Steam locomotive whistle


Posted on Jan 3, 2013

The waveform of a steam whistle is a complex combination of white noise and an audio frequency oscillation. The noise generator is a transistor (Ql) biased into zener mode. The audio frequency oscillation is a straightforward mixture of two similar (but not identical) sine waves, which after their addition produce a more complex waveshape. The sine wave generators are twin-t oscillators.


Steam locomotive whistle
Click here to download the full size of the above Circuit.

Preset RV1 mixes the two sine waves so that an appropriate waveform is obtained. RV2 mixes this waveform with the white noise. Adjustment of all three presets will result in the required sound. Integrated circuit IC1 is an operational amplifier used as a simple mixer/amplifier which combines the steam whistle, chuffer, (generated elsewhere) and two-tone horn sounds into one, suitable for amplification by an external amplifier.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Amplifier-for-signal-supply
My Arduino In Circuit Programmer
High Performance Sawtooth Generator
Split Power Supply Circuit for Power Amplifier
Interface a HD44780 Character LCD with a PIC Microcontroller
Solar power related schematics
Light circuit diagram: Audio Graphic Equalizer Circuit Using Op Amp
low power led battery voltmeter
Four-Digit Keypad-Operated Switch
Power Power Outages after the call prohibit a re-closure circuit
Automatic recording telephone interface circuit



Top