Build your own speedtrap - click on pictures to entlarge
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Speedtrap sensors.
Other sensors can be use, must be logiclevelswitching. |
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Left - waterlevel Middle - photosensor Right - laser |
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Right two holes to fix sensor on rail |  |
Level for sensor |
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The mirror at the right *shoot* the laser back to the sensor |  |
There is only one meter needed between the sensors. Less is possible, 10 till 100% of one meter [U] |
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Laserlight with the mirror |  |
The two pcb's are mount in sandwitch |
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Two pcb's, one with dispaly and swiches, the onther one with the electronics |  |
Very small pcb |
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Sensor input, use USB-connector |  |
The flatbandcable between the pcb's |
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Display after startup. Buttonfunctions are be able. |
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Display and speedtrap ready to use.
Left, sensor1 - right, sensor2 |
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Schematic |  |
Layout and components |
| HEX-zip | Schema - PDF | ||
| HEX-txt | Layout - PDF |
Operation of the Speed Trap Word Definition
| meter | The light gate spacing you measured in U |
| µs | Time in Microseconds, 1/1 000 000 |
| ms | Time in Miliseconds, 1/1000 |
| meter/s | Speed in meter per second |
| kilometer/h | Speed in (meter*1000) per hour |
Normal Button Operation
| Button | Name | Action | Display |
| 1 | Arm | Enter timer mode | [= =], [Err] (Check inputs) |
| 2 | Previous | Cycle the last 16 latets recorded values | [000], [-E-] (Overflow) |
| 3 | Type select | Select µs, ms, meter/s or Kilometer/h | [ uS], [nnS], [U/S], [U/H] |
| 4 | Lenght | Select gate spacing between sensors | [L01] ... [L10] 10%.......100% (100 % = 1 meter) |
| 5 | Trigger | Select trigger on logic level 0 or 1 | [--|_], [__|-] |
| 6 | Debug | Check sensor input | [0-0] [1-1] |
Push Button During Startup
| Button | Name | Action | Display |
| 1 | Arm set | Default state | CLr |
| 2 | Previous | Clear recorded values | C16 |
| 3 | Type | Select display type CA or CC | 123 |
Default settings
| Name | Value |
| Previous | 000 |
| Type | U/S |
| Lenght | L03 |
| Trigger | __|- |
Display show you mS = nnS and km/H = U/H
Why, we need four displays to show knn/h for km/h and we have only three displays.