PIC based high-resolution cap meter

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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
 
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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.
 
picbits said:
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.
Click to expand...

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

Thanks by information.
 
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
 
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
 
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.
 
So, you think i should try to build it on breadboard and see the results?
Click to expand...
Yes!
Simulators are all well and good, but unless you spend LOTS of money on them, they cannot simulate everything.

JimB
 
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.
 
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?...
 
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
 
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
 
ashraful99 said:
yes i did have that cap.i tried the circuit again but did not work.i am still working on it.....
Click to expand...

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
 
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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.
 
please any suggestions i tried this project on breadboard..........but still showing Large CAP or error
what can i do?...
 
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