Latching interface logic required

Thread Starter

grahambollan

Joined May 27, 2007
2
The problem is to take a 9volt pulse from a clock and produce a 'loop' to operate a pump, this loop has to stay on until a second pulse from the same source signals a disconnect to the 'loop'. This process is repeated during the operation of a automatic sprinkler system where the clock output operates latching relay operated valves. I tried obtaining a single coil latching relay but to no avail. No other signals are involved, the 9volts pulse is battery derived and the loop will operate a relay in an artesian pump panel. Any bright ideas using common parts (I'm living in Turkey and component shops are thin on the ground) would be appreciated. Thanks for struggling through all this :)
 

Gadget

Joined Jan 10, 2006
614
This sounds like the classic Battery Operated Irrigation Controller, which uses Latching Soleniods to control water.
If this is actually the case, then the output from the timer is a +9 volt pulse which latches the solenoid on, and a -9 volt pulse which latches it off.
The reason for this is so that the battery isn't flattened holding the solenoid on during the irrigation period. It also means that if you have a decent enough supply that will handle holding a relay in an ON state for the pump, that you would be better to invert the negative pulse and therefore have 2 separate pulses to work a basic S/R flip flop. This would have the advantage of not allowing a confused output state in the event of error, reset or power cut.
 

Thread Starter

grahambollan

Joined May 27, 2007
2
Thanks to all of you for the ideas, the irrigation system is the right scenario, I'll now try the suggested solution. All I need is to find a component store in Turkey!
Good luck to you all!
 
Top