency inverter" and found a circuit in which you may be interested.

 

[IRstuff]

If you can boost it to 5V:

http://www.picoelectronics.com/dcdclow/pe64.htm

TTFN

 

[stevenal]

http://www.national.com/appinfo/webench/power/SS/SS.cgi?flow=power&step=0A

 

[tuned99]

Thanks for the input! I'll start with the camera dissection and proceed from there.