Hello Electronics gurus!
I have a diesel tractor that has a magnetic reed switch in the fuel tank to indicate low fuel. This switch is open when there is fuel in the tank, and closes when the level drops below it. When this switch closes a 12v relay is energized to disengage the fuel control and shuts off the engine. The problem is, sloshing fuel causes the float switch to intermittently open/close, which shuts off the engine! What I am looking for is a time-delay circuit, so that when the float switch closes a delay of 10-20 seconds starts. If the switch STAYS closed longer than 20 seconds, the delay timer energizes the 12v relay and kills the engine. If the float switch OPENS during that 10-20 seconds, the timer needs to reset. My electronics experience is limited, and I have looked at perhaps a 555 chip to do this, but I cannot figure out the reset portion at all. Could someone show me a circuit diagram to do what I need? Any and all help is greatly appreciated!
Andy
I have a diesel tractor that has a magnetic reed switch in the fuel tank to indicate low fuel. This switch is open when there is fuel in the tank, and closes when the level drops below it. When this switch closes a 12v relay is energized to disengage the fuel control and shuts off the engine. The problem is, sloshing fuel causes the float switch to intermittently open/close, which shuts off the engine! What I am looking for is a time-delay circuit, so that when the float switch closes a delay of 10-20 seconds starts. If the switch STAYS closed longer than 20 seconds, the delay timer energizes the 12v relay and kills the engine. If the float switch OPENS during that 10-20 seconds, the timer needs to reset. My electronics experience is limited, and I have looked at perhaps a 555 chip to do this, but I cannot figure out the reset portion at all. Could someone show me a circuit diagram to do what I need? Any and all help is greatly appreciated!
Andy