The Opamp (is used only as a Schmitt Trigger) can be any part that works above 5Mhz .... I have an updated design using a schmitt trigger (74HC14)... it will be easier and much cheaper than the opamp version i guess...
As for the Capacitor values it should be 15pF .... (but its a non critical as specified in the datasheet of pic16f72). I didnt use it in my hardware circuit and it just worked well...
The Display is a JHD162A (16x2 Character LCD) actually any HD44780 based Char LCD must work.
The updated schemetic file is at....
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---------- Post added at 16:22 ---------- Previous post was at 16:09 ----------
if you use an opamp its OPA2322. (BURRBROWN costs around Rs 200
) ....
So, better option would be to use a 74HC14 which is a Hex(has 6 inverter modules) Inverting Schmitt Trigger... It would be well around Rs 20 to 30... within our budget i guess ...
The model has been simulated in Labview Proteus and has been also been implemented in hardware...
Labview Proteus shows an error in reading of 2% (such errors are pointless in real life..) Still im trying on a new averaging feature which would reduce the errors, Would be uploading the code if successful (also planning to add a LC meter function to the same circuit ).
The Coding is done to perform the job and does no fancy stuff like showing the readings in Mhz / KHz , decimal points etc...
It simply shows the reading in Hz...