Hall effect ICs are used as proximity sensors for applications such as proximity detection and angular velocity measurement of rotating mechanisms. Hall effect devices can detect mechanical rotation without mechanical contact.
Hall effect ICs detect electrical displacement, adjust signals, and increase hysteresis. Basically, this device measures the electric field generated by a magnetic field along the X direction on a semiconductor. Therefore, if you place the semiconductor in an electric field with sufficient amplitude in the X direction, the Hall effect device can also detect the electric field.
Internal combustion engine design requires a precisely controlled ignition sequence. Microcontrollers that control engine parameters not only have to modify the ignition relationship for the piston position, but also require feedback on various valve timings in more advanced engines. In addition, this novel method is a simple way to measure the ignition timing, which is helpful for diagnostic assistance and engine error-checking hardware. Even the most basic carburetor adjustment on a lawnmower requires a method of measuring the engine's speed per minute. A four-stroke small engine generates a spark every time the engine rotates. Therefore, this spark detection is a direct representation of the engine's speed per minute.
Simply place the Hall-effect IC in the correct direction next to the spark plug line, and you can use its electric field to measure the spark plug pulse. You can use electrical tape to achieve simple isolation between the device and the spark plug wire. Because Hall-effect ICs have internal signal adjustment and hysteresis, the basic frequency can be read from the device without adding components, which is completely different from the traditional current transformer method.
The circuit converts the pulse from the Hall effect into a DC voltage that most ordinary voltmeters can read. The Hall-effect IC provides an open collector output. You only need a pull-up resistor. The sensor converts the generated series of pulses and converts them into voltage using the National Semiconductor's LM2917 frequency-voltage converter. Select C1 and R1, and adjust the output voltage according to the frequency range encountered by the charge pump part of the device. For a four-stroke single-cylinder engine, 5000 r / min is sufficient.
The circuit provides an output voltage of up to 5V and requires a 9V battery supply voltage. The working method is straightforward: pressing the Hall effect IC on the spark plug line, the voltage on the DVM (digital multimeter) can be interpreted as the number of revolutions per minute. Since the measurement is non-intrusive, this method can easily be used for repeatable measurements or for analysis of multi-cylinder engines. The measurement of the car engine is slightly different. The car engine has a mechanical switchboard, which generates a spark every two engine revolutions. An ignition system without a switchboard and an ignition coil per cylinder also generate a spark every two engine revolutions.
Since there is no electrical contact with the ignition system, this circuit itself provides high-voltage insulation capability. Therefore, only the logic level compatibility problem remains with the interface between the microprocessor and the microcontroller. The power supply voltage of the Hall effect IC is 4.5 V to 24V DC, so it can be used for standard 5V processor and car voltage. Multiple sensors can be connected to provide ignition diagnosis and timing analysis for automotive applications.
