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Emergency (Police/Fire) Siren and Chime Electronic Circuits

One circuit (a siren electronic kit) produces sound effects similar to that of a police siren, fire siren, ambulance siren or other emergency siren. The second sound circuit produces a light notification-type chime sound effect.

Screenshot: Emergency (Police/Fire) Siren and Chime Electronic Circuits

SIREN CIRCUIT:
The siren electronic circuit (which makes a fire, ambulance, etc.. siren noise) consists of a mere 20 electronic components (including the battery, switch and power supply). There are a total of 3 transistors used, 2 of which are 2N4403's (PNP), the other being a 2N4401 (NPN). The circuit is great for producing an up-down wail sound effect. Circuit operation theory and potential modifications are discussed.

CHIME CIRCUIT:
The chime circuit produces a sound effect similar to that of the "headlights on" or "keys in ignition" sound that cars emit as a reminder once the driver-side door is opened. The circuit is made up of less than 30 components in total, one of which is a CMOS Inverter IC - a 4069 [PDF].

Please let us know how these circuits worked for you...  
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