This thesis presents the design and development of an electronic tachometer for a moped. The main objective was to develop a tachometer that does not require additional external sensors or major modifications to the engine for measuring rotational speed and that can operate with different power supply systems. The signal from the electronic ignition system is used to determine the engine speed. Since its waveform and amplitude are not suitable for direct connection to a microcontroller, the signal is conditioned using a Schmitt trigger, which converts it into digital pulses. An ESP32-S3 microcontroller measures the time interval between consecutive pulses, determines the corresponding frequency, and consequently calculates the engine speed. The calculated value is displayed by an analog pointer driven by a Switec X15.589 stepper motor. The system also includes RGB LEDs for illuminating the tachometer scale and a switching power supply for powering the electronic components.
As part of the thesis, the electronic circuit, software, and mechanical components of the tachometer were developed. Testing showed that the individual parts of the system operate correctly; however, occasional interference occurs when the complete system is in operation. The main challenges are electromagnetic interference generated by the ignition system and the sensitivity of the input circuit. Nevertheless, the developed tachometer is functional, with an average deviation of 24 RPM compared with reference measurements obtained using an oscilloscope and a maximum absolute deviation of 60 RPM. The test results indicate opportunities for further improvements, particularly in the areas of input signal conditioning and the electromagnetic compatibility of the circuit.
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