Simple sleep timer circuit - how?

[Michael]

Hi,

I would like to build a *very simple* "sleep timer" circuit to incorporate
into a stereo system. It should switch the mains, and could even be in a
separate small box. The idea is to press a button to give me power for one
hour only.

Anybody built/seen anything like this?

Thanks,
Michael

 

[Joerg]

Hi Michael,

In the US these are sold in hardware stores. A knob is turned to
whatever time you want it on and it directly switches mains. Not much in
there except a mechanical timer and a switch. Possibly they also have
electronic ones. Mostly this is used to keep a fan on in the bathroom
after a, well, you know, or to keep a spa pump motor running for a
desired time.

Should be available in Australia as well.

Good Day, Joerg

 

[Ms_Squiggles]

Hi,

I would like to build a *very simple* "sleep timer" circuit to incorporate
into a stereo system. It should switch the mains, and could even be in a
separate small box. The idea is to press a button to give me power for one
hour only.

Anybody built/seen anything like this?

Thanks,
Michael

Years ago I had a clock radio that the radio had failed..... I removed the
radio circuit board and fitted a relay switching the mains, also a 3 core
mains lead. The relay coil was 12 volt, to suit the
switched DC voltage output from the clock circuitry. Where the speaker
used to be, I fitted a small size power point outlet....

Set the alarm and it would turn the hifi on at that time....
set the snooze to play the hifi for an hour....
use the radio on function switch to turn the hifi on for an indefinite
period of time.


Pip

 

[Michael]

Thank you.

Unfortunately the power outlet is hidden, but maybe the guts of the thing
could be put in a box with a power cord.
Hmmm.....

regards,

Michael

 

[Michael]

What a fantastic idea!

Thank you...

Michael

Years ago I had a clock radio that the radio had failed..... I removed the
radio circuit board and fitted a relay switching the mains, also a 3 core
mains lead. The relay coil was 12 volt, to suit the
switched DC voltage output from the clock circuitry. Where the speaker
used to be, I fitted a small size power point outlet....

Set the alarm and it would turn the hifi on at that time....
set the snooze to play the hifi for an hour....
use the radio on function switch to turn the hifi on for an indefinite
period of time.


Pip

 

[Martin]

Hi,

I would like to build a *very simple* "sleep timer" circuit to incorporate
into a stereo system. It should switch the mains, and could even be in a
separate small box. The idea is to press a button to give me power for
one hour only.

Anybody built/seen anything like this?

Thanks,
Michael

I would think that a simple 555 timer circuit would do this - set up as a
one shot timer. Plenty of circuits on the internet, just Google for 555
timer, and all parts available from Dick Smith/Tandy/Jaycar, etc, etc....
The timer circuit can drive a relay - if you use a relay with suitably rated
contacts then you could switch the AC....

I built a 24v timer to turn the light in the back of a rescue truck off
after 10 minutes - press a button and the timer starts, 10 minutes later it
turns the relay off and the light goes off. Ran the circuit straight off
the 24VDC power using a 12 volt regulator to run the IC and relay... You
could do similar for 240VAC as the curcuit doesn't use much power so a very
simple regulated power supply could be built to run the thing, if absolute
precise timing isn't needed (i.e. 1 hour +/- 1 - 2 minutes..)

To save some trouble I actually used the Jaycar timer kit and modified the
circuit a little to suit my needs. Probably have the schematic here of the
changed circuit, but try the Google trick first because 555 timer circuits
aren't very difficult at all..

Cheers

Martin, VK2UMJ

 

[Gregory Toomey]

Hi,

I would like to build a *very simple* "sleep timer" circuit to incorporate
into a stereo system. It should switch the mains, and could even be in a
separate small box. The idea is to press a button to give me power for
one hour only.

Anybody built/seen anything like this?

Thanks,
Michael

Theres a HUGE home autopmation industry that does this sort of thing.
Its a big seller in the US at http://www.x10.com/

For 240V you can try http://www.eon3.com/

gtoomey

 

[Lord-Data]

$29.95 at officeworks for a Belkin TimerCube ..

these have gone sellthru, which means end of line .. but most stores
probably still have stock at this point ..

 

[Unbeliever]

Thank you.

Unfortunately the power outlet is hidden, but maybe the guts of the thing
could be put in a box with a power cord.
Hmmm.....

regards,

Michael

Or maybe on the end of an extension cord? Look in the electrical section at
Bunnings, maybe even at Kmart. Leave the guts behind the safety rated
enclosure where they belong.

Cheers,
Alf.

 

[Michael]

I have been away for a week, and have come back to all these replies.

Thanks all for your suggestions. Ultimately I modified a clock radio by
replacing the dial lamp (9VDC) with a relay, switching 240V to a socket on
the back.

This works a treat, and gives me all the clock radio functions, but I am a
little uneasy about the safety rating, and will try some of your other ideas
as well. (instead).

Thanks again all of you,

Michael