I am building a speed detection system using laser gates but I need a schematic designed for me that will show me how to build this and what chips and other electronic devices I will need. I did find an existing design online which I am basically going to copy except I need some modifications made to this design. Here is a link to the design I found.....
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HOWEVER....I do not want to display / record the time.... I want to display Miles Per Hour (mph). So, for the schematic that is shown in the above mentioned link, I would like an extremely accurate timing circuit instead of the stopwatch he uses in his design. I believe a crystal oscillator will be required for this but I am open to your suggestions. I would like this device to be extremely accurate so I am assuming the timing circuit will need the ability to time in 1/1000th of seconds. I need this circuit to calculate the mph based off the time recorded and distance between "Point A" and "Point B". Here is my explanation in simpler terms....
1. I want a laser and photo-sensor at "Point A". When an object passes through this laser beam, it should start the timer.
2. I want a laser and photo-sensor one inch away from "Point A" which I will call "Point B". When the object passes through "Point B" it needs to stop the timer.
3. I then need this circuit to take the time recorded for the object to pass from "Point A" to "Point B" and calculate the MPH. I would like the MPH reading to display on a 3 digit LED number display.
The max speed of objects passing through the beams will be no faster then 150mph. I would like the MPH reading to remain displayed on the LED display until another object passes through "Point A" & "Point B"....at which time the new MPH reading will show up on the display. I would like this to be a battery operated circuit. Please give me your quote for the DESIGN schematic only. I do not need you to physically build this circuit. I can build it and test it myself.