A small timer required.

[Orangewhip]

Hello, I have a requirement to create a timer that will run automatically without continuous attention.

I have an aircon that is on a 4hr timer. Which means it will run for 4 hours and I have to get up and flick a switch to reset the timer (flick off and on to restart timer (imagine like in a hotel how you need to put a card in to use the lights etc)).

There are 2 wires connected to the switch with very little power running through. I have no access to the mains power for the aircon or the electric controller on the board. But I can access the switch and wires related to it therefore If I can create some sort of timer that will toggle off for a minute or so then back on for 1-4 hrs that would be good.

What I imagined was like a clock with 1 wire connected to the hour hand and then another wire connected to a metal ring (with small split) attached to the face of the clock and as the minute hand goes around it maintains a circuit but as it hits the split it cuts the circuit resetting the timer.

This isn't the best idea so I need some more ideas.

 

[Harald Kapp]

You could use a timer module with relay output similar to this one in this application.

 

[turbogt16v]

Do you need it to run always,or just partially

 

[Orangewhip]

I would need it to run as long as I want to keep the aircon running.

basically i like to run my aircon all the time except when i choose to turn it off.

the above timer module is a little out of my knowledge range.

to describe a bit better. i have a positive and a negative wire that somehow retriggers the timer when i break the circuit. however if i leave the circuit broken the aircon will stay off, i need to break the circuit then complete the circuit to retrigger timer and turn the aircon back on. its a 4hr timer, if you toggle off and on at the switch it will reset .

 

[Bluejets]

Does the existing timer have to time out before re-triggering or can you re-trigger it (break then make again) at any time in the 4 hours , allowing another 4 hour session?

If the latter, (as Harald has already pointed out) any simple astable 555 timer module off ebay with a relay output should suffice.

 

[Orangewhip]

it can break and remake anytime. I will look at a 555.

 

[Orangewhip]

can only seem to find very short timers. 10s 60s and 120s. that would be cycling the aircon on and off to regularly and probably cause damage

 

[AnalogKid]

Do you want to a) electronically push the button once every 4 hours, or b) turn off and turn on the entire unit once every 4 hours.

For either one, you can get a programmable timer at WalMart, and have it turn a relay on and off. There is a bit more to it, but that is the basics.

ak

 

[turbogt16v]

can you please take picture of that swich

 

[Bluejets]

can only seem to find very short timers. 10s 60s and 120s. that would be cycling the aircon on and off to regularly and probably cause damage

Who knows. Without any circuit it is not possible to say really. I was just going on what you said ie a reset. In some instances if the unit timer was already running and received a reset, it would just stay on. In that case, 1 minute, 5 minute, 10 seconds, would be irrelevant.

 

[BobK]

What happens if you push the button while it is still running? Does that really cause it to cycle off and on, or will it continue to run and give it another 4 hours? If the latter, the timer can be anything less than 4 hour to keep it running.

Bob

 

[Orangewhip]

if i toggle the switch off the aircon turns on until I toggle the switch back on. when switch is on aircon is on. when switch is off aircon is off. if switch is on for more than 4hrs aircon turns off. I then toggle switch to off position and then to on position and timer resets and aircon turns backon. if I toggle switch of and on before 4hrs aircon will turn off for however long I toggle the switch off for then back on when i toggle to on. i just need a timer to replace the switch to do the off\on autimatically. even if it was every hour or so.

 

[Bluejets]

if I toggle switch of and on before 4hrs aircon will turn off for however long I toggle the switch off for then back on when i toggle to on. i just need a timer to replace the switch to do the off\on autimatically. even if it was every hour or so.

OK...then get a 1 hour unit similar to the one Harald referred to.

 

[Orangewhip]

Ok i will look fora 555 timer i na 1hr setting. thankyou