The very real benefit of using a mechanical timer instead of a typical electronic timer is that a short power failure that might not even be noticed will delay the cycle only the length of that outage time. A non-battery backed-up electronic timer may simply reset, or totally forget the time cycle programmed. That happened to me once. An overnight power glitch reset the motel alarm clock that was missing the backup battery.

 

A non-battery backed-up electronic timer may simply reset

Smart plugs do not have that problem, as their APP timing program is in the cloud.

 

Smart plugs do not have that problem, as their APP timing program is in the cloud.

That is an interesting assumption. BUT consider that any interacton with any "cloud control" must include two-way communication, and that both ends of that communication link must have local power sources. Cloud communication is not "telepathic", and we all should be very grateful for that limitation!!

 

I need to build a timer circuit that works for 15 to 30 minutes every day , which means that it should be off for almost 24 hours and then it is on only for 15 minutes then it is off again

$ 3.38
CN101A Timer Switch AC/DC 12V 24V 110V 120V 220V 230V 240V
Digital LCD Power Week Mini Programmable Time Switch Relay 8A to 16A

 

That is an interesting assumption.

Not an assumption, it's a fact.
When power goes out and returns, all my smart plugs and switches continue with their timing programs.

interacton with any "cloud control" must include two-way communication, and that both ends of that communication link must have local power sources.

True.
BUT the cloud seldom loses power, only my local power does, but very infrequently.

 

My preference is local control with local hardware. Much more private and in my opinion itwould be more controllable.

 

My preference is local control with local hardware.

$ 3.38
CN101A Timer Switch AC/DC 12V 24V 110V 120V 220V 230V 240V
Digital LCD Power Week Mini Programmable Time Switch Relay 8A to 16A
View attachment 370264

Can hardly beat a battery powered timer/switch. I currently have a battery powered single zone timer running a garden hose to water a fairly new tree. One that is struggling because of drought and reduced allowance to water grass.

 

My preference is local control with local hardware. Much more private and in my opinion itwould be more controllable.

Well, I'm not much concerned if someone discovers my smart-plug timer settings.

And HOW is a local control timer more controllable?
I can program any of my smart-plugs' timing to any sequence of on-off cycles, and can also turn them on or off or for a set time manually from my cell-phone.

 

Can hardly beat a battery powered timer/switch. I currently have a battery powered single zone timer running a garden hose to water a fairly new tree

And how long does it take to notice that the battery has gone dead?

 

24-Hour Indoor Plug-In Basic Mechanical Timer

I would suggest as was suggested by Mr. Chipps in post #10. They cost about $6.00 USD. Available from just about any home improvement store.

Ron

 

30 posts later, TS has not said what he is switching. Does he want contact closures or switched AC power out?

 

And how long does it take to notice that the battery has gone dead?

Тimer #24 contains inner rechargeable battery,
which is automatically charging from power line.
So timer still working during 60 days of absent
power in line.

 

If you can live with an approximate on time and once every 12 hours how about a 1.5V quartz clock movement with an hour hand fettled to cut through a photo interrupter? Combined with a light sensor could respond only when it’s light or dark

 

This application is precisely what an Arduino was designed for. I'm not certain that your contention that they are "complicated" is a defensible position. If you still think so, I would be interested in your particular reasons including personal limitations of which I might be unaware.

CERTAINLY an Arduino timer IS COMPLICATED! It must have a specific LOW VOLTAGE and STABLE DC supply voltage, and for other than a low power, logic level control signal, it must have an output interface device, either relay or solid-state. In addition, it must be setand programmed from some sort of digital device, such as a computer or aphone?
THe device presented by DANKO in post #24 is very interesting, but an equivalent device at my local home improvemment store sells for about ten times that price. Besides that, for most applications the arduino PCB must be mounted and packaged, not just hanging by it's connction wires in an experimenter's setup on a work-table.
As always, it is the details that are the bigger challenges.

 

CERTAINLY an Arduino timer IS COMPLICATED! It must have a specific LOW VOLTAGE and STABLE DC supply voltage, and for other than a low power, logic level control signal, it must have an output interface device, either relay or solid-state. In addition, it must be setand programmed from some sort of digital device, such as a computer or aphone?

It's a pity. If the only tool you have is a hammer, I suppose everything needs to look like a nail.

 

I do not recall much discussion of what sort of power or function is to be controlled, nor any other details except on and off. Is it controlling an LED or a space-heater?? The switching scheme requirements are rather different.

 

It's a pity. If the only tool you have is a hammer, I suppose everything needs to look like a nail.

Really? Have you seen my tagline - ?

"I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail."

- Abraham Maslow, Professor of Psychology at Brandeis University
"The Psychology of Science: A Reconnaissance", 1966

ak

 

And how long does it take to notice that the battery has gone dead?

That depends on the load. I used to have controlled sprinklers that were controlled by battery powered timers. Some of them ran on a 9V battery, others are currently running on two AA batteries. They activate the sprinkler by a latching solenoid, which means, aside from running the timer, it only takes a very brief pulse of energy in one polarity to open the valve. Then when the time period is up it takes a second pulse of energy in the opposite polarity to close the valve. I've run them two spring/summer/fall seasons (two years) before needing to replace a battery.

Since we still don't know what the TS is doing we can't give a definitive answer to the request. It's been a few days since the TS responded, (see post #3) so for now we have to wait and see what is needed.

Ghina Bayyat What is the project?

 

The failure mode of some 9 volt batteries is an increase in internal resistance, with the no-load voltage hardly changing at all. So the timer can keep timing but the output circuit would not function. That can be very unfortunate !!!

 

The thread starter hasn't been back and no clue what he is switching be it load current or load voltage. That, as mentioned, would help considerably. Next up no clue as to what the thread starter has available? I like my smart plugs and they work just fine for applications like this but again, no clue what the thread starter has available. We get so many threads where thread starters leave out critical information making it pretty difficult to make good suggestions.

Ron