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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 supports only 2x16 LCD display, and you have to adapt code if you want to use 1x16 or 4x16 row display. For example if you use 1x16 LCD as I did, display doesn't print all 16 chars in 1 row.... First 8 caracter goes to row 1 (Lcd_Chr(1,6, ch+48);), but for caracters 9-16 you have to print on the second row (Lcd_Chr(2,1, ch+48);). 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. |  |
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| Measuring 2,2uH factory made coil. | Measuring 2,7pF capacitor. |
