# PLL (CD4046) FOR 50Hz

Discussion in 'General Electronics Discussion' started by PRIYADHARSHINI, Sep 2, 2014.

137
8
Feb 6, 2014
hi,
i have designed PLL circuit for 50Hz,5v ac signal using CD4046
i have chosen the components as per the data sheet information..
can any one suggest me whether the circuit is correct or not?
or any corrections to be needed?

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2. ### KrisBlueNZSadly passed away in 2015

8,393
1,270
Nov 28, 2011
R2 isn't needed.

What value is R1? 320E? Does that mean 320Ω? If so it's much too low. Try multiplying the resistor value by ten and dividing the capacitor value by ten.

The rest of it might be OK. You haven't given enough information to be sure. But even if you did, I couldn't tell you for certain that it's OK. I can just pick up obvious errors like those.

137
8
Feb 6, 2014
thanks ..in 14 th pin i have given the capacitor value as 1000pF.
when i gave the square input to that capacitor it proDuces the charging anD discharging waveform..
Due to this i cant compare the input signal wave to vco output wave form at pin 4.what is the reason and how can i eliminate this?

137
8
Feb 6, 2014
anD i m new to PLL(cd4046)..
1.what will be the output if we give the sine wave to the CD4046?(still i have'nt try with ac.just i have given 5V square wave as an input)
2.actually we have set that the VCO input as 50Hz(from phase comparator II output).according to the capacitor and resistor values vco generate the particular frequency of output waveform.this will be given to phase comparator II ..if the input signal 50Hz (leads or lags the vco output) depends upon that the phase pulse has been generated.is it correct?

5. ### KrisBlueNZSadly passed away in 2015

8,393
1,270
Nov 28, 2011
In post #2 I asked you a question and told you that you haven't given enough information.

You have asked three more questions.

Start by answering my question and giving more information. What is the purpose of the circuit? How are you using it?

137
8
Feb 6, 2014
sorry...i want to measure the zero crossing Detector for 50Hz AC .but i have trieD with banD pass filter ..it proviDes phase shift...in zero crossing Detector i have seen the jitter effect..so i have DeciDeD to use PLL to minimize the jitter

7. ### KrisBlueNZSadly passed away in 2015

8,393
1,270
Nov 28, 2011
1. You still haven't answered my question in post #2.
2. You don't need a bandpass filter to detect zero crossings.
3. You don't need a PLL to detect zero crossings.
4. If you want to communicate clearly with other people and not p*ss them off, you should not capitalise every 'd' you type.
5. If you use a person's name as your user name, it should be your name.
6. Show me the rest of the circuit and I will suggest a proper way to detect zero crossings.

137
8
Feb 6, 2014
apologize
R2 is 320 ohm..and this circuit for tan delta measurement..i want to simultaneously measure the voltage and current in AC.
I designed the zero crossing detector using lm 358.the square wave is affected by jitter..so i want to eliminate that jitter.
so i have designed the BPF but it produces phase shift..i just known about PLL...so i have tried with that cd4046.

9. ### KrisBlueNZSadly passed away in 2015

8,393
1,270
Nov 28, 2011
Post the design of your LM358-based zero crossing detector.
How much jitter were you getting with that circuit?
What did the output of that circuit feed into, for phase angle measurement? Were you using a microcontroller?
Are you using the AC mains as the sinewave source for your tan delta measurement project?