hi lynx,
I assume that on your version of the LCF meter that you have the SET push button connected.? and that you carry out the Correction procedure as explained in the pdf.?
I have built the inductor osc section and it works OK, testing using a number of 4011 gave wide differences in the base frequency [ ie: when the test probes are shorted together]
The 10Kpot has a VERY wide range of frequency settings, I guess thats why the SET push button is used before measuring.
The base 4011's frequency outputs remain stable enough, over many tens of minutes.
no i'm not in the UK, by the way i got a small oscilloscope...
and shorting the leads and measuring between the minus of the battery and the
pin 12 of the uC the frequency is around 20KHz and fluctuates a little bit up
and a little bit down
no i'm not in the UK, by the way i got a small oscilloscope...
and shorting the leads and measuring between the minus of the battery and the
pin 12 of the uC the frequency is around 20KHz and fluctuates a little bit up
and a little bit down
hi,
With the test leads shorted together, the frequency on pin 12 of the PIC should be about 300KHz, if its only 20KHz check that the inductor wired to the PCB is really 10microHenry.!
Also look at this image, , is that pin hole soldered in correctly.??
What are those long black wires fastened to the end of the R5 resistor.?
Its hard to see on your PCB images.
EDIT:
I cannot see the 'L1' 10uH inductor on the PCB, could you mark it for me.?
hi,
With the test leads shorted together, the frequency on pin 12 of the PIC should be about 300KHz, if its only 20KHz check that the inductor wired to the PCB is really 10microHenry.!
it's hard to tell right now because of HMA around the inductor..but as far as
i remember the value of the inductor is correct. turning the pot to the right the frequency
can go up to 500KHz turning it to the left goes close to 19KHz
Also look at this image, , is that pin hole soldered in correctly.??
What are those long black wires fastened to the end of the R5 resistor.?
Its hard to see on your PCB images.
i was wondering... other than ericgbbs nobody else can contribute
with some knowledge?
after all this talk and and tests..i believe the problem with my LCF meter got norrowed down to
4011 gate, something is wrong with the oscillator..but what is wrong? can that be saturation of the
gate which makes the oscillator not that steady?!
i also want to add that when i tried to measure the inductance of a transformer
the results where steady, so i'm very confused with all this issue.
i appreciate ericsgbbs try to help me...also anybody else willing to give a farther help!
Hi...
i also want to add that when i tried to measure the inductance of a transformer
the results where steady, so i'm very confused with all this issue.
hi,
Watched the vid.
The frequency of the oscillator is increasing with time [ which I guess you realise] this will give an apparent decrease in the inductor value.
Have you monitored accurately the supply voltage on pin #14 of the 4011, while you are taking a inductor measurement, lets know what you see.
hi lynx,
Ref your PM's
I have relooked at the project pictures and only error I can see is the way the SET switch is connected.
All it does is link two pins #1 and #3 on the PIC.
Pin #1 is supposed to go to +5V via the SET switch and if you are only using the inductor section pin #3 is connected to +5V.
I fear, too long wires connecting to switch might cause problems of instability. Check if you can reduce the wiring to bare minimum.
Many other designs, in fact, recommend on board switch with suitable pcb artwork , let it be rotary or sliding.
I fear, too long wires connecting to switch might cause problems of instability. Check if you can reduce the wiring to bare minimum.
Many other designs, in fact, recommend on board switch with suitable pcb artwork , let it be rotary or sliding.
hi Sarma,
lynx is making a 'cut down' version of the LCF meter, he only requires the Inductor test function.
So he has dropped off the Select switch, when doing this he has made a mistake of connecting PIC pins #1 and #3 together.
BTW: he did make the full version which did work.!
Thanks Eric. For Inductance meter, perhaps one design by Phil Rice of Australia is found to be best
it also works well for C . resolution appears Good. for the concerned issue i would join back shortly
PS: the values of C5a& b and C6 a&b are expected to be close tolerance such as 1%. This is one major cause for instability, once other things are attended to. See the component list of the article concerned. We had used such accurate caps buying from Farnell.Of course our design (phil Rice )used 1000pF 1%.
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
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