TEKNETICS TEK S/T

[kt315]

no data on the coil, not exist. even so you can see on the schematic TX frequency noted. it is 6590 Hz. sure like Whites uses.

[dbanner]

So far as I know, Payne used 12.5kHz on viper and cobra II and treasure baron series, and 6.59kHz on the S/T.

But the Search coil on the S/T looked very much like the stock bounty hunter 10 inch coil. TX is 2.45mH in parallel with 240nF, tuned to 6600Hz. RX is 2.45mH. RX resistance is 8 Ohm

[dbanner]

Here is my take on the S/T. I haven't entered the component values as yet. It is configured for dry land, but I still have to figure out some mode switching details.(setting gnd balance, tune and reset, etc). I used different Tx and phase drive arrangement. I also intend to change the power supply circuit. But at least now it is easier to study the structure of the circuit.

[dbanner]

One thing I noticed is that the switching power supply upconverts to 30V for the supply to the Tx(black sand/salt mode). This certainly will draw a lot of power from the batteries. In addition, the transistor which drives the coil is on a heat sink.

[dbanner]

Complete except for power supply, which I intend to change.

[dbanner]

Here is my solution for replacing the switching regulator. I used a 555 to generate the Tx clock and a voltage doubler circuit synchronized to the Tx frequency. It works good in simulation. Only remains to include scheme of power supply for the 9V rails and some other minor details to tidy up the schematic. I will redraw the completed circuit in Kicad or diptrace and post it. Maybe I can get some help to design a 2 board PCB for the schematic.

[dbanner]

"The S/T has a choice of a single, two or three tone feature. They are not anything related to a Mark 1 but the tones are a pleasure to the ear. I prefer to use the 3-tone feature with the S/T, Most gold jewelry signals fall in the lowest tone range and higher conductive such as copper pennies, dimes and quarters fall in the high tone range. The target range can be tweaked from a trimmer pot inside so that higher conductive targets fall in that third tone window, Forgot which trimmer pot it was but remember doing this so that some of the bottle caps that fell in the upper tone are now in the middle tone window. "


I read this quote somewhere. So it seems that the S/T is a 3 tone machine. Nice.