555 automobile device circuit diagram

As shown in the figure is the circuit diagram of the 555 car finding device , including the transmitter and receiver. The transmitter uses 555 as the core to form an oscillator with a medium wave frequency. The oscillation frequency should be slightly lower than the carrier frequency 535kHz of broadcast AM. The frequency value is determined by R1, RP1, and C1, that is, f=1.44/(RP1+2R1)C1 , L1 and C2 form an output resonant circuit, perform frequency selection, and then transmit it through the antenna through C3. The receiving circuit consists of an input frequency selection network and a 741 operational amplifier. The amplification factor of the amplifier depends on the ratio of RP2/R2. LED1~LED5 are used to indicate the intensity of the received signal. With the signal and intensity, the luminous tubes will light up sequentially.

ck="window.open(this.src)" alt="Click to see larger image"/>