recent searches: wave generator, metal detector door, temperature system, taser/alarm system, guitar tuner, ic flasher circuit, static Battery Charger, primary resistor starting, 6v Dc variable Power supply, conponent of Simple Lie Detector,

How to build Electronic Canary

this circuit diagram belongs to Timers category.

Feeling chirpy? Attract new friends with this modified hartley oscillator. You could also use it as a replacement doorbell.

Circuit diagram
url=projects/282/bigs/canary.gif][/url]

Notes:
This circuit is a modified hartley oscillator with a couple of extra components included. The transformer is a small audio transformer, type LT700. The primary is center tapped with an impedance of 1Kohms at 1KHz . The secondary has an impedance of 8 ohms. The inclusion of R1 and C1 give this oscillator its characteristic "chirp". As the 100u capacitor charges via the 4.7K resistor, R1 the bias for the transistor is cut off. This causes the oscillation to stop, the capacitor discharges through the base emitter circuit of the transistor and oscillations start again. Altering these components alters the frequency of the chirp. The chirp is also voltage dependent. When the push button switch is operated the 100u capacitor is charged. When its released, the oscillation decays and the chirp becomes faster. [

Author:
Email:
Website: http://www.zen22142.zen.co.uk

Similar diagrams

Pulse-Generator & Signal-Tracer

220 Volts Flashing Lamps

LED or Lamp Pulser

Two-wire Lamp Flasher

Electronic Siren

Downed Model Locator

Function Generator

Adjustable High/Low Frequency Sine wave generator

Important!!!
We are not responsible for any injuries or damage caused by information from this website! Working with electricity is dangerous for your life, especially diagrams related to high voltage! We do not guarantee success in building devices using our diagrams! They are not tested by us. For questions about diagrams use author info below diagram or our contact page. Thank you!