NXP

user Occupation hasn't been added

 NXP Semiconductors


  • Flood Alarm

  • Created: May 25, 2014

    • view1940
    • comment3
    • bookmark2
    • fork5

Description

No description available.

Summary

The alarm is built around two audio oscillators, each using two NAND gates. The detection oscillator is gated ON by a pair of remote probes. One of the probes is connect to the battery supply, the other to the input of one of the gates. When water flows between the probes, the detection oscillator is gate ON. The alarm oscillator is gate ON by the output of the detection oscillator. The values given produce an audio tone of about 3000 Hz. The detection oscillator gates this audio tone at a rate of about 3 Hz. The result is a unique pulsating note. Use any 8 ohm speaker to sound the alarm. The 2N3904 can be replaced by any similar NPN transistor. The circuit will work from any six to 12-volt supply.

3 Comments


palash_krazy

Guys, I have prepared this circuit. I had checked all the connections. All fine. But not getting the output as desired. I am supplying it with a 750mA 9 V power supply and Probes are dipped inside a cup of water. The speaker is not giving the alarm.

Posted: Sep 05, 2014


NXP

Just made a minor revision on the circuit, specifically on the connection of resistor R4.

Posted: Sep 29, 2014


NXP

Good day. The circuit has been re-design. Thanks!

Posted: Apr 18, 2016


Details


Components:

  • No components added

Tags:

Application:

Type: