Electronic Timer
Digital Timer- science project?
I am currently working on a project for the Science Olympiad competition
I need to create a viechel which will stop after reaching a distance supplied by the judges. Sounds simple right, d=v/t, find the velocity of the car before hand, find the time mathmatically with the given distance and make the car stop in x number of seconds.
the only problem is that any commercially available timers are either too expensive or not accurate enough (baking timers) and need to be rigged to stop an electronic circut running to the motor.
Any information on how to make an electronic timer/ where to buy one that is accurate and cheap enough (<$20) would be greatley appriciated.
The only really reliable method would be counting the revolutions of the drive wheel.
If you can afford a few 4017 ICs, one AND gate, a driver transistor and a small relay, then you can rig the whole thing in such a way that the relay energizes after a given number of revolutions have been counted (distance divided by circumference of the wheel), and its NC contact disrupts the supply to the drive motor.
You need to think of how to deliver the pulse from the wheel / axle to the first stage 4017 (Clock pulse). Some black/white paint and a reflective sensor would be best.
Electric Timer Installation by Mister Landscaper
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