Tarsos detector vlf turkey

[Atul Asthana]

Where can I find the latest schematic?

Where can I find the latest schematic and information about construction/adjustment and coil design?

[Serg_kk]

I join to Atul Asthana, much is not clear. I should use the translator. Which probably not correctly translates. And in the scheme there are corrections which concern coil. How it is necessary to do, how on the scheme or how on the finished correction?

[dfbowers]

Autotune Schematic

All,

I have finished 2 working circuits but have not been able to get the autotune option to work correctly. Has anyone in the forum been able to get the autotune option to work? I have attempted to draw in the autotune circuit from the pieces I could find on the forum. Does anyone have a complete schematic?

Thanks.

Don

[TARSOS]

hi friends.

here is corrected schematic and separate tune pcb

regards..

[dfbowers]

Tarsos Schematic

Below is the complete and corrected schematic.

Don

[Serg_kk]

Hi all !!!
Who has a corrected trace (pcb) for this scheme?
Better in format LAY.
Thanks

[Unregistered]

Work?TL061 output is PARALLEL in TL071 input.FANTASY made in Turkey.

[goldmont]

Hi
i am getting the coponents to start this project, and i ahve a few questions...
1.the resistors must be 1w .25 or .5 ?
2.The capactitors what v must be?
2. in the drawing of the pcb + components what is before the speaker?

Thanks

[dfbowers]

I used 1/8 W resistors throughout, although you may want to consider something a little larger for the 22 ohm resistor before the speaker.

The capacitors I used are all 25V except for the 6.8n capacitor in the tx coil, you may want to consider at least 50v.

I'm not sure what you are asking about "what is before the speaker".

Don

[dfbowers]

Autotune variation.

I propose a mod to the autotune that makes the Tarsos a little more usable in bad ground. It provides a "fast" autotune to help filter out the effects of bad ground. I also added a mod to the threshold which makes setting it a lot easier, which is critical to the performance of the detector. I built mine this way and I get half decent performance when I take it outside and use it in the ground.

Also, another worth while mod is to put a 100K pot in place of the 1M resistor between pins 6 & 7 of the TL072. It tones the detector down a little and actually provides a threshold that can be monitored.

Don

[Friday]

Hi...

Great job dfbowers...Did you test it on the ground? If it works good on the ground I will make your mod...

Regards...

[humhum]

Very thanks Dfbowers.

Благодаря.

[dfbowers]

Tarsos coil tuning

Hello Tarsos,

Can you say why the particular values for the tuning capacitors were selected for the Rx & Tx coils (6.8n & 10n)? It would suggest that the circuit was designed not to operate in full resonance. Maybe to enhance discrimination somehow? I have built two so far and the circuit seems to function much better if the coils operate in full resonance.

Also, Can you say why your design has no shield on the Tx coil?

Thanks
Don

[pipi]

Very interesting to me is that whether the detector is working. Is not possible simultaneously using ground balance and discrinination.

[dfbowers]

Ground balance and discrimination

Yes, you can use a detector with discrimination, without ground balance. It's tough! You must keep the detector at a very constant height and move very slow. especially in bad ground. That's the way we USED to do it with the old T/R type of detectors, OR you could ground balance, but not both at the same time. The fast autotune works good with the Tarsos though as the detector looks for fast change in phase shift. You can still get a false signal if you raise or lower the coil quickly to the ground.. but for the most part, the autotune circuit filters out most of the ground effects.

Don