Double pulse unlock

There is a reply to this on the security forum from about 2-3 weeks ago.

A capacitor in series with the NC common and the relay coil  does the trick.

I get the timing I want with a 2400 mfd cap.

http://www.designtech-intl.com/Content/techsupport/documents/section04/note231.pdf

Check this link.

Regards

CalG

I bet this can be done with two relays as well.

The second relay wired to system voltage makes use of the NO function and injects a + signal while the - signal is in process.

By the time the things repeat, the activation signal is over.

I would need to play around at the bench.

Think about it.

CalG 

First pass says that if the second relay has it's coil energized thru a  suitable resister, it can be made to drop out as soon as the NC contact makes connection.

Too bad I don't know how to post a relay diagram here.

For those who would just advise to buy the accessory double pulse device,  Sometimes it is more fun to know than to have.

Regards

CalG

Tried to get this to work last night, but could only manage a buzz.

Capacitance can be a beautiful thing.

CalG