RPM Meter Kit (Guarded Fan) – Expansion Version (No Board)
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Prices updated: 13 Oct 2026
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About this product
A learning kit that measures the speed of a 5 V DC fan in RPM using a TCRT5000 reflective sensor. A white mark on one blade passes the sensor once per revolution, and the Arduino counts pulses with an interrupt each second and multiplies by 60. The fan has a closed guard that protects the blades. This expansion version does not include the Arduino board.
Specifications
- Controller
- Arduino Uno
- Fan
- 5 V DC cooling fan, 8x8 cm, guarded
- Sensor
- TCRT5000 reflective sensor
- Fan driver
- NPN transistor (2N2222) with protection diode
- Concepts taught
- Interrupts, RPM calculation, transistor motor driving
- Estimated build time
- 2 hours
Frequently asked questions
How is RPM calculated in this kit?
The Arduino counts sensor pulses during one second using an interrupt. Since there is one mark per revolution, the pulses per second are multiplied by 60 to get revolutions per minute.
Why is a transistor used to drive the fan?
A microcontroller pin cannot supply the current a fan needs, so a transistor switches the fan on and off. The kit also includes a protection diode for the motor.
