Air-motion detector


Posted on Jul 11, 2012

Sensing circuit detects either steady or fluctuating air flows. The heart of the circuit is a Radio Shack piezo buzzer (P/N 273-060) and an LM324 quad op amp. (Red wire from the piezo element connects to capacitor CI, and the black wire to ground) When a current of air hits the piezo element, a small signal is generated and is fed through CI and R1 to the inverting input (pin 2) of one section of the LM324. That causes the output (pin 1) to go high. Resistor R3 adjusts sensitivity


Air-motion detector
Click here to download the full size of the above Circuit.

The circuitcan be made sensitive enough to detect the wave of a hand or the sensitivity can be set so low that blowing on the element hard will produce no output. Resistor R2 is used to adjust the level of the output voltage at pin 1. The detector circuit can be used in various control applications. For example, an SCR can be used to control 117-volt AC loads as shown in A. Also, an NPN transistor, such as a TIP29, can be used to control loads as shown in B.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Speed Controller for brushed electric motors
Parametric SubWoofer Equaliser
PC DATA LOGGER
PC ROM emulator circuit
Capacitor Discharge Ignition
Light-sensitive-audio-oscillator
Dialed-phone-number-vocalizer
Solid State Tesla Coil/High Voltage Generator Circuit
VU LED Indicator Schematic
digital isolation up to 100
Mosfet Amplifier Circuits
Single Pentode Wien Bridge Oscillator
A touch switch lighting circuit
555 Dream lantern control circuit diagram



Top