I want to fit a battery backup to a small audio device. Something that will charge a 7.2 volt Ni-Cad pack without damage no matter how long left on and run the device at the same time - and switch over automatically if power fails. Maximum consumption of the device is about 250 mA.
There appear to be 'millions' of supervisory chips out there and I was hoping someone could recommend one.
It sounds like a maintained emergency light would do what you want
Many cheap alarm clocks run on mains but with 9v PP3 backup...?
"Steve Walker" wrote in news: snipped-for-privacy@individual.net:
My extremely expensive radio alarm, wot loses it's brains if there's a power cut, and we have lots here just outside the M25, runs off a UPS consisting of a Maplin 6V 1.3 ah gel battery and a fully automatic charger, about 14 quid the pair.
It runs a lot cooler that the origial wallwart, so if 6V would do, it's an easy solution
mike
You dont need a chip to do that, just a trickle charger.
When it comes to recommending ICs, I'd definitely recommend sci.electronics,.design.
NT
A PP3 wouldn't last long enough - but I want a re-chargeable anyway.
Just a bit too big for what I want.
The SAB module from a burglar alarm bell will do the job, usually costs under a tenner.
Rgds
Andy R
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