# Zero Voltage input to latching relay or controller needed

**URL:** <https://forum.digikey.com/t/zero-voltage-input-to-latching-relay-or-controller-needed/21759>\
**Category:** Relays\
**Tags:** electromechanical, relays, part-identification\
**Created:** [April 21, 2022, 3:19pm UTC](https://forum.digikey.com/t/zero-voltage-input-to-latching-relay-or-controller-needed/21759 "2022-04-21T15:19:44Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jasont](https://avatars.discourse-cdn.com/v4/letter/j/df705f/32.png) [@jasont](https://forum.digikey.com/u/jasont)\
**Post date:** [April 21, 2022, 3:19pm UTC](https://forum.digikey.com/t/zero-voltage-input-to-latching-relay-or-controller-needed/21759/1 "2022-04-21T15:19:44Z")

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We have a device that has a zero voltage relay output that does a pulses closed and then back off again. I need get to a latching output, and have access to 12vdc.

We are looking of a relay or device that can be powered by 12vdc, sense the closer pulse of the zero voltage relay (dry contact, can not take any voltage by what we are being told), and when the pulse is sensed close other contacts. On next pulse from zero voltage relay opens back up the contacts. (Latching open and closed back and forth with each pulse).

The contacts that it is closing needs to be rates for 12vdc or higher 1amp or higher.

Any assistance would be greatly appreciated.

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**Author:** ![rick\_1976](https://sea2.discourse-cdn.com/digikey/user_avatar/forum.digikey.com/rick_1976/32/1571_2.png) [@rick\_1976](https://forum.digikey.com/u/rick_1976)\
**Post date:** [April 22, 2022, 3:43pm UTC](https://forum.digikey.com/t/zero-voltage-input-to-latching-relay-or-controller-needed/21759/2 "2022-04-22T15:43:39Z")

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Greetings,

Someplace or another, there should be specific limits stated as to the electrical capabilities of your dry-contact signal source; imposition of _some_ level of electrical stress is necessary to use it as a signal source, and knowing what is and isn’t permissible there is necessary if one’s going to do things thoughtfully.

You should also characterize the load you want to ultimately be switching, since that’s important to choosing an appropriate relay. You have one signal, a 12VDC source, and desire a latching function; you’re therefore looking for a single-coil latching relay with a coil rated for 12VDC. There are some signal-level products in stock meeting that description [here](https://www.digikey.com/en/products/filter/signal-relays-up-to-2-amps/189?s=N4IgjCBcoOwExVAYygMwIYBsDOBTANCAPZQDaIAHDBQGwUgC6hADgC5QgDKrATgJYA7AOYgAvoRowArIhApIGHAWJkQAZhpr4EJiDYdu-YWMIBaBNDlReAV2UlI5GQ1HiQF8j1yZ0AT0aiQA), and others better suited for power switching applications [here](https://www.digikey.com/en/products/filter/power-relays-over-2-amps/188?s=N4IgjCBcoGwOwFYqgMZQGYEMA2BnApgDQgD2UA2iAMwxVwBMEAusQA4AuUIAyuwE4BLAHYBzEAF9xxehRDZM7FAAthIgAR988gJ4gm4oA).

Depending on the limitations of your signal source and requirements of the chosen output device it may be possible to drive the output relay directly, though it’s likely also that some sort of drive transistor may be needed.