Battery life extender.

C. Stanforth in the December 2001 issue of Electronics World (p957), provides a novel pulsing-type battery life extender. Although invented for torches and bike lamps, it seems possible that other applications could be found in amateur radio. A CMOS-type 555 timer IC (7555) acts as an astable driving a transistor switch, permitting a 2.5V bulb or other load to be powered from a 3.5V battery, yet providing virtually constant illumination as the battery voltage falls to about 1.8V. As the battery voltage falls, the IC-timer regulator increases the pulse width modulator (PWM) circuits "ON"-time so that the lamp is run constantly at the equivalent at the equivalent of a 1.8V battery voltage. It is pointed out that this increases both lamp and battery life.

I am a member of the Radio Society of Great Britain, and the article for the battery life extender circuit came from the February 2002 edition of RadCom, the Society's newsletter.

If you are going to use this information "somewhere else" would you be so kind as to give the RSGB, G. Stanforth and Electronics World their due credit.

With a bit of experimentation this could provide a worthwhile device to fit into your cycle lights battery compartment.

All of the components should be easy to locate, in a company like Maplin or you can help my friend Peter Thomas at JAB Electronic Components, PO Box 5774, Birmingham, B44 8PJ, FAX 0121-681-1329. Cheques or postal orders (payable to PA Thomas) Master card and VISA also welcome.