Original device

[ApBerg]

Nice info

Hello Gervm.

Thank you for the nice info !

Best regards.

Ap

[Gervm]

Author also writes obout cable betwin search head and registrator. It can be any lengh - short or long - important only one - good quality of isolation betwin two wires becose search head inserted to shoulder of bridge and bad isolation may produse instability.

[Gervm]

Several words about sensitivity of this device. Author writes that when they were making the unit ... they had not good transistors... and if yor put good parts - result will be better. nevertheless thier detector was enough stable and could find with ferrite coil - 25mm coin at the depth 120mm, metal disk with diametre 250 mm at depth 460mm. On air sensitivity was on 30% higher than underwater. If they used loop coil with diametre 300mm sensitivity incresed in 2 or 2 and a half times. But with large loop device did not see very little objects.

[Esteban]

Gervm, very interesting device. First time I see this kind of wound of coil around ferrite, is not usual. You're making a good job. Continue, please!!!

[Gervm]

Total view

[Gervm]

Oh, I found its "father". It had no cristal but used different coils.

[Gervm]

Here is the circuit of the first model.

[Gervm]

It had 3 search heads. The first was ferrit on high frequency. The second was ferrit on low frequency (for sea). The therd was loop coil with diametre of 360mm!!!
In this more old device ferrite search coils had usual winding of turns.

[detectoman]

hey gervm these model of detector is of collection, very strange, very thanks for post these gem of old implementations, muy agradecido con usted por ser tan amable al compartirnos esos geniales' detectores gracias se mira un diseno unico y muy agradable