Category: Main page » Measured

Digital Radar Speedometer

Author: Serge Saati

Radar Speedometer


This circuit is a Digital Radar Speedometer. It allows us to evaluate the speed of any object moving, especially cars and other vehicles. The speed is calculated in kilometers per hour (KPH). Its display has three digits. This radar works with the laser reflexion. It sends laser radiation to the object and this object reflects the laser radiation to the radar. To evaluate the speed of a vehicle, we must be in front of it. In other words, the vehicle must come in our direction. The front of the radar must point the front of the vehicle. The radar has the shape of a pistol. In this radar, it has a laser LED and a laser diode. Both have a lens.

The laser LED can send a spot of light to a distance of 90 m (295 ft). It's very important that the distance range of the laser LED is 90 m, if not, the speed will not be calculated properly. The laser diode, which receives the light signal by the laser LED, must be able to detect the light which is same color as that emitted by the laser LED. The laser diode and the laser LED must be placed one beside the other. They are protected by a tinted pane. They must be placed at the front of the radar and point the outside. The radar is powered by a 9V battery and it has a SPST switch to control its power state.

The display, or the speed indicator, is placed at the rear of the radar, just on the right of the overload LED indicator. All the logic components of the circuit must be of the 74AS series and TTL type. Because they have short time of response (less than 1.7 ns) and have high frequency supports (more than 200 MHz). The radar can evaluate the speed of an object moving between 0 to 999 km/h. After this speed, the overload LED indicator will turn on and the "999" will still displayed. The radar displays the speed during 3 seconds, after this time, it displays "zero" (0).

Emilio 2016-10-18 15:11:18
Very useful circuit!

Can I use this for experimental rocket telemetry?

Please say me what kind of laser parts has used?

Thanks a lot.

[Reply] [Reply with quote]
↑ +13 ↓
oral smith 2015-08-23 20:15:53
Good day,

I like your circuit very much, I will like to Build something like it for my school project. Could you please provide some specifics like part number used for the laser. I am doing a demo from kids at my school and want it to work without any problem.

Thank you verymuch

[Reply] [Reply with quote]
↑ +19 ↓
Willem Woef 2011-06-03 10:39:43
Interesting circuit!
Would you please provide some typenumber of suitable transmitter and receiver lasers?
Thanks in advance...

[Reply] [Reply with quote]
↑ +39 ↓

Pages: [1]

Leave a comment

Your name:
Your Email:

Type the characters: *