piclist 1998\10\07\035205a >
Thread: 4 digit auto-ranging frequency-meter.
www.piclist.com/techref/index.htm?key=digit+auto+ranging
picon face BY : Peter Gee email (remove spam text)



What would happen in the schematic shown if the input voltage when negative
with respect to the gnd of the PIC ?
my guess is that it wouldnt be good for the PIC.
in a similar project ( from memory), they use a coil, capacitor, signal
diodes, and a transistor to filter and switch the incoming frequency to make
it nicer for the PIC to count.
i built the project, and it seemed to give accurate results in comparison to
a bench frequency counter at a frequency of 40Mhz using a 10Mhz 16cf84.  (i
used an fm RC transmitter to calibrate it) -- i don't have a frequency
generator higher than that so i can't test its high end response.
regards


Pete

<003301bdf1c7$14c3bcc0$3737d983@novarossi_chem.chem.utas.edu.au> 7bit

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