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4046 simulation, 74HC4046 simulation

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elkesan

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Ok,
I follow this thread: https://www.electro-tech-online.com...ttGv33l0MCJ1ycBcj3XgUgGfYQGxpLgPVI_PBWJviNzKE

Final result is FM-demodulator. Carrier frequency 82 kHz, need demodulated signal and carrier detect.

Need help found fully working model for 4046 or 74HC4046- final circuit will be made with 74HC4046.


Look this model not work properly. I simulate days and days, and results are what they are. Then I think simulate it step by step, first "how VCO work".

Using days google I found it secret formula:
fmin = 2/(C1R2)
fmax=2/(C1*(R1IIR2))

Eg. this 82 kHz I can try eg. fmin 60 kHz, fmax 120 kHz. With this frequences 470 pF looks good. Using formulas I found R1 = 35k and R2 = 71k. Formula attached to zip-file in excel-format. Brains say, "470 pF, 35k, 71k, very good values".

Okay. Then 4046, 5V power supply and VCO-in 0...5V. Result: 18 kHz...48 kHz. This is most easy test.

Then, I put values (35k, 71k, 470 pF) to online calculator. Using google it is possible found many 4046 online calculators. Result: many hundred kiloherz.

SO: Own calculations with formulas (fmin=2/(C1R2) etc make one result. Ltspice simulation make one result. Online calculation make one result.

1: Is it possible found really working model for 4046?

2: How I can calculate fmin, fmax so R1, R2, C1 values, looks my formulas are wrong? (My formula make one result. Online calculators make one result. Ltspice make one result. )

3: Fm-demodulator, reason I cannot believe ltspice, what values are good for filter between PLL stages? "100k, 1n" when we use Stetson Theorema, but it is low pass filter--- f = 1/RC, if we select 1nF, resistor is 12 k. So, I try found any logical application note for this, but not possible. Maybe this "f = 1/RC" is good, f it is it 82 kHz... of course I can simulate this, but reason 4046 model I cannot believe it is ok...
 
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