JOHN T wrote in message ...
Russell Powell wrote:

If you've a permanent supply available, why run off of the
batteries in the first place? Place a diode between battery
output and permanent supply. Have permanent supply 9.7V
such that the diode is reverse biased while permanent power is applied.
When permanent power goes away, diode becomes forward biased.
Circuit operates off of battery supply.


--
sincerely,

Russell Powell

Artisan Components
SR. FAE - U.S. Central

469-438-6589

.................................................. ..........................
not good....some electrical fires that cause total distruction of the home
cause the electicity to go off long before smoke would get to the bedroom.
If you have a death wish go ahead and run the smoke detector off 110.
John

Keep reading. Russel is talking about the batteries kicking in after
the power goes out, therefore the smoke alarm should still work just
fine. On another note I would say that I am sick and tired of hearing
from fire officials that you absolutely have to buy a $05.00 battery
(my smoke alarm will only accept alkaline or lithium 9 volt batteries
and the alkalines just don't work for more than 5 months each)every 9
months or else you're doomed. My way will provide the ultimate in
safety as people often forget to change their batteries or just
disable the smoke alarm altogether because of the hassle of going to
the store to buy a battery that will probably never be truly used, at
least once a year. After all - it's such a hassle I am doing this
project aren't I?

Could someone here help me with nimh or nicad recharging specifics
(i.e. trickle charging and/or in the case of nimh smart recharging) so
I can make some headway in the project? Thanks for reading.