Timer Circuit

[kb3zge]

Hello,

I need to build a circuit to open a relay for about 4 seconds at the top of every hour. This needs to trigger an event. I will be feeding dtmf tones to the trigger while the relay is open. Somehow I need this to go at exactly every hour. Someone please help,

Jim

 

[MikeMl]

One of these and a decoder or use it to trigger a 4 second one-shot.

 

[magvitron]

If you need an exact delay you can use controllers or something. if the timing is not that much of an issue , can use general purpose timers like 4060 or ne 555(and some circuitry) for the delay. please be elaborate in the problem so everyone can help you out.

 

[BeerBelly]

My clock on the wall chimes every hour. Use the chime to trigger the 4 second timer and DTMF circuit.
Maybe a micro-switch on the birds door.

 

[BioniC187]

I don't think a 555 is stable for an hour. To get that one hour delay, use a PIC.

Lol, before reading BeerBelly's post, i said to myself, get a cheap cellphone, set alarm to go off every hour, and use the output from the speaker as signal to trigger your relay. But, such a task, I only mentioned it coz my thought was similar to his post

 

[MikeMl]

I don't think a 555 is stable for an hour....

That is why we both suggested the 4060. With a crystal, it would be as stable as any watch/clock. We suggested using the 555 only to get the 4 sec period...

 

[BioniC187]

Oh dear, sorry about that. I was in a rush, i didn't read correctly