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Hi GO! I have a question.I to do the calibration, .I measuse the resistance with 100Hz measuring frequency. It is ok maybe, but with 1kHz not ok.much more the deviation. See in the attached picture.
every value are Ω (ohm), What is the problem with the measure on 1kHz? Thank you!
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san398: See in the attached picture
Perhaps you put the wrong picture.
san398: What is the problem with the measure on 1kHz? Thank you!
Measurement of simple resistors at frequencies 100Hz and 1kHz should be roughly equal. Try to check the cleanness of the negative voltage (-5V). |
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The -5V is ok (-4.98V).I made the Baton version (power supply with 34063, not ICL7660) Any idea? |
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I measured this values:
other RLC meter - This RLC meter 100Hz ---- 1kHz
46,9 ----- 45,03 ----- 45,2
100,2 ----- 96,62 ----- 96,57
466 ----- 447,9 ----- 488
995 ----- 994,6 ----- 1044
4710 ----- 4710 ----- 4912
9970 ----- 9950 ----- 10460
46800 ----- 64700 ----- 50370
99400 ----- 99200 ----- 110000
220000 ----- 219800 ----- 275200
465000 ----- 466600 ----- 616000
677000 ----- 679000 ----- 679000
989000 ----- 996000 ----- 1686000
1500000 ----- 1520000 ----- 2760000
2200000 ----- 2211000 ----- 4460000 |
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Connect the resistor 1.5MOhm and test the entire circuit using the oscilloscope at frequencies of 100Hz and 1kHz. Carefully check the form and magnitude of sine, noise, offset, etc. Based on the values (1500000 ----- 1520000 ----- 2760000) the difference should be noticeable. |
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I found one error. The C2 (5.1pF) was not good value. I change it. In the C2 position 4,7pF is good value?.The measured values are better, but i think are not good. I check the frequency, 100Hz and 1kHz ara not stable and sinus is noisy, the frequency to change between 92-107Hz and 957-1057Hz.The frequency stability are ok?
some new measured values: Other meter 100Hz 1kHz
99600 --- 100000 --- 100000
220000 --- 221800 --- 221500
465000 --- 469700 --- 466400
677000 --- 682400 --- 694400
989000 --- 993500 --- 968000
1500000 --- 1500000 --- 1412000
2200000 --- 2200000 --- 1900000
4700000 --- 4650000 --- 2700000
You see, under the 1MΩ the values are maybe ok.I measured the 10MΩ and the meter measure 19-26MΩ. Thanks GO for your help! Any idea! |
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The frequency of sinus determined the frequency of a quartz resonator Gr1 and should be stable! Better to measure the frequency at the output DA1.1 pin 7. When measuring large resistors are included scaling amplifier (DA1.2), check it. And turn off or remove possible sources of interference (the computer keyboard, lamps, etc.) |
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I changed the quartz, results is same.I change the DA1, results is same.I change the DA5, results is same.I switch off everything that is not necessary, only switch on the scope and the power supply.
I do not know why did not work correctly the meter. Any idea?
Thanks GO for your help! |
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Which is the best variation? I attached the picture. 
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Forums that do not open the picture...
Try check the capacitors in the binding of quartz (C10, C12).
Also check the installation of the configuration bits in the programmer for the PIC16F873A:
_CP_OFF & _BODEN_OFF & _HS_OSC & _WRT_OFF & _WDT_OFF & _PWRTE_ON & _DEBUG_OFF & _CPD_OFF & _LVP_OFF
The scheme is very simple, should work 
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