Ένα μέρος της κριτικής έχει μεταφραστεί αυτόματα.
Frequency measurement: I managed to run it only if the input signal is between 4.7 and 5 volts (not to be exceeded). The signal goes directly to pin 3 of the PIC (5V max). An incoming signal amplification circuit must be provided. Quartz measurements: Very poor circuit. It depends a lot on the supply voltage, the temperature and the quartz frequency. Limited use. Measurement examples: (3,2748 MHz -> 0) (4,9152 MHz -> 4,9166) (16 MHz -> 16,001 16,006) (20 MHz -> 20,007) (22 MHz -> 22,007). Strange situation: if the power is about 9 volts, the 4.9152 MHz quartz give these results: -> 14,667 14,669 14,672 14,681 Third harmonica?) Under investigation.
This came with no instructions, but the PCB is labelled with component values so I found it very easy to assemble. A description of how to use the add/subtract functions can be found at http://www.qsl.net/dl4yhf/freq_counter/freq_counter.html (as mentioned by tom_pin in the product discussion). The display is much easier to read if you add a red filter. If I had the chance to make 1 change, I'd provide space on the PCB for 4mm sockets for ground and frequency signal in; then it would be easy to connect different sorts of test lead (e.g. pointy or spring hook).