Low standing current countdown or wireless switch

I'm looking to activate a single circuit on an animal collar after about 2 months in order to cause the collar to fall off. Wireless switch receivers require 4-8 mAH drain to stay responsive which requires too much battery weight over a multi-month period of time. A very low power countdown activated switch only needs accuracy within a few days since the telemetry system will still be functioning at collar drop-off and will enable us to retrieve the collar. Any lightweight, low-drain suggestions as a solution?

Thanks,

Pete

just would like to know what type of battery you plan on using. could make a difference in application. if using L-poly and you plan on retrieving it there were be no carbon foot print to think of. and the life would last longer. then it could be set a higher volt battery and smaller cell can be used with a simple volt diver. just make sure you use the right combo of for you amp out put. john

Hi John,

Yes I'm planning on using an L-poly to power the countdown switch. The problem is that I'm a biologist, not an engineer, and haven't been able to find any kind of off-the-shelf timer switch that is long duration and small, let alone low drain. ANY suggestions would really be appreciated.

Pete

Hi Pete,
For any hobby or professional that plays with electronics it is not a big problem.
If you can tel where you live and or do your research maybe somebody here that lives close by can help you.

Personal for me i think a pic (that is a small micro controller) can be used it has a sleep function where its current use is extreme low.
And it can be programed to activate the transmitter on a daily base for a few seconds for mapping tracing on a time that you will know it, if required.
And after a programmed time to release and transmit in a faster time frame.
There must be a complete discussion to find out all the functions that you want and the budget that you have also very important the final weight, size and environment that it will be used.

You can also check sites like the following.:
"movebank a wildlife tracing bank(movebank)":https://www.movebank.org/

"a professional sale shop(a internet shop)":http://www.atstrack.com/Type-3-Tracking-Mammals.aspx?gclid=CI_ik4zPxrQCFTDMtAodrwYA8Q

It can help to talk with the above sites maybe they have what you need.

Best regards and a happy new year
Peter Evenhuis

Hi Pete. I have a possible solution which I have envisaged for a different purpose but it should work. What I believe you need is a timing circuit which opens the receiver on the collar for a few seconds to every two months. The transmitter would also need a similar timer. Depending on the accuracy you can get, you may need to have the receiver open for even an hour or so. If your timing circuit is good enough then the open time of the receiver can be reduced. Ideally the receiver should be open some time before the transmitter activates and stays open for some time after the transmitter has finished its command. The collar would need likely a crystal oscillator and CMOS dividers. The 32 KHz watch crystals can oscillate for a year or more in a watch so this is likely to be a satisfactory clock generator.
I hope that this helps.
Please forgive late reply as the internet has been down here for about a week.

Hi Rodney,

Thanks for your suggestion!

I'm interested in a VERY SIMPLE stand alone device/circuit that would be totally independent of our other telemetry. Ideally I would program the circuit to turn a switch on approximately 60 days after initiation. I just desire minimum countdown current draw and a single off to on switch after the 60 day period with accuracy needed to within a day or two.

Any other quick solutions from the forum would also be very much appreciated.

Happy New Year to both you and the rest of the Forum!

Pete

I tend to agree with peter and rodney Ideally something such as pic micro with sleep function operated from typical watch batteries If you opted for surface mount minimal components Could use the internsl RC oscillator no real external components or possibly external realtime clock for accuracy giving you wake up on interrupt to operate your latch mechanism Look at the microchip website I see that some new devices have just been launched so it may even pay to drop them a line Ive always found they are extremley helpfull and knowledgeable

In fact if you mention that this is for research and can validate this with obvious written evidance Microchip may even supply you with ready made preprogrammed sample ready to go, You can but ask They have sent free samples to myself in the past where technical difficulties have arised all the way from the states So no complaints about microchip what so ever Very helpfull company

National semiconductor being another company on same par as microchip Also extremely pleasant and extremley helpfull always have been