Hi - I am doing a bit of brainstorming for a current project and not finding an answer.
I want to know if there is any way to set up a 9v or 12v relay (or two) in such a way that once it is powered (and intended device activated) it will not turn off even once the relay activating switch is returned to the off position. Any insight would be appreciated.

 

Welcome to AAC!

They make latching relays.
http://www.omron-ap.com/service_support/FAQ/FAQ02822/index.asp

 

Or use a relay with an extra pair of contacts. Wire the NO switch to latch the relay once activated.

 

Hi - I am doing a bit of brainstorming for a current project and not finding an answer.
I want to know if there is any way to set up a 9v or 12v relay (or two) in such a way that once it is powered (and intended device activated) it will not turn off even once the relay activating switch is returned to the off position. Any insight would be appreciated.

Using a single actuating switch, the methods noted so far will turn the relay "on" but will not turn it off. Is that okay? Otherwise, another switch can be configured to turn the relay "off".

 

Thanks very much for the replies.
This info is terrific.
I am setting up an alarm system so, yes, I want the alarm to stay turned on once triggered.
I will set up a remote to arm and disarm.
But now I guess I also need a way to turn it off in the event of it accidentally being triggered ... I think the disarm button on the switch will take care of that.

 

Just add an normally closed push button on series with the relay coil.

Les.

 

Use a spare set of contacts to latch it, or use a Thyristor to trigger the relay, and put a NC switch in series with the coil..

 

Try this:

It's a double pole double throw relay. DPDT

 

Try this:
View attachment 195252
It's a double pole double throw relay. DPDT



That's terrific. Thanks heaps.

 

Hi - I am doing a bit of brainstorming for a current project and not finding an answer.
I want to know if there is any way to set up a 9v or 12v relay (or two) in such a way that once it is powered (and intended device activated) it will not turn off even once the relay activating switch is returned to the off position. Any insight would be appreciated.

Why don't you use an SCR? A relay is a coil, which is slow, takes current to activate. An SCR (Silicon Control Relay) is solid-state, instant, and stays latched until power is removed from Anode, Cathode, and Gate.

 

Magnetic latching relays can have two coils called set and reset. They are polarity sensitive. A permanent magnet can keep it in either state once triggered. The addion or subtraction of an additional magnetic field (usually a pulse) from a coil causes it to change states.

A multiple pole relay can use one pole to latch by continuously powering the coil. Interrupting power to the coil or briefly removing power, causes the coil to disingage. An SPST NO switch can energize the coil. Another SPST NC switch is in series with the coil. Pushing it, turns the relay off.

 

Why don't you use an SCR? A relay is a coil, which is slow, takes current to activate. An SCR (Silicon Control Relay) is solid-state, instant, and stays latched until power is removed from Anode, Cathode, and Gate.

Silicon Controlled Rectifier

... not relay.