Here is a simple project “Car Reverse Horn”, can be used in car as reverse horn i.e. produce sound when car is moving in reverse direction.

Circuit description

The heart of car reverse horn circuit is melody generator IC CIC2877 (IC₁) followed by amplifier IC and few passive components. IC₁ is made from a ROM oscillator and a pre-amplifier which further generate sound. The generated sound output is available at pin 3 which is further connected to pin 2 of amplifier IC through variable resistor VR₁. IC₂ amplify the generated sound up to desired level and its output from pin 7 and 12 is given to loudspeaker through coupling capacitors C₈ and C₉ respectively. The power supply ig given to the circuit from battery of car.

PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)

R₁ = 1.5 KΩ

R₂ = 1 KΩ

R₃ = 120 KΩ

R₄, R₅ = 1 Ω

Capacitors

C₁ = 10 µF/25V (electrolytic)

C₂ = 1 µF/25V (electrolytic)

C₃ = 100 µF/25V (electrolytic)

C₄ = 0.01 µF (Ceramic Disc)

C₅, C₆, C₇ = 47 µF/25V (electrolytic)

C₈, C₉ = 470 µF/25V (electrolytic)

C₁₀, C₁₁ = 0.1 µF (Ceramic Disc)

Semiconductors

IC₁ = CTC2877 (Melody Generator)

IC₂ = AN7148 (Amplifier IC)

Miscellaneous

LS₁ = 8 Ω loudspeaker