AN-663: Sound Effects for the COP800 Family:  National Semiconductor Application Note   (app note added 2/06)

Automatic School Bell:  Circuit / schematic (added 02/05)

Canary Sound Effect:  Reverse engineered circuit diagram of a commercial Electronic Bird. This one was built into a plastic christmas ornament and runs off a 9V battery. Note that L1 is actually just an audio transformer with an unused secondary winding.  (added 10/04)

Cuckoo sound Generator:  Agreeable, very close sound imitation Suitable for sound effects, door-bells etc. (added 9/04)

Dog Whistle:  (electronic Circuit diagram added 03/03)

Electric Canary:  (circuit added 11/06)

Electronic Canary (Doorbell):  This circuit is a modified "Hartley Oscillator" with a couple extra parts.  T1, the LT700 (or equivalent, is a small center tapped (ct) audio transformer with an impedance of 1000 ohms at 1000 hertz.  The secondary of this transformer has an impedance of 8 ohms.  Usually noted as 1K:8 ct.  I tried a couple other models like the red and green types (taken out of a $5 made-in-china am pocket radio) and they both work good.  You may have to adjust the caps to get the sound... (added 2/06)

Electronic Canary Sound Effect:  Reverse engineered circuit diagram of a commercial Electronic Bird. This one was built into a plastic christmas ornament and runs off a 9V battery. Note that L1 is actually just an audio transformer with an unused secondary winding.  (added 2/05)

Happy Birthday Singer solar engine:  Time-Controlled Solar Engine: The original Type 2 Solar Engine was based around the "Happy Birthday Singer" (HBS) chip that was pulled from the original Hallmark singing greeting cards. .   (added 6/06)

Model Train Diesel and Horn Sound Module:  (electronic (schematic / circuit added 4/02)

Noisemaking Circuits:  police siren (added 8/03)

Rain sound effect Generator:  Agreeable, relaxing effect, helping to fall asleep Small portable unit, 3V battery powered (added 3/05)

Sound Effects for the COP800 Family:  National Semiconductor Application Note   (app note added 2/06)

Sound Effects Generator #1:  (electronic (schematic / circuit added 4/02)

Sound Effects Generator #2:  (electronic (schematic / circuit added 4/02)

Two-Tone Trainhorn:  (circuit added 9/04)