correct connection search head Tesoro

[Marcello]

I have constructed the tesoro eldorado and have bought the head tesoro original them (that concentric brown with center them). I have following wire: viola, gray, orange and ground. between ground and gray I have 22 ohm between ground orange I have 22,3 ohm between viola and ground I have 0,2 ohm, but even if turn out in short it are not! why if I connect on the coil rx or an other I have marks them tx-rx fase of 180°. Someone could help me to understand as they go connects to you correct tx and rx? Thanks!

[Carl]

Re: correct connection search head Tesoro

Orange (pin 1) & shield (pin 5) are the transmit coil. Shield is ground, orange goes to the Colpitts circuit.

Gray (pin 4) & violet (pin 3) are receive. Gray goes to the non-inverting side of the preamp, green to the inverting side.

[Marcello]

Re: correct connection search head Tesoro




Hi Carl if I have well understands the search head you must be connected as in photo.

In this way I have a bewilderment tx-rx of around 20-30°.
If I also connect the same shield of tx for rx I get bewilderment tx-rx of 180° in comparison to before.

I know that the original head of the tesoro eldorado introduces a bewilderment tx-rx of 180°.
Do you think that can be compatible?

I with the wire on threads as from your indications have the followings results:
To succeed in balancing the GB I have had to put in parallel to rx a capacitor of around 40nF instead of 33nF and in this way I get bewilderment tx-rx of around 30°.
The maximum depth in air in disc is of around 26cm.

Thanks in advance!

[rudi]

Re: correct connection search head Tesoro

Do you have a pcb design of this tesoro.Are the results good off this project?

[Marcello]

Re: correct connection search head Tesoro

yes, I have build pcb of eldorado and It is a good project because the amplitude of tx is 12Vpp. GB and Disc are indipendent.
The depth really is 27 cm in air and the discrimination is enought perfect whith the search head original!

[Carl]

Re: correct connection search head Tesoro

Yes, your drawing is correct. Do not ground the violet wire. In my previous reply, I said green, but meant violet... was looking at the header wire, not the cable wire.

Where are you measuring the phases?

- Carl

[Marcello]

Re: correct connection search head Tesoro

Thank's Carl,

the phase I measure with oscilloscope double track, one on tx and the other on pin 6 of LM308.