DIY Electronic Hit Indicator

A DIY electronic hit indicator for steel targets using an MPU6050 accelerometer, XIAO RP2040, MOSFET-switched LED row, and 3×AA battery power.

The main enclosure mounts behind the steel gong while a narrow vertical LED face sticks out from the side so the flash can be seen.

Features

• MPU6050-based hit detection
• Adjustable sensitivity using a WH148 B10K potentiometer
• MOSFET-switched LED output
• 3×AA battery powered
• Adjustable LED flash duration
• Adjustable flash speed
• Designed for a 3D printed enclosure
• Narrow LED face reduces chance of being hit
• Main body hidden behind steel gong
• Breadboard-testable before soldering

Main Components

• Seeed Studio XIAO RP2040
• MPU6050 accelerometer module
• IRLZ44N / IRLZ44NPBF logic-level MOSFET
• 10× 5mm high-brightness LEDs
• WH148 B10K potentiometer
• 3×AA battery holder with switch
• 40x60mm Perfboard
• 3D printed enclosure

How It Works

1. The MPU6050 senses vibration from a target impact.
2. The XIAO RP2040 reads the acceleration spike.
3. If the spike exceeds the sensitivity threshold, D2 turns on.
4. D2 drives the MOSFET gate.
5. The MOSFET switches the LED ground path.
6. The LED row flashes for the programmed duration.

Power

The project is powered by a 3×AA battery holder.

Battery positive powers:

• XIAO 5V / VBUS
• LED resistor power rail

Battery negative connects to:

• XIAO GND
• MOSFET source
• MPU6050 GND
• potentiometer GND

Do NOT connect the battery pack directly to the XIAO 3.3V pin.

Potentiometer

This build uses a standard WH148 B10K 10k potentiometer.

Recommended sensitivity range:

float minThreshold = 0.4;
float maxThreshold = 1.5;