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I would like to get my hands on a mechanically-set timer (wind up is fine, so that it's self-powered) which sends a small electrical pulse to a mag-lock once the timer goes off, thus causing the mag-lock to open. Is there anything out there that does this?

If not, what would be the cheapest / easiest way to replicate such function, i.e. some mechanical way to produce a small electrical impulse once a mechanical timer finishes. I don't mind electronic methods, but since this is for heavy outdoor use I'd prefer a purely mechanical setup.

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closed as off-topic by Wasabi, wwarriner, hazzey, Ethan48, mg4w Jun 16 '16 at 11:10

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about engineering, within the scope defined in the help center." – Wasabi, hazzey, Ethan48, mg4w
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ Just buy an outlet timer and plug whatever electronic lock into that. $\endgroup$ – sintax Jun 14 '16 at 16:55
  • $\begingroup$ Why the downvote? My understanding is that this is on-topic? $\endgroup$ – Engineer Jun 14 '16 at 17:12
  • $\begingroup$ @ArcaneEngineer - I suspect the down and close votes are because this is a bit of a fishing expedition. StackExchange Q&A works better with focused Q&A instead of broad reaching "Is there anything out there that does this?" type questions. $\endgroup$ – GlenH7 Jun 15 '16 at 0:13
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In principal it should not be very difficult to adapt an off the shelf mechanism like a mechanical alarm clock or kitchen timer. They will already have some sort of latching mechanism to activate the bell after the elapsed time so it should be a simple matter to adapt this to close an electrical contact.

Having said that I'm not entirely convinced that a mechanical system is necessarily going to be any more rugged or reliable than an electronic one. As already mentioned in other answers a mag-lock will need a reliable power supply and a timer circuit is simple to achieve with either digital or analogue electronics and can be potted of placed in an IP rated enclosure to make it pretty much indestructible compared to any kind of clockwork system.

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  • $\begingroup$ Thanks, Chris. I do grudgingly accept the idea that cheap consumer electronics may be cheaper and easier to achieve this with. However it just seems like such a waste, if that latching mechanism could strike a spark or what have you (piezoelectrics?). However I have no idea if the electrical qualities of such a pulse would be suitable; almost certainly some kind of transformation would be required before it could trigger the mag-lock successfully? $\endgroup$ – Engineer Jun 14 '16 at 17:27
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    $\begingroup$ You absolutely could do it if that is the approach you want to use. For example the barrel spring used to ring an alarm bell could easily generate a moderate current if coupled to a dynamo. One example is the 'exploders' used to detonate explosives. arbra.co.uk/hand-generated-exploder $\endgroup$ – Chris Johns Jun 14 '16 at 17:33
  • $\begingroup$ Re the mag-lock, I asked on the EE chatrooms about power requirements, yesterday. The guys suggested that, "There are pretty cheap permanent-magnet locks that require only a small pulse to disengage." Since this is to keep birds in, that sort will be sufficient, i.e. a current is not needed to keep the hatch closed. I'm still concerned about pulse transformation, but I should probably query the EE guys about that. The dynamo idea is most pertinent here - thanks - I will look into it and bug you on chat if necessary. ;) $\endgroup$ – Engineer Jun 14 '16 at 17:37
  • $\begingroup$ Just got your comment update - the link should help - thanks! $\endgroup$ – Engineer Jun 14 '16 at 17:41
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    $\begingroup$ It may also be that a purely mechanical system would be easier. For example you could have a clock like mechanism which is directly coupled to a simple latch. $\endgroup$ – Chris Johns Jun 14 '16 at 17:55
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A mag lock typically uses 12 volts at low current to power the electromagnet to remain locked. The unlocking mechanism trips the power to the electromagnet. Mechanical delay relays do exist, but you would need one that has a normally closed relay that would be opened by the mechanical delay.

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