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

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

No 1 ?

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.

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 .?

Hello Rfdiva

The PLL itself is a phase comparator! Does it have a lock indicator?

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.

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.