I want to design a thing as a boiler, I use a water sensor(mechnial) NO, when the water reaches to the required level the sensor becomes short , so the system makes heater to be ON, how can the system sense this short?
the voltage to the heater is 220 V AC, the water sensor isnot photosensor. it is a water buoy. it is NO. when the water reaches to the required level then the two wires(out from buoy) become short. I mind that I put 5 V DC on one wire and then connect these two wire to an AND gate. when the two wires become short so the AND output will be high. I take this output to control the heater via a relay connection. is it an logic,durable and safe idea??????????????
thanks
So you want to have the "float switch" continue to switch the heater ON and OFF, but want to add an alarm then the heater is turned ON. What is the voltage of the alarm? Or, do you want to provide a logic level (5V) signal to some other device for the alarm?