Serbian "Most Wanted"

[eduardo1979]

Hi Eduardo.
Look the pcb that you post at #432. If you can't find i can put here with the errors, i have not any reason to say lying

Regards.... and Happy New Year

Happy New Year.

[Geo]

Happy New Year.

btw how you connected the coil, because my friend has the same???

[emoxristov]

Please tell me where the mistakes are and how to fix them. Happy New Year to all friends here in the forum. Health and happiness to you all

[eduardo1979]

You have to check your PCB with this. This PCB is what I did and it worked correctly.

[eduardo1979]

btw how you connected the coil, because my friend has the same???

The coil connections with Teknetics T2 Next SMW are: Pins 1 and 2 are RX.
PINS 3y4 are TX.
PIN 5, NOT CONNECTED.
The 68nF capacitor value should be changed. I do not remember, but I think it is 1nF or something else. Long ago I did this project and I can not remember.

[Geo]

The coil connections with Teknetics T2 Next SMW are: Pins 1 and 2 are RX.
PINS 3y4 are TX.
PIN 5, NOT CONNECTED.
The 68nF capacitor value should be changed. I do not remember, but I think it is 1nF or something else. Long ago I did this project and I can not remember.

Thanks, who pins are going to GND????

[eduardo1979]

Thanks, who pins are going to GND????

I do not remember exactly. I think I posted this post some time ago. You can open the plug Teknetics coil and check the cables to GND. What I remember is that the shield of the RX coil is connected inside the dish to the GND and needless oto guitar cord. You have to find the posts where they posted this.

[Geo]

Thanks

[eduardo1979]

Here you have a new version of SMW that works very well. I've tried with a stock coil Excelerator 10 "DD for MXT Whites 14KHz. Not designed the PCB, but I tried the project using a PCB SMW from the previous version, and I have applied the new modifications. The project looks very promising and deserves a chance. Greetings.

[emoxristov]

For this project to make a new PCB

[Davor]

This one is nice, but in fact it is a significant deviation from the original project. So why not going all the way?
Only one additional channel will introduce Fe discrimination, using a common GEB. Furthermore, the compression in the final GEB stage is less than ideal, while disc stage has no compression at all and is prone to saturation (odd delays etc.). I'd surely revisit the final stage gain blocks
Preamp is nice, yet it loads a coil with low emitter impedance. For coils in ~10mH range I'd prefer a common emitter solution. Also the 100n capacitor could be significantly reduced to improve immunity to 50Hz power lines.
Tx oscillator can become a balanced one. It would make problems with coils where either of the coil ends is grounded though.

Anyway, this is more like it. I like the way you think.

[emoxristov]

Please upload the correct scheme and PCB

[eduardo1979]

This one is nice, but in fact it is a significant deviation from the original project. So why not going all the way?
Only one additional channel will introduce Fe discrimination, using a common GEB. Furthermore, the compression in the final GEB stage is less than ideal, while disc stage has no compression at all and is prone to saturation (odd delays etc.). I'd surely revisit the final stage gain blocks
Preamp is nice, yet it loads a coil with low emitter impedance. For coils in ~10mH range I'd prefer a common emitter solution. Also the 100n capacitor could be significantly reduced to improve immunity to 50Hz power lines.
Tx oscillator can become a balanced one. It would make problems with coils where either of the coil ends is grounded though.

Anyway, this is more like it. I like the way you think.

You are right about the 100nF capacitor. This capacitor may be substituted by one or maybe 22nF 47nF by one, but the exchange phase and the intervals would have to change 47nF capacitor, which is in parallel with the RX coil to compensate the phase shift. I also like the idea of a third channel, but for lack of time I did not add another channel. I like to experience the discrimination block, using C-MOS integrated circuits decoders, to see if this can improve. Whenever I get more free time, I experience more and I will check all that with the Proteus simulator. Greetings.

[eduardo1979]

Please upload the correct scheme and PCB

The scheme is very correct. The PCB is not available for now for lack of time.

[emoxristov]

Which version works well without changes in PCB