Not exactly something I made, but I just acquired a K-band (24.15 GHz) Doppler Radar, just in case someone wants to see how accurate their speedometer is, or wants to clock their drone or find out how fast they can throw a baseball.
Can you think of any other uses for it, conventional or otherwise?
Next up…design and mill some tuning forks for it. For a 65 MPH fork, I’ll need to make one that rings at 4682 Hz. Anyone know where I can get some flat bar aluminum stock, about 3/16 thick and maybe 2 by 5 inches?
We should look at its output waveform, then see what happens when we send similar signals at various frequencies at it…
Ya know… for science.
You also could set up a speed trap with a raspberry pi and camera that identifies patrol cars and checks their speeds.
Hard drive platters make excellent tuning forks. Much better than aluminum alloy.
I used to have some patterns for making specific frequencies ( musical tones, for wind chimes), no idea where I found them. Trial and error should get close enough so even if you couldn’t get exactly 40MPH you could label each one for what it should produce.
Whatever it rings at, divide by 72.03 to get MPH.
It would be fun…but many departments have since gone exclusively LIDAR.