This project is a wireless frequency from 25-200MHz. The counter has a small coil which picks up the oscillation frequency, and present it on a display with 6 LED.
The heart of this project is the PIC processor. To this processor is 6 LED display connected. The info on the LED is scanned so only one LED is lightning at a time, but your eyes will see it as all LED are lightning at the same time. The author uses a sensitive prescaler which divide the signal with 64. The output of the prescaler is then connected to a counter input of the PIC processor. PIC-processor Imagin you have a 200MHz oscillator. The prescaler picks up the signal and divide it to 200*106 / 64 = 3.125MHz output signal. Inside the PIC at RC0 is a 16 bit counter. This counter is first reset and then it counts during 64mS. If the frequency was 3.125000MHz during 64mS, the counter will reach 200.000 which will be presented to the display. The resolution will be 1kHz which is good enough for a handheld wireless frequency counter. Of course one can make the counting time longer and thereby get more digits, but I seldom need more than 1kHz resolution
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