TEKNETICS TEK S/T

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[ATTACH]n428899[/ATTACH] A slim down version of this scheme should make an awesome 2-tone beach machine. Trying to understand the mode switching circuitry.
Draft13.asc.zip

[kt315]

DB you are so active but why you are not able to inform the forum about your county?

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Ok, I'll do that soon enough.

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Looks like in (black sand/salt mode) it puts 30+ volts across the Tx coil. Hence the boost regulator. One of those china boost modules could be fitted to a slim down scheme which is rigged to operate only in black sand/salt mode, thus eliminating all the toggle switching circuitry?. Maybe. A specialized beach detector with 2-tone discrim. I'll draw a lite schematic version and post it to get some feedback on what you guys think.

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need to figure out a manual "pot" sensitivity control instead of the fancy pancy toggle "up" or "down" to increase /decrease sensitivity. That shouldn't be to difficult.
This is accomplished I believe via U216 (the one with Q11) and its circuitry. Still unsure how it all is supposed to work, I need to read the operators instructions for the TEK S/T.

[kt315]

Ok, I'll do that soon enough.

Thank you. i will do a video with a story how i bought the schematic, later.

[Altra]

Not much user info out there. I used a S/T on land, it was excellent. Not sure about saltwater performance?

https://www.findmall.com/threads/teknetics-s-t.344009/

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Not much user info out there. I used a S/T on land, it was excellent. Not sure about saltwater performance?

https://www.findmall.com/threads/teknetics-s-t.344009/

could you describe, if you can recall, how the sensitivity adjustment worked on the S/T?


very unusual housing for the electronics, it was a 2 board design, I think. Those search coils look like the standard bounty hunter coils. No problem getting those.

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I think I can make a very good beach detector based on the S/T scheme.

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[ATTACH]n428899[/ATTACH] A slim down version of this scheme should make an awesome 2-tone beach machine. Trying to understand the mode switching circuitry.
Draft13.asc.zip

The circuit uses primarily +9 and -9 Volts. The +6.5V and -6.5V in my sim is redundant.

[Altra]

could you describe, if you can recall, how the sensitivity adjustment worked on the S/T?.

That was about 30 years ago, so a little foggy. As I remember it, you would blindly press the spring loaded switch down until it quit chattering and up until it was unstable. What I do not recall, is if it took repeated toggles or if you could just hold the switch? I noticed in the Findmall thread Sven who is a member here owned one. Maybe he could give a clearer description?

[dbanner]

Very interesting circuit no doubt. LM3578 switching regulator has internal oscillator (pin3) which can be set using an external capacitor, the formula given in the datasheet is:

F(osc) = 8×10 ^−5 /C 1

Now looking at the schematic of the S/T shows a 1.5nF cap is used to set the internal clock. This is also tied into the Tx circuitry. Using this formula I calculate 5.33kHz. Is this the operating frequency of this detector? Everything is nicely synchronised and tied together. That's very nice indeed.
lm3578a.pdf

[cnckecgo]

I did a lot of trials and tests in the field. The detector was working great I found some nice coins in a very deep place. Current detectors cannot find money at this depth. The detector had a variable tone of voice. extremely powerful detector. there were two circuit boards mounted on top of each other But it broke down and I couldn't fix it and eventually had to throw it away. I tried many detectors but my mind always stayed with this device. I couldn't find it anywhere It will throw away the current new generation devices. very sensitive to gold .My mind is still on this device.

[Altra]

Very interesting circuit no doubt. LM3578 switching regulator has internal oscillator (pin3) which can be set using an external capacitor, the formula given in the datasheet is:

F(osc) = 8×10 ^−5 /C 1

Now looking at the schematic of the S/T shows a 1.5nF cap is used to set the internal clock. This is also tied into the Tx circuitry.
[ATTACH]n428919[/ATTACH]

You will need to figure out how to synchronize your Chinese boost module to the Tx. The modules I have do not have external timing caps, but they do have enable pins. Possibly you could blip the enable pin with the Tx to keep synchronized?

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Problem with china upconverter module is switching interference, and not possible to synchronize everything. Better to stick with original power supply scheme using LM3578.

The more I look at the S/T schematic diagram, the more impressed I am.