simple circuit detects NO and NC connections

[mae2007]

Dear friends
please give me a simple circuit to detect NO and NC connection
thanks

 

[Pommie]

The circuit you are looking for is a battery and a light bulb.

Mike.

 

[mae2007]

thanks for reply
I will use the result signal to activate alarm
please send more details and schematic
thanks again

 

[bananasiong]

Please elaborate more.
You can use a battery, a switch (with NC and NO), and a buzzer. This is the simple circuit.

 

[mae2007]

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?

 

[KMoffett]

mae2007,

What voltage is the water sensor switching ON/OFF to the heater? AC? DC?

Ken

 

[mae2007]

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

 

[mae2007]

please see attached image

 

[KMoffett]

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?

Ken

 

[tresca]

If its digital out...

Use a pulldown resistor with your switch in series with Vcc and the resistor

When the switch is NO, you will receive 0v to your controller.
When the switch is NC, you will receive Vcc on your controller.