Here is an interesting electronic circuit of a powerful bicycle horn based on a popular, low cost telecom ringer chip is described here. This circuit can be powered using the bicycle dynamo supply and does not require batteries, which need to be replaced frequently.
|Circuit diagram of Electronic Bicycle Horn: Click on image to enlarge|
The section of the bicycle horn circuit comprising diodes (D1 and D2) and capacitors (C1 and C2) forms a half-wave voltage doubler circuit. The output of the voltage doubler is fed to capacitor C3 through resistor R1. The maximum DC power supply voltage that can be applied to the input terminals of IC1 is 28V. Therefore zener diode ZD1 is added to the circuit for protection and voltage regulation.
Here we use the tone generator IC KA2411 or FT2411 for producing the horn sound. pin 8 of IC1 is fed to the primary of transformer X1 via capacitor C6. The transformer secondary is connected to the 8 Ohm loudspeaker directly.
- IC KA2411 is also available in COB style, with the same pin configuration.
- The audio transformer used in this bicycle horn project is same as used in transistor radios.