control circuit "and gate"?

[Beerman]

I want to operate a 12v ac relay from 6 12v ac supplies (solenoid valves), the relay would operate a pump, when any of the valves were open.

Any advice would be apreciated

Thanks in advance

[Simon (Webmaster)]

Hi

Probably the easiest way is to have 6 identical relays, with the coil of each one connected to one of the 12V supplies, and all 6 sets of normally open contacts connected in parallel, powering the pump. This way if any of the relays is on (corresponding solenoid on) the pump will be powered.

If you want a more electronic solution you could use an OR gate to control a single relay. However you would need to rectify each of the 6 inputs (since they are AC), need a drive transistor on the output since the OR gate would provide insufficient power to drive the relay coil directly, and you would need a permanent 12V DC supply (or thereabouts) to power the circuitry.

[Beerman]

Thanks for that Simon

Any Idea where to get the relays from?

[Simon (Webmaster)]

Sorry for the slow reply. Farnell, RS or possibly even Maplin should have suitable relays. You want AC coils, not DC. Farnell's website is www.farnell.co.uk, a search gave me:

http://uk.farnell.com/jsp/search/browse ... le%3Den_UK

Not sure if the link will work for you - search for AC relays, click 'Power - General Purpose' then use the search filter to select the required coil voltage. Select a relay from the list that states it is '12VAC'.