Electronic-Nulled Loops

[dbanner]

A scope is required to set up the circuit for sure, the trimmers have to adjust the inputs (blue and green) from the Tx coil to synchronize them with the 555 waveform in order to work with the truth table of the 4051 for the job of the circuit.

[Altra]

Few more things were missed. The electronic potentiometers are paralleled, both pin 3's are connected together as well as both pin 6's. I've updated my schematic. I think it's pretty much done. But it may be that there are still some unknown error somewhere.

Looks good. Do you know how the opamps and comparators are connected to the power supply?

[dbanner]

That's good to know. The 4051 has vdd (12v), vcc digital ground(?) and -vee or analog minus(B-)?

It's important we know the power connections for the digital pots.

For this circuit, the photos show pin 6(inhibit/enable) pin 7(Vee) and pin 8(Vss) are all connected to ground.(4051 chip)
The datasheet has some interesting things to say about setting the Vee.

[dbanner]

Looks good. Do you know how the opamps and comparators are connected to the power supply?

I forgot to put those didn't I.

[dbanner]

Good job, nice and clean diagram. There is still no +5v connection to which pin of the 4051 system does this path go?

Seems I was wrong, it looks very much like this track is output of voltage regulator. I will have to correct my schematic again.

[Mario-j23]

Yes, this path is the output from the voltage regulator, probably +5v
Connection to US 555 pin 2 and 6 is not possible! Look at my PCB and the red upper trace.
The connection will cut the +5v and GND lines! Something doesn't feel right here.

[dbanner]

Yes. You are absolutely correct.

[Mario-j23]

I discovered one more ERROR. In the forum posts about DMC IIb there is information that the inductance of the Rx coil = 8.42mH (FAKE). correctly RX=5.42mH. My colleague YOYO27983 also made a mistake by replacing Tx with Rx in the DMC VLF diagram (correctly Tx = 2.5mH, C1 = 47nf, C2 = 470nF, F = 15.39kHz, RX = 10.7mh, C = 10n, F = 15.38Khz ) I am one step away from starting Nautilus, I still need to connect the coil socket. Does anyone have a photo of the eight-pin DMC IIB coil socket connector from the printing side? I will be grateful for your tips. Greetings and wish you a healthy and happy Christmas.

[dbanner]

555 configured as one shot monostable pulse generator. I should have looked more closely at your pcb layout. So pushing the slb switch merely triggers a pulse which enables the electronic potentiometers to do their thing. The pulse should be long duration maybe 3 seconds or so, after which the digital pots are disabled. Maybe that's how it works.

[dbanner]

Schematic. Now I hope I am a bit closer.

[Mario-j23]

There are two power sources +12V from Dmc and +5V (probably) from the stabilizer on the autotune board, which is not taken into account in your diagram. It seems to me that CK can take the signal from lm393 pin 2 and pin 6 where there is 0V on the nautilus board.

[dbanner]

Main board lm393 pin 2 or pin 6. Those are the disc and ground balance phase shifters taking signal from the Tx oscillator waveform. So CK could mean the Tx clock?

[dbanner]

Or do you mean from 6 and 2 of 393 at the end of the filters section.
why would it connect there?

[dbanner]

From this picture it looked like CK(white wire with purple stripe)is going through the hole in the main board. To the top side.

[dbanner]

I just now realized that there is a CD4024 chip on main board. CK wire goes to pin 3 of CD4024. Now I think everything is closer to being solved.
I compare the 2b board with the 2ba board. On the 2b board nothing is connected to pin 3 of CD4024. So this question is put to rest.