AFX Slot Car Lap Counter(UGN3503)

This article briefly describes the AFX Slot Car Lap Counter (UGN3503). This principle is easy to understand, but also very practical. Depth understanding of circuit elements, you can better grasp this principle. In this circuit, you can learn about and purchase these components: UGN3503.

AFXslot 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); between 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.

Figure 1 AFXSlot Car Lap Counter Circuit Diagram

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 4518BCDcounter.NANDgates 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. TheBCDoutputs of IC1 drive 7-segment decoders IC3 & IC4 which drive common cathodeLEDdisplays. Push-button S1 resets the counters to 00 for both tracks for the start of a new race.

Author: Placid Talia – Copyright: Silicon Chip Electronics

 

 

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