Timed battery powered device

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thoiter
Posts: 2
Joined: Wed Jan 03, 2018 9:53 am

Timed battery powered device

Post by thoiter » Wed Jan 03, 2018 10:08 am

I need to build a small setup which will operate a battery powered device (2 x AA batteries) on a battery powered timer. The timer needs to provide current for a few 20 minute intervals in an 8 hour period. Nothing can be mains powered or greater than 9v batteries. I considered using a product called Tethercell which is a bluetooth battery holder that can be remotely controlled from an iphone with timer software. However it's proving very hard to get hold of this item, so I thought I'd look into building my own solution. I have very little electrical expertise other than being able to solder :)
If anyone is able to offer any advice on what components I could use and how to construct this I'd be very grateful.

David
Posts: 165
Joined: Sun Oct 04, 2015 6:18 pm

Re: Timed battery powered device

Post by David » Wed Jan 03, 2018 12:48 pm

If the 20 min periods are regular within the 8 hours a simple CMOS 555 device should be easy and reliable. Search Google for "CMOS 555 circuits" - you will find a huge number and there should be many that will work for you. If need be, you could have two timers - the second being triggered by the first, which would allow you independently to adjust time between on periods, and the length of the on period.
Hope this helps

thoiter
Posts: 2
Joined: Wed Jan 03, 2018 9:53 am

Re: Timed battery powered device

Post by thoiter » Fri Jan 05, 2018 9:51 am

It helps a lot. Thank you very much.

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