Water Activated Alarm


Posted on May 19, 2012

The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and emitter and the transistor switches on. A larger current flows in the collector circuit enabling the 555 osillator to sound.


Water Activated Alarm
Click here to download the full size of the above Circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Dynamic to electret microphone circuit
Biasing Op-Amps into Class A
Infrared approach detector / sensor
Rs-232C Line-Driven Cmos Circuits
Frequency/Voltage Converter
Mosfet Buffer Amplifier Circuit
Ammeter and Precision Rectifier
DOGM128 with Arduino Hardware
building vu meter
protected
remote_control circuit
Electronic Lock
Audio Stereo Amplifer
Blocking material monitoring circuit



Top