This is a frequency meter based on PIC microcontroller, with crystal oscillator measurement function and programmable plus and minus frequency settings, five-digit digital tube display, convenient and intuitive, all use direct plug-in components, simple circuit, easy to make. The measurable frequency range is 1 Hz-50 MHz; The oscillation frequency of most commonly used crystal oscillators can be measured; Five-digit precision resolution (for example, 0.0050 kHz, 4.5765 MHz, 11.059 MHz); Automatic range conversion, no manual switching required; Programmable plus and minus frequency settings, used to measure radio transceivers and other equipment; Power saving mode can be , and the display will be automatically turned off if the frequency does not change significantly within 15 seconds; It can be powered by a universal USB 5V interface, or an external DC power supply or 9V battery. The number of components is small, all direct plug-in components, and installation and debugging are simple. The 32.768KHZ crystal oscillator cannot be measured. Due to limited conditions, only the 4-20MHZ crystal oscillators can be measured. The 48MHZ crystal oscillator can also be measured, but because this crystal oscillator uses 3 times the harmonic frequency, the 48MHZ crystal oscillator measurement will display the fundamental frequency of 16MHZ. You can also directly input the frequency signal between IN and G (ground) for measurement. Note that the measured signal amplitude should not be higher than 5V to avoid damaging the IC. Tips: The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use The parts are shipped separately, and welding and debugging need to be completed by yourself Colour:Photo Color Material:PCB Package Contents: 1 x Frequency Counter Meter DIY Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.