In a crowded Large parking lot park , the most disturbing is not quickly found their own car. use of This example describes the car quickly to find device , is able to quickly find the car.

Circuit Work

of the motor vehicle Quick Find circuit from the transmitter and the receiver of two parts, in Figure as shown .

Transmitter circuit by switches Sl, battery GBl, time base IC lCl, resistors Rl, potentiometer RP1, capacitors Cl-C3, inductor Ll and the antenna Wl composition. Receiver circuit from the battery GB2, GB3, switch S2, operational amplifier integrated circuit IC2, resistors R2-R7, potentiometer RP2, light-emitting diode VLl-VL5, capacitors C4, C5, inductor spit and antenna W2 composed of .

By the ICl and RPl, Rl, Cl comprising oscillator circuit generated oscillator signal ( signal frequency below the AM AM band carrier frequency) by C2, Ll , and C3 tuned after the by the antenna Wl launch out . W2 received wireless signal by the C4, L2 , and C5 selected frequency and lC2 magnification ( magnification of 1000 ), the driver VLl-V Island light. Transmitter and receiver closer , the stronger the signal , VLl-VL5 light the number the more . Adjusting RPl and RP2 the resistance can change the circuit receive sensitivity.

Component selection

Rl-R7 selected 1/4W metal film resistor or carbon film resistors . RPl use of small synthetic membrane potentiometer or variable resistor ; RP2 organic, solid potentiometer or variable resistor. Cl used monolithic capacitors or polyester capacitors ; C2 and C5 are selected mica trimmer capacitors ; C3 and C4 are selected high-frequency ceramic capacitors. Ll and L2 are selected TDK color code inductor .

VLI-VL5 are made of f3mm high- brightness light-emitting diode .

ICl selected NE555 type of when the base integrated circuit ; IC2 used µA471 type of op amp IC .

GBl-GB3 are made of 9V laminated battery. Wl and W2 to use the radio whip antenna . S1 and S2 are selected small single pole toggle switch.