Wednesday, August 31, 2011

Accurate LC inductance /Capacitance Meter

About The Project 

This is accurate home made LC inductance/capacitance meter built with very common components which are very easy to find all around . The range of this LC Meter is extremely good at measuring very low value of capacitance and inductance.

LC Meter's Inductance Measurement Ranges:
- 10nH - 1000nH
- 1uH - 1000uH
- 1mH - 100mH

LC Meter's Capacitance Measurement Ranges:
- 0.1pF - 1000pF
- 1nF - 900nF

it auto calibrate when power up , so there is no chances of human error in calibration. we can also re calibrate at any instance of time by pressing the reset button.this meter is completely auto range.


  • No particularly accurate components are required, except for one (or more) accurately known "external" capacitors used to calibrate the meter.
  • The two 1000pF capacitors should be fairly good quality. Polystyrene are preferred. MKT are fine. Greencaps tend to drift in value too much. Avoid ceramic capacitors. Some of these can have high losses (and it is hard to tell).
  • The two 10uF capacitors in the oscillator should be tantalum (for low series resistance/inductance).
  • The 4MHz crystal should be a genuine 4.000MHz one, not something approximate to 4MHz. Every 1% error in crystal frequency adds 2% error to the indicated inductance value.
  • The relay should be a low current one. The PIC can only provide about 30mA of drive current.
  • Don't forget the "catch" diode across the relay coil!

PCB Design

Download the Firmware and schematic


  1. j1 and other jumper j2,j3,j4 grounded same as j1

    used for calibration and debugging

  2. Thancs for sharing.
    This is a very nice project.

  3. i have try this circuit relay was getting on but .. i had a out put is "000000001" . if i disconnect the J1 means "over Range" .. please replay

  4. when you connect the jumper if it show 000000 it means l c oscillator is not oscillating due to some connection fault ,,wrong value or faulty components

    The "Overrange" message is displayed when the oscillator frequency exceeds 655350Hz or falls
    below 2560Hz.

    and the value you saw is telling 00 hz

  5. Hi, Can you plz post source code or send to my mail id Thanks in advance. I tried your serial lcd. It is very useful Thanks for that too......:)... your tutorials are very useful

  6. Hi to all,
    in my case display shows only CALIBRATING and nothing else. What is wrong with my setup? Best regards and many thanks in advance for your kind cooperation

    1. if your prototype stuck on calibrating then please check the firmware

    2. mine is stuck at calibrating too , what to do now?
      kindly explain jumpers j2,j3,j4 connection?

  7. hi my friends...
    I'm from Türkiye.... my name is omer and I need this project a lot....

    but ı couldn't download it.... Who can help me to download......

    And is this project run?
    İf you can know about this project, can you help me...
    Thanks a lot...
    Please contact me with my e-mail.... :

    1. i have checked the download like and it's fine please try again

  8. Hi,

    have you made any circuit that tell me the voltage rating of a capacitor. i have doubt on voltage rating written on a capacitor.

  9. Do you happen to have the source code available? I'd like to see if I can try to adapt it for a PIC16F88, and possibly 7 segment displays... Thanks.

  10. Hi,
    Can you pls give me the original pcb file?, coz i really dont have very much knowledge abt pcb drawing.

  11. Hello Gaurav,

    Post the source code for this please so we can modify/port.


  12. can i replace pic16f628 with pic16f84a?

  13. how can i change hex code to c language coding.... and also want to know that how can i make microchip ic burner so that i can burn ic

    1. sure you can do this is c no problem what so ever.

      here is the link to my another posts whic shows two different programmer .

  14. i tried this project and the lcd just give "orange" and and some blocks then after press cal button it gives
    "0.4 L= calibr" what is the problem

  15. please , send me the exact size of PCB in pdf .....:-

  16. im building a similar project with pic18F242 can I please have the C source code so i can work on it

  17. Thank you for this project, is possible to have the source code, or an explanation on how it works?
    Thank you so much!

  18. I need the program for this project. Only Hex file is given here

  19. I have a problem. " over range " what is problem

  20. Replies
    1. yes it works pretty well , i still have it with me since i made it.

  21. Hello,

    Can you give me the original pcb file?

  22. Hi Gaurav

    I tried to simulate the project in Proteus and the display gets stuck at "Caliberating..". After thorough checking I found that your posted schematic does not match with the actual pinouts of the microcontroller. Please see the your schematic below with indicated correct ports. Kindly verify if the port numbers are correct or the pin numbers?

  23. Hi Sir,dy done the inter
    I am also doing the same project currently for my final sem.I have already done the LCD interfacing with PIC microcontroller. But i am unable to do the calculation part in the program. Can you please provide me the source code or .c file?
    my mail id is: