phase detec circuit

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radium98
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phase detec circuit

Post by radium98 » Wed Jul 14, 2021 6:34 pm

i would really need to be helped
now i dont have access to dual channel oscilloscope.
my prob is that i have two 2 signal out of phase , and i need to make a little circuit , that have eg 2 leds like the one to tune the vco in nrgkits, but this time i need to see if both phase are inphase , like leds go off , please advice and help

radium98
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Re: phase detec circuit

Post by radium98 » Thu Jul 15, 2021 7:55 am

download/file.php?id=886

what modifications can be done to me compare if both two inputs signal are in phase
here both volatge are equals so both leds go off , how do i use it to compare both signals ,dont have now a scope

radium98
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Re: phase detec circuit

Post by radium98 » Thu Jul 15, 2021 8:44 pm

No 1 ?

Albert H
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Re: phase detec circuit

Post by Albert H » Fri Jul 16, 2021 1:32 am

radium98 wrote: Thu Jul 15, 2021 7:55 am download/file.php?id=886

what modifications can be done to me compare if both two inputs signal are in phase
here both voltage are equals so both LEDs go off , how do i use it to compare both signals ,dont have now a scope
That circuit just monitors the PLL loop voltage. For best modulation linearity, the loop voltage needs to be about 3.2V - that circuit was to allow users to fine-tune the VCO trimmer to the optimum point. It does nothing to monitor phase or anything else - it just compares the VCO loop voltage with a 3.2V reference derived by a potential divider from the 5V logic supply.
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Rfdiva
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Re: phase detec circuit

Post by Rfdiva » Fri Jul 16, 2021 6:24 am

Thank you Albert yes i know .But i just ask is there a way to modify it or something that work like it or with a 4011 to function like a phase comparator .of two signal are equal in phase a led should turn out .?

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sinus trouble
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Re: phase detec circuit

Post by sinus trouble » Sat Jul 17, 2021 1:07 am

Hello Rfdiva :)

The PLL itself is a phase comparator! Does it have a lock indicator? :?
I am as stupid as I look! :|

Albert H
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Re: phase detec circuit

Post by Albert H » Sat Jul 17, 2021 4:51 am

If you're using a discrete component PLL - like my CMOS one - it's easy to add a lock detector and indicator to the phase comparator IC (the 4046). You can make a very effective phase comparator and lock indicator with a dual bistable and some NAND gates. I'll put the circuit up here if it will be of any use.
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Albert H
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Re: phase detec circuit

Post by Albert H » Tue Aug 03, 2021 12:07 am

Here's how to do a really good phase comparator and locked / unlocked indication. This circuit has been used in some very high quality transmitter (and receiver) applications.
Phasecomp.png
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