In article ,
wrote:
Hi,

I have a camera hooked up to a 9v battery and want to be able to use a
'timer switch' to turn it on at a specific time ( like the ones you
plug into a wall socket and then plug in your light socket and get it
to switch your light on automatically at a certain time when your away
)

Is there such a thing that can do this with a battery as the power
source?

a battery powered alarm clock with a few modifications could do that.

what you'd need to do is remove the speaker and put a little amplifier
in there to drive a relay.

..
.. something like this maybe to supply +ve
.. R1 |
.. ,-[100k]-----+---+--- to relay
.. | .--+-|-'
.. | /' | D4
.. 100p | |/' `-------- to relay
.. clock's o--||-+---+--[10k]-(-----| BC549
.. speaker terminals | `-||-+--' |\|
.. o--. `-[100K]--| ~~\
.. | | `|
.. diodes are 1N914 etc `------------+----||-||-+---- to supply -ve
.. except D4 which is 1N4001 or similar
..

supply voltage should be chosen to suit the relay.
R1 may need to be increased.
at the point labeled ( the wires cross.

no guarantees but it should work...
--

Bye.
Jasen