Frequency Meter with 40 MHz Measurement

Figure 1 

The device is a simple, small, and cheap frequency meter with out any hard to find components to be able to measure frequencies up to 40 MHz while having below 1% errors.

Most of the analog and digital circuits can be debugged by the 1% degree of precision which will give more of the ability to analyze several aspects that are hard to find. There are only 3 components and 8 resistors used to build this frequency meter on a veroboard which can be plugged-in to any standard breadboard. An ATmega16 microcontroller is used for the design of the circuit. Although there are no crystal oscillators, the internal RC oscillator was used with a calibration of 8 MHz.

The frequency is measured using a probe that is connected to W1 terminal. The frequency is fed to the Pin PB0 and the clock input of the 4-bit counter 74191. The measured frequency will be divided by 16 using the 4-bit counter before feeding it to the microcontroller.

4 cells integrated into one package are used for the 7-segment display common anode mode, which reduces the number of wires for enabling the different cells.

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