Flood alarm


Posted on Jun 7, 2012

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 connected to the battery supply, the other to the input of one of the gates. When water flows between the probes, the detection oscillator is gated on. The alarm oscillator is gated on by the output of the detection oscillator. The values given produce an audio tone of about 3000 Hz


Flood alarm
Click here to download the full size of the above Circuit.

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.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

High power bug
Digital Vacuum Gauge
TL072 op-amp configured as voltage comparator
diagram shows rather simple voltage
pipe descaler schematics
Soft Musical Telephone Ringers
Sound Blaster Microphone Preamplifier
simple usb avr isp compatible programmer
ujt triggering circuit
Game Circuits
Automatic distress alarm kit control circuit
Precision digital timing controller circuit (CC4013, CC440, CC4060, G1555)



Top