Extended Battery Life

[Bakofoil]

I have just built a vox switch and from a single 9v cell I canget arounf 130 hours on standby.

has anyone got any ideas on how to increase battery life significantly or any clever switching methods?

 

[Nigel Goodwin]

I have just built a vox switch and from a single 9v cell I canget arounf 130 hours on standby.

has anyone got any ideas on how to increase battery life significantly or any clever switching methods?

The obvious first answer is to reduce the current consumption of your circuit, if it's not designed for low consumption it could well be taking many times more current than it needs. Simply halving the consumption is likely to more than double your battery life. Try posting your circuit for suggestions!.

Another possibility is to switch the device on and off at fairly high speeds, again the circuit will need designing to work like this - but if it's ON for 10mS and OFF for 90mS, it should still detect any voice sounds - obviously it needs to latch ON when it detects a sound. This would increase your battery life by more than 10 times.

 

[zevon8]

Nigel makes an excellent suggestion. I have seen similar ideas based around a IR photoelectric type smoke detectors ( photo electric ones were easier to interface to since they didn't require the ionization chamber.) The smoke detector is used to control the main circuit, but instead of checking for smoke it powers up the main circuit, which in your case would be check for sound, then if no signal is present it goes back to sleep. The design also has built in battery check ( using a LED to load test the battery ) and alarm for low battery. The smoke detector itself can last nearly a year on a 9V battery, your circuit would reduce that, but atleast you get a complete controller for very little money. One such circuit is based around the MC145010 chip.

here is a link to the data sheet:
**broken link removed**