afx slot car lap counter

Posted on Feb 6, 2014

AFX slot car sets are very enjoyable but you can increase the fun with a lap counter. This circuit will count from 00 to 99, with independent counters for each track. The sensing device used is a Hall effect sensor (UGN3503; available from Dick Smith Electronics). One of these sensors is glued under a section of each track (printed side up); betwe

afx slot car lap counter
Click here to download the full size of the above Circuit.

en the slot and one of the track rails is the best spot. In this position, it will allow the ground effects magnets on the cars to pass over them. The sensor will provide a voltage of about 3V when a car passes over it and about 2V without a magnetic field. Both counter circuits are identical, with dual op amp IC5 handling the signals from both sensors. IC5a and IC5b are wired as comparators, with a 2. 5V reference derived from zener diode ZD1 via the 10kO and 12kO resistors. Each time the output of IC5a goes high it clocks IC1a, a 4518 BCD counter. NAND gates IC2a & IC2b provide a carry out to the other half of IC1 for a 2-digit display. More counters may be cascaded this way to provide extra digits. The BCD outputs of IC1 drive 7-segment decoders IC3 & IC4 which drive common cathode LED displays. Push-button S1 resets the counters to 00 for both tracks for the start of a new race.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Strobo triggering schematics
    Guitar OmniDrive effect
    Car auto-dimmer
    5V Power Supply For On Train Radio Camera
    PIC 16F88 Digital Thermometer Light Meter and resistance ohm meter
    PCB Parametric Audio Equalizer
    Connecting Infrared Thermometer MLX90614
    Boost Switching Converter Design Equations
    Arduino Based Current Sensor Circuit
    Vladimir Utkins Free-Energy Secrets
    1997 Buick Century the headlight relay
    Low-noise preamplifier circuit
    Bonsai electronic circuit