1. Introduction
This manual provides detailed instructions for the installation, operation, and maintenance of your DIGITEN 4-Digit Green LED Tachometer RPM Speed Meter. This device is designed to measure rotational speed (RPM) using a Hall proximity switch and magnet sensor, suitable for applications such as lathes, CNC machines, and conveyor belts.
2. Package Contents
- Tachometer x 1
- Hall NPN proximity sensor x 1
- Magnet x 1
Image: Contents of the DIGITEN Tachometer package, including the display unit, Hall sensor, and magnet.
3. Specifications
| Power Requirement | DC 8-15V |
| Measure Range | 5-9999 RPM |
| Clear Zero | Automatic (approx. 10s, longer for higher RPM) |
| Refresh Frequency | 0.2-0.5S@120-1200RPM; 0.25-0.06S@2400-9999RPM |
| Measure Accuracy | RPM < 5000, ±2; RPM > 5000, ±3 |
| Display | Green 0.56 inch LED |
| Signal Type | Pulse signal, Hall NPN 3 wires normally closed |
| Hall Proximity Model | NJK-5002D |
| Sensor Appearance | M12mm cylinder |
| Detection Range | 2-3mm |
| Proximity Output Current | 200mA |
| Detected Objects | Magnet |
| Response Frequency | 100HZ |
| Tachometer Dimension | 72x36x20mm |
| Panel Cutout Dimension | 68x33mm |
| Sensor Dimension | M12x37mm |
| Operating Temperature | 0 to 50°C |
Image: Detailed dimensions of the tachometer display unit, showing length (72mm) and height (36mm).
4. Setup and Installation
4.1 Mounting the Tachometer Display
The tachometer display unit requires a panel cutout for flush mounting. Ensure the cutout dimensions match the specified 68x33mm. Secure the display unit into the panel.
4.2 Mounting the Hall Proximity Sensor and Magnet
- Mount the Hall NPN proximity sensor in a fixed position near the rotating part (e.g., shaft, pulley) whose RPM is to be measured.
- Attach the magnet to the rotating part. Ensure the magnet is securely fixed to prevent detachment during operation.
- Position the sensor so that the magnet passes within its detection range of 2-3mm (0.07"-0.12") during rotation.
- Verify the magnet's orientation. The direction of the magnet relative to the sensor is crucial for proper detection. If the tachometer does not register RPM, try flipping the magnet's orientation.
Image: The Hall proximity sensor, showing its M12mm cylindrical form factor and the attached cable.
5. Wiring Diagram
Carefully follow the wiring instructions below to connect the tachometer display to the Hall sensor and power supply. Incorrect wiring can damage the device.
5.1 Hall NPN Proximity Sensor Wiring
- Brown wire: Connect to Power + (DC positive)
- Blue wire: Connect to Power - (DC negative / Ground)
- Black wire: Connect to Signal output
5.2 Tachometer Display Wiring
- Red wire: Connect to DC + (Power positive, 8-15V DC)
- Black wire: Connect to GND (Ground / Power negative)
- Yellow wire: Connect to IN+ (Signal input from the sensor's black wire)
Ensure all connections are secure and correctly matched before applying power.
Image: Detailed wiring diagram showing connections between the tachometer display, Hall sensor, and DC power source.
6. Operation
Once the tachometer is correctly installed and wired, apply DC power (8-15V). The green LED display will illuminate. As the magnet attached to the rotating part passes the Hall sensor, the tachometer will detect the pulses and display the corresponding RPM value.
- The display will automatically clear to zero after approximately 10 seconds if no pulses are detected. For higher RPM values, the clear zero time may be slightly longer.
- The refresh frequency of the display varies with RPM, providing a responsive reading across the measurement range.
7. Troubleshooting and Tips
- No RPM Reading or Incorrect Reading:
- Confirm all wires are connected correctly according to the wiring diagram.
- Check the direction of the magnet. If the reading is incorrect or absent, try flipping the magnet.
- Ensure the distance between the magnet and the sensor is within the optimal range of 2-3mm (0.07"-0.12").
- Verify the power supply voltage is within the specified DC 8-15V range.
- Display Not Illuminating:
- Check power connections to the tachometer display (Red to DC+, Black to GND).
- Ensure the power supply is functioning correctly.
- Intermittent Readings:
- Re-check the sensor-to-magnet distance. Vibrations or misalignment can cause inconsistent readings.
- Ensure the magnet is securely attached and not moving relative to the rotating part.
8. Warranty and Support
DIGITEN provides a one-year warranty term for any product issues. If you encounter any problems or have questions regarding your tachometer, please contact DIGITEN customer support. Refer to the product packaging or purchase documentation for contact details.