Yelping-siren


Posted on Aug 11, 2012

Unijunction transistors Ql and Q2 are both connected as relaxation-type, sawtooth oscillators. Transistor Ql is the low-frequency control oscillator and Q2 is the tone generator. Sawtooth waveforms are produced at the emitter terminals. Without R4 connecting the two emitters, each oscillator operates independently, with its frequency determined mainly by the rc time constant. With the values shown, Ql operates from 1. to 1.5 Hz and Q2 operates from 400 to 500 Hz.


Yelping-siren
Click here to download the full size of the above Circuit.

When R4 is connected between the two emitters, it couples the low-fr€quency sawtooth from Ql directly across capacitor C2. That coupling causes the frequency of the tone generator to increase, along with the rise in sawtooth voltage from Ql. The tone generator"s frequency drops to its lower design value when Cl discharges and produces the falling edge of the sawtooth.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Solar charger for lead-acid batteries
RS485-like multi-drop bus
Remote-sensor-loop-transmitter
Water Activated Sensor Alarm Using 555 PCB
6V Ultra-Bright LED Chasers
Display Text on an HD44780 LCD with an Arduino
direction detector decoder
HF linear amplifier circuit
grundig 5040w3d circuitry analysis
52W SMPS AC-DC Adapter



Top