Help with time released lid

markuk75 said:

Good afternoon all my first post,
I have done a lot with RC stuff in the way of electronics,
but i have been asked to make a Autofeed for a hay box,
so been thiking of an electro magnet that hols the lid down then with a timer it releses the lid sounds easy,
but its in a field so really only have max of a 9v battery really.

So question what sort of timer could i use its only for a once open a day the eveing the next day it will be reset for that eveing, so only need 12 hr max really but 24 could be good,
also as only 9v battery really need a way for it to not use to much power as dont want to be changing the battery every other day,

but with the electro magent holding down the lid the whole time that would use a lot of power, so may be a solinod instaed to relase a lock?
hope that makes sense and any sugestions would be very much apreciated

thanks
Mark

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ZipZapOuch said:

9v battery? How about a bank of lead-acid batteries and a solar panel to recharge? A latching solenoid.
What safety mechanisms/procedures would you use to prevent animals from starving if the unit fails?

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ChrisP58 said:

I would suggest this type of latch.

It draws no power when holding. It will release with a pulse of less than a second.
Amazon link

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Pommie said:

Note: the small (pp3) 9V batteries are only rated at 0.5Ah and can't supply much current (1.5A is a lot).

Mike.

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ZipZapOuch said:

An Energizer Ultimate Lithium 9v can handle 1A continuous and 3A pulses aren't a problem (but not specified).

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Pommie said:

And an (insert any brand name) lithium battery is very expensive (Energizer PP3 being over USD10). I was talking about a normal (although still alkaline) battery. Do you really think the OP was specifying a Lithium battery? More likely a carbon zinc battery.

Mike.

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