Help Teknetics G2

[Arcoman]

I don't argue. ))) wow. I didn't know who I was talking to. he gave a piece of the scheme. I'm glad. thank you. you are man. thank you

[PimentoUK]

The XOR gate is used as a digital mixer. The digital output is low-pass filtered, to give a DC voltage. This DC voltage varies as the phase relationship between the two logic inputs varies.

It is a common part of a phase-locked loop ( PLL ) circuit, for example the CMOS CD4046, which has 3 choices of phase comparator.

[Arcoman]

I didn't know about it. can you give more details. unless of
COurse you're busy.

[PimentoUK]

A simple introduction:
PLL introduction

PLL phase detectors

An advanced course, pdf:
advanced PLL

The CD4046 PLL IC datasheet pdf:
CD4046 datasheet

I do not know how this XOR gate phase comparator is used in the Goldbug circuit. Maybe to synchronise one oscillator to another ? The "slave" PIC micro that is used to drive the complex LCD will likely operate at a lower clock frequency than the main "brains" PIC. Having two micro's generating independant electrical interference could be a problem for the analogue parts of the circuit. Synchronising one micro to the other may help control this.
It is a technique I have seen versions of in several metal detector designs.

[Arcoman]

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