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Help needed desperately with PIC LCF meter

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hi,
The 3.2768MHz crystal is essential, any other frequency will not give the correct readings.
The program is written only for a 3.27MHz crystal.

you guys keep ignoring my posts..why? there's nothing could
advice me for the problem?

this instrument is rather simple other than the PIC there are
a couple of resistors and capacitors, i can't see what can cause
such mulfunction..


Nothing i can say....Me too just planning to build this stuff...:(
 
you guys keep ignoring my posts..why? there's nothing could
advice me for the problem?

this instrument is rather simple other than the PIC there are
a couple of resistors and capacitors, i can't see what can cause
such mulfunction..

hi lynx,
I am not ignoring you, its just I cannot think of a quick fix.
A number of members have built this project and it runs OK, also you said that your build was working OK until you modified it.

I would suggest that you restore the project back to its original design, [ the one that works], this may highlight what has caused the problem..
It sounds as though you have a floating input on the IC.???
 
hi ericgibbs and sorry that i complained :)
i really need to fix this instrument because it's useful to me...

concerning the floating input you said... i guess such thing can happen
in case i forgot rewire any of the cables that used to go to the rottery swich
right?
 
Hi Lynx,

Like Eric I am struggling to imagine whats going wrong.

I have looked over my original schematic and circuit drawing and can't see anything that would give the false readings WITHOUT giving other symptoms.

I am posting the original PDF so you can examine and fault find from it in case you don't still have it but without actually seeing your mods I don't think anyone will be able to help much. What about some really clear pics of the board and wiring?

Al
 

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hi Al,
I still have all our notes/drawings on my hard drive, under 'Al's Stuff'...:)

I feel sure that the latest OP has a wiring error in his converted version, most likely an open CMOS input or missing ground link.
 
Hi Eric,

Hope you're keeping well mate, like you I seem to think that the changes made may have caused something to go awry.

Apart from the problem I had building this, which was the missing R/W ground that you pointed out I have not heard anyone say theirs was faulty.

Your advice stands - put it back to original. I don't understand why he modified it unless it was size considerations as the 3 pole switches are a bit space hungry!

Al
 
Hi mate,

Do you still need the 3.2768mHz crystal?

If you do then PM me your address and I will send you one.

Al

Thanks for the offer mate..But I'm from the Philippines...:( The cost of shipping I think is enough to buy a dozen of xtals..:D
 
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Hi

sorry for my delay to reply to this topic
here's a photo of my wiring...

if we can make it work right.. it would be great!! :)
 

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Hi

sorry for my delay to reply to this topic
here's a photo of my wiring...

if we can make it work right.. it would be great!! :)
hi lynx,
Post a picture of both sides of the PCB, showing the whole board surfaces.
It may be possible to trace the problem from the pics.
 
hi lynx,
Post a picture of both sides of the PCB, showing the whole board surfaces.
It may be possible to trace the problem from the pics.

ok thanks for your support! :)
here's more photos..
 

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ok thanks for your support! :)
here's more photos..

hi,
Got your pics, I will look them over...
EDIT:

Check this track for a break at this point... I will keep looking.

EDIT2:
It appears C7 is also missing.... 1nF see 3rd image
 

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Last edited:
Check this track for a break at this point... I will keep looking.

EDIT2:
It appears C7 is also missing.... 1nF see 3rd image

Hi

unfortunately that's not a track break..it's just a scratch and the copper
is visible, but it's great that you noticed such a little detail in a photo :)

C7 is not missing it's the capacitor between the two resistors.

can the problem be the crystal? but the PIC starts...
 
Hi

unfortunately that's not a track break..it's just a scratch and the copper
is visible, but it's great that you noticed such a little detail in a photo :)

C7 is not missing it's the capacitor between the two resistors.

can the problem be the crystal? but the PIC starts...

hi.
I understand you just want to use the Inductor section of the LCF.??

If so, this image shows all you need for the oscillator section.
 

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hi,
As you dont want the CAP function, you can modify the pcb as shown in this image.
 

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Hello everyone, I would like to build the LCF meter, but first I would to simulate it in Proteus Isis 7. It doesn`t display only 0Hz or Inductor Timing , using the code uploaded by bigal_scorpio for PIC16F628A . Could anyone help me please? I could try to send the project and lake a look at it . I`m an amateur and trying to learn electronics. Thank you
 
hi,
As you dont want the CAP function, you can modify the pcb as shown in this image.


Hi..

still frequency and inductor values go up and down

with a 3.3uH inductor it says:

18027Hz
15.802uH

18039Hz
9.024uH

18002Hz
29.364uH

etc......
 
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hi lynx,
If you are in the UK, you could post your project to me and I will fix and return.
 
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