555--Automotive device circuit diagram

Car Audio Crystal 3.2*2.5mm 3225 24M (24.000MHZ) 20PF 10PPM 20PPM 30PPM

Tantalum capacitor TR3C107K010C0100 original 2011+

ESD TVS electrostatic protection tube 0201 package 3.3V ultra low capacitance ESD

inductance

SMD aluminum electrolytic capacitor

As shown in the figure, the car search device includes a transmitter and a receiver. The transmitter uses 555 as the core to form a medium-wave frequency oscillator. The oscillator frequency should be chosen to be slightly lower than the carrier frequency of the broadcast amplitude modulation 535KH _{Z. The} frequency value is determined by R ₁ , RP ₁ and C ₁ , that is, f=1.44/( RP ₁ +2R ₁ )C ₁ , L ₁ , C ₂ form an output resonant tank, which is selected and then transmitted through the antenna through C3. The receiving circuit consists of an input frequency selective network and a 741 operational amplifier. The amplification factor of the amplifier depends on the ratio of RP ₂ /R ₂ . LED ₁ ~ LED _{5 is} used to indicate the strength of the received signal, as the signal is strengthened, the LED will be illuminated sequentially! !