28 day timer

[dryden_burton]

hello fellow electronics personel I need some help. I need a 28 day timer with adjustable run time. I also need a 7 day timer with an adjustable run time. I would prefer a kit that just needs to be assembled. thanks.

 

[panic mode]

what resolution?

 

[dryden_burton]

what is resolution? I want the 28 day timer to turn on every 28 days and run for an adjustable time 1 to 10 min. I want the 7 day timer to turn on every 7 days and run for an adjustable time 1 to 10 min. thanks

 

[Nigel Goodwin]

what is resolution? I want the 28 day timer to turn on every 28 days and run for an adjustable time 1 to 10 min. I want the 7 day timer to turn on every 7 days and run for an adjustable time 1 to 10 min. thanks

Resolution is how accurate you need it to be - so a resolution of 5 mins would be accurate to within 5 minutes, and so on.

The lengthy delays really call out for a micro-controller solution, and I would advice using a crystal oscillator on it, rather than the simple internal oscillators used in some.

However, you can generally buy cheap simple timers, micro-controller based, which would certainly do for your 7 day requirement.

 

[Optikon]

what is resolution? I want the 28 day timer to turn on every 28 days and run for an adjustable time 1 to 10 min. I want the 7 day timer to turn on every 7 days and run for an adjustable time 1 to 10 min. thanks

Resolution is how accurate you need it to be - so a resolution of 5 mins would be accurate to within 5 minutes, and so on.

Strictly speaking this is not true. Resolution is _theoretical_ programming step size. i.e. increments of 5 minutes. Accuracy how close to the 5 minute programming time you actually get. Potentially one can design a timer with 5 minute resolution and an accuracy of 1 second. A 5 minute interval could actually be anywhere from 299 seconds to 301 seconds.

resolution and accuracy are NOT the same thing.

 

[Nigel Goodwin]

resolution and accuracy are NOT the same thing.

Sorry! - I meant "setting accuracy".

 

[audioguru]

Maybe there is a manufactured medical timer for a 28 day cycle. It would be used by women as an alert to begin taking birth control pills each month or something. :lol:
You might need to add your variable shorter timer to its output.

I don't know if there are pills that are taken every 7 days, but I've heard that some frail old men (not me, I'm a teenybopper with grey hair) need a testosterone injection weekly.

 

[Mike - K8LH]

and run for an adjustable time 1 to 10 min.

What do you mean by "run"? Turn on a relay output for 1 to 10 minutes? Turn on a klaxon for 1 to 10 minutes?

Do you want to set the date, time, output time & duration with switches and a display on the "timer" itself, or can you tolerate a simpler and less expensive design that plugs into a PC serial port to set those parameters?

This really would be a good microcontroller project... I'm sorry to say I haven't run into any kits like this though... Have you searched for something like this already?

Regards, Mike

 

[dryden_burton]

by run time i mean it turns on a relay for 1 to 10 min then shuts off. It only needs to be acurate to the day if its off by a couple of hours it doesn't matter as long as it doesn't turn on 28 days then 27 then 23 as long as its every 28 days same with the seven day timer every 7 days.

I was thinking along the lines of a sprinkler system timer, one that i could program to run valve #1 once a month. and valve #2 once a week using the same timer. a link to a timer that can be programed like this would be nice. thanks.

 

[dryden_burton]

I found this, will it work it says Repeating day cycle allows irrigation frequency from 1 to 28 days. **broken link removed**

 

[audioguru]

:lol: Nice timer. :lol:

 

[dryden_burton]

:shock: yes it is a nice timer but will it work? also the output is 26vac I need dc for a relay (normal relay) so i need an ac relay right. or will the timer even work :?:

 

[Optikon]

:shock: yes it is a nice timer but will it work? also the output is 26vac I need dc for a relay (normal relay) so i need an ac relay right. or will the timer even work :?:

Can you have that relay switch in/out another one of your choice so you can handle to particular load you need? In my opinion, the best solution is to buy the timer function and add a second relay for your particular load. It's the fastest way to being done anyhow.

 

[dryden_burton]

you mean have the relay hooked to the sprinkler timer turn on another bigger relay, right. (Repeating day cycle allows irrigation frequency from 1 to 28 days.) does this mean I can program the timer to turn on every 28 days?