1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

PIC based high-resolution cap meter

Discussion in 'Microcontrollers' started by Mr RB, Jun 27, 2011.

  1. picbits

    picbits Well-Known Member

    Joined:
    Jan 29, 2007
    Messages:
    2,007
    Likes:
    95
    Location:
    Northants, United Kingdom
    Have you tried sending him a private message on here ?
     
  2. Neimocol

    Neimocol New Member

    Joined:
    Dec 7, 2013
    Messages:
    8
    Likes:
    1
    Thanks by your reply.

    I couldn't find a way to send a private message. The closest thing I've seen is "Start a conversation" but I think this is not the way.

    I am a new member into the forum and I dont know well the operational.

    I'm sorry
     
    Last edited: Dec 21, 2013
  3. picbits

    picbits Well-Known Member

    Joined:
    Jan 29, 2007
    Messages:
    2,007
    Likes:
    95
    Location:
    Northants, United Kingdom
    Yes - the start conversation has taken over from Private Message.

    MrRB hasn't been on for a while though so you may not get a fast reply.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Neimocol

    Neimocol New Member

    Joined:
    Dec 7, 2013
    Messages:
    8
    Likes:
    1

    Thank You very much, Picbits. I could see his last post was some months ago.

    Thanks by information.
     
  6. jjw

    jjw Member

    Joined:
    Apr 16, 2012
    Messages:
    270
    Likes:
    15
    Location:
    Helsinki, Finland
    His email can be found in his page in the Hippyware Licence, where "10$" is the link.
     
  7. Neimocol

    Neimocol New Member

    Joined:
    Dec 7, 2013
    Messages:
    8
    Likes:
    1
    Ohh, YES!! I could see it where you say.
    Thank you very much and Merry Christmas to all of you!!

    Regards
     
    • Like Like x 1
  8. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    i have drawn the schematic on PROTEUS version 7.7............and i have also inserted the latest .hex file in the PIC controller.when i run the programe, the display shows ERROR / LARGE CAP although i have used only 1pf or 10 pf to measure.............. can please help me with the problem.. i have checked the drawing thoroughly..... can not find the problem......it will be very helpful for me if you give me answer
     
  9. JimB

    JimB Super Moderator Most Helpful Member

    Joined:
    Sep 11, 2004
    Messages:
    6,390
    Likes:
    592
    Location:
    Peterhead, Scotland
    ONLINE
    If I understand you correctly, you are using a simulation of some sort to test the capacitance meter software.

    My first thoughts are that the simulator does not accurately replicate the software/hardware.

    JimB
     
    • Like Like x 1
  10. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    yes you are right. before building it on breadboard/pcb, i used the simulation software to see the result. Unfortunately it always showed ERROR. I will try building it on breadboard tomorrow. I know this project works because lots of people have had success. So, you think i should try to build it on breadboard and see the results?

    and thank you very much for your prompt reply. I will need further assistance on this topic.
     
  11. JimB

    JimB Super Moderator Most Helpful Member

    Joined:
    Sep 11, 2004
    Messages:
    6,390
    Likes:
    592
    Location:
    Peterhead, Scotland
    ONLINE
    Yes!
    Simulators are all well and good, but unless you spend LOTS of money on them, they cannot simulate everything.

    JimB
     
    • Thanks Thanks x 1
  12. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    today i tried the project on breadboard but the lcd display still shows LARGE CAP. i have also tried using 470 ohm pull up resistor to fix the problem on breadboard but the result is still showing large cap.

    after debugging i found that there is no oscillation at the comparator output............can you suggest anything to fix this.thanks in advance.
     
  13. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    please any suggestions i tried this project on breadboard..........but still showing Large CAP.......i think my RC oscillator is not working......what can i do?...
     
  14. JimB

    JimB Super Moderator Most Helpful Member

    Joined:
    Sep 11, 2004
    Messages:
    6,390
    Likes:
    592
    Location:
    Peterhead, Scotland
    ONLINE
    I have had a look at Roman Blacks website where this project is fully described and it looks as though the RC oscillator is not running, as you have suggested.
    Why the oscillator is not running is a bit difficult to say.
    Is the PIC you are using new, or has it been used before? Maybe the comparator has been damaged.
    Another possibility is that the 16Mhz clock crystal is not running correctly.
    If it was running very slowly, it would not measure the RC oscillator frequency correctly. However it is obviously doing something becuse you have text displayed on the LCD.
    Apart form that, I have no ideas.

    JimB
     
    • Like Like x 1
  15. NorthGuy

    NorthGuy Well-Known Member

    Joined:
    Sep 8, 2013
    Messages:
    1,218
    Likes:
    206
    Location:
    Northern Canada
    Another possibility is that + and - op amp inputs are connected in reverse.
     
    • Like Like x 1
  16. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    thank you all. for this project i have bought all new equipments and have also checked the connections thoroughly. but i will check again.i just wanted to know whether i need to add any other resistors or caps that is not in the original schematic. i will try again building it....thank you all for your reply i will let you know how the project goes
     
  17. jjw

    jjw Member

    Joined:
    Apr 16, 2012
    Messages:
    270
    Likes:
    15
    Location:
    Helsinki, Finland
    Do you have the 270pF cap at the measuring input?
     
  18. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    yes i did have that cap.i tried the circuit again but did not work.i am still working on it.....:(
     
  19. Neimocol

    Neimocol New Member

    Joined:
    Dec 7, 2013
    Messages:
    8
    Likes:
    1
    Hi everybody,

    Ashafulgg, can you upload some pics of your breadboard work? Perhaps someone will be able to find some mistake.

    I think that if you put a capacitor bigger than 10 nF instead of a 270 pF your display will show you "Error/Large capacitor", so ...... are you sure you are using a 270 pF?

    Regards
     
    Last edited: Jan 22, 2014
  20. ashraful99

    ashraful99 New Member

    Joined:
    Jan 15, 2014
    Messages:
    7
    Likes:
    0
    thank you neimocol, yes i am using 270pf cap.......... i will upload the breadboard pic. i am an undergrad student of eee. the breadboard is in my lab which is closed for the week now for some project purpose.i will upload it tomorrow.
     
  21. p84vish

    p84vish New Member

    Joined:
    Jan 31, 2014
    Messages:
    2
    Likes:
    0
    please any suggestions i tried this project on breadboard..........but still showing Large CAP or error
    what can i do?...
     

Share This Page