switch or relay question! plz help

[jaygeorge1979]

Hey guys

I am trying to find a switch or relay type device that turns on when it senses a signal (like a relay) and routes a higher power source to the load (like a relay would) but i need something that will STAY on even if the initial signal is cut....in other words, a slight amount of power coming thru the wire is sensed by the relay and therefore it sends the higher power 12V power to the load....even if the first wire goes cold, the load still gets power...does this type of device exist? if my explanation was too confusing let me know and ill try and be more clear

Thanks

 

[mazurek]

what you want is a latching relay.

search on digikey for latching relay and look at the datasheet of one of the relays you find, the schematic will help you understand whats going on. There are two single or double coil types, again look at the datasheets for one of each type.

 

[jaygeorge1979]

thanks alot! thats exactly the kind of answer i wanted

woot

 

[ifrythings]

An SCR will do the same thing.

 

[jaygeorge1979]

SCR? what is this? is it like a relay?

while im asking questions, may as well ask this too:

do the relays need any type of grounding, for protection? i know there is a small voltage signal coming in that needs to be grounded out of the relay...then there is also 12V signal coming in that is being routed to the load depending on the relays position

so i guess im just gonna use extra thick wire on the ground to make sure its safe

 

[AndrewT]

Hi,
you can fabricate your own Latching Relay by interconnecting a pair of (or maybe it's three) ordinary relays together.

The extra relays are only carrying low level currents while the main relay has to be rated for your load.

There were a couple of threads that looked at a similar problem a year or so back. One was looking for a relay system to turn a push to make switch into a latching connection.

 

[jaygeorge1979]

thanks for the post andrew...ill search the forums and post back my findings