DIY SPEED GUN
Hardware- 2 Devlogs
- 6 Total hours
I am making a device that will measure the speed of moving objects from a distance.
Devlog – Day 2
Date: August 14, 2026
Time Worked: 2 hours
Today I finalized the circuit diagram for my DIY radar speed gun and continued working on the physical enclosure design.
While reviewing the electronics, I discovered that the LM386 amplifier I originally planned to use was not suitable for conditioning the CDM324’s Doppler signal for the ESP32. I researched alternatives, including the MAX9814, but ultimately decided to use an LM358 op-amp breakout board because it provides a dedicated input and can be configured to amplify the signal at 3.3V.
I then completed the full circuit diagram, including the battery, power switch, CDM324 radar sensor, LM358 amplifier, ESP32, and OLED display. I also started designing the main enclosure and planning how the horn antenna, sensor, electronics, and display will fit together in the handheld housing.
Next Steps
- Continue designing the main enclosure.
- Finalize the component placement.
- Review the wiring.
Devlog – Day 1
Date: August 13, 2026
Time Worked: 3 hours 30 minutes
Today I started working on my DIY radar speed gun project. I researched different microwave Doppler sensors and selected the CDM324 24GHz sensor because of its better resolution and ability to detect smaller and faster-moving objects.
I also planned the complete signal-processing system, from filtering and amplifying the sensor’s Doppler signal to processing it with an ESP32 and displaying the calculated speed on an SSD1306 OLED.
I sourced the main components and designed a custom two-stage conical horn antenna in CAD to improve the sensor’s directionality and range. I also researched how horn antenna size affects gain, which helped me set more realistic expectations for the additional detection range.
Next Steps
- Design the main body of the radar speed gun.
- Continue developing the wiring diagram.
- Plan the placement of the electronics inside the enclosure.
