LC METER
Free for educational and noncommercial use ! ! !
For commercial use you must contact the author ! ! !
DESCRIPTION:   Basicaly LC meter is frequency meter, just with added LC oscilator that oscilates with measured L or C and result is being calculated. Frequency meter is same as the one published on my web page only with one difference, microcontroller is PIC16F628. It is precise even up to 1 Hz. For more details of measuring frequency see Frequency Meter.
Note that I'm using reed relay with internal damper diode! ! ! If you use other relay without diode, you could damage microcontroller... So place one inverse to the coil...
PRINCIPLE of measuring:    At begining device is calibrated, that means the shaded formulas are not being calculated. Instead, F1 & F2 are measured (F2 with Reed Relay ON). After that are calculated actual capacity Cc and inductance Lc. So don't worry about tolerance of C5 and L1... (they are calculated ! ! ! ). You only have to tune C3 & C4 to 1015pF. And at the end is calulated Cx or Lx where Fx is actual frequency when measuring.
SOFTWARE for PIC16F628:     Program code is written using MikroC. Real challenge was this part, because it had to fit into 2KB of program memory. So don't worry if you find some strange things here, it's that way because MikroC has some bugs. I've reported that to Mikroelektronika, but I gues it went to deaf ears because they didn't even reply... MikroC v8.2 has bug for example when you use custom config for LCD display it doesn't print all 16 chars in 1 row.... But I've found a way out... and it is working just right ! ! ! Also I don't use theirs command Lcd_Out because code is huge so I had to write my own routine for that too.
Links to some usefull web sites.
AllPIC Programmer                                         MikroC
Measuring 2,2uH factory made coil.
Measuring 2,7pFcapacitor.
Donations are appreciated.
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