Using a Delay Timer as an Off Delay Timer

Note that the output will be on for one delay period when power is first turned on - if this is a problem, a bit more thought will be needed.

_{Well come on, it is Monday morning !}

thanks for that JohnDG i thought it came off a normal relay just wasnt sure.cheers

Good answers by JohnDG, giving what you were looking for obviously. You can add to the GA(Good Answer) i have given to the first one. (Pardon my presumption, you seem to be new to CR4, and i assumed you may not know this)

Taking off on the OFF delay thing, all delays are lost when power to the timer is lost, unless there is a massive capacitor providing adequate power to last till the set time is over....am i right here ?

i have used pneumatic OFF delay timers in many applications, especially where power-off-delay function was required. Quite good ones available. Electronic timers where signal-off-delay is enough.

Any views welcome.

" ...all delays are lost when power to the timer is lost ... am i right here ?"

- yes - that's why I specified "off delay (constant supply)".

If you fancy whiling away a bit of time, try designing out the OUTPUT ON period when power is first turned on (with the CONTROL input low) . Minimum component count, and no cheating with microcontrollers etc!

Mt knowledge of electronics is limited to its spelling.(though i go about mentioning STM and Microchip with a knowledgeable air to ensure that the vendors don't take shortcuts when designing μP devices ) Fortunately, i have two girls who are outstanding electronics engineers at my client's place, who will take care of the final performance.(Women are tougher to fool than men!)

i would love to try this as an exercise with my two lovelies when i visit Delhi next. Thanks for the exercise.

If the timer has a changeover contact, it is very easy to use. there will be a normally closed (NC) contact and one normally open (NO) contact. If you use an NC contact, it will become open after the time delay. If you use the NO contact, it will close after the delay. Hence you can choose between the contacts according to the application. it is so simple or am I missing something?

" ... am I missing something?" - yes. Please google "off delay".

I don't care about the guest.

But I just thought a timer would have 2 contacts.

NO & NC so surely a timer could be used either way on or off.

I looked at the question and I thought it was a bit strange because of the 2 contacts available and you can adjust as you want.

If you can explain to me the meaning of this timer off delay type then I might get your point but for me a relay will have 2 contacts with opposite functions.ON and OFF.

Do you understand the difference between an ON DELAY timer and an OFF DELAY timer? Please study the the diagram in post #11. If you are still in doubt, please Google "off delay timer", and read some of the links provided.

You could also have the on delay timer operate a coil that has the throughput voltage on normally closed contacts. When the timer times out and goes high, the coil will open the contacts on the relay and open the circuit.

Once again, an OP fails to provide certain specifics like: low voltage DC or high voltage DC intitiated? Is there another factor such as a control feature?

Meanwhile, we could play the conjecture game all day long.

It seems some of the respondents don't know about ON DELAY and OFF DELAY timers. Please may I clarify, with this diagram: