larva said:
Need a circuit for counter the laps.
This is going to be a complex design, so let's start with the requirements. You want a hardware circuit to count your slot car laps. Here are some questions for you to please answer:
- do you also want to measure the time for each lap?
- we will assume that you will use 5 volts power supply, is this OK?
- you will need a start button and a reset button.
- how will the lap counting finish? Is there a fixed number of laps, or a fixed duration for the race?
- how will you signal the drivers when the race starts?
- will you have enough for 4 cars, or only 2 cars, or some other number?
- you will need a false count timout (allows no counts to occur for fixed number of seconds after the last count). Do you want this to be adjustable?
With all these kinds of features, it is no wonder that using an old PC like a 386 machine is easier than building a hardware circuit to do this job. You could also use a PIC or AVR processor chip, which might make it easier to add features.
I would assume that the car interface is a light detector (looks like an LED) embedded in the bottom of each slot near the start/finish line. This is what we use and it works quite well. This approach requires that a bright incandescent lamp be mounted above the track facing down to the start finish line. When the car crosses the start/finish line, it breaks the light reaching the detector and gives you a pulse which is then fed to your counter.