BARACUDA-Legend-1

[BKY1337]

My housing is a 27cm Mikron BG housing for DD coils. I want to build a single loop coil with graphite shielding.

https://www.ebay.de/itm/2-pc-metal-detector-coil-housing-27cm-10-5/122932172646?hash=item1c9f541766:g:ErQAAOSwfZ1WXyVA

[kt315]

leave it for VLF project. buy 16-18cm housing for the basket type coil.

[BKY1337]

I have bought one set (2 pieces) one for TGSL and one for Barracuda.

I guess 18cm is too small for me. Are the normal coils not good?

[Qiaozhi]

Ok, can you tell me what this mod does? Will i have more depht or more sensitivity?

Read this ->
Building the Geotech Baracuda (Rev-A).pdf

[BKY1337]

This says that the depht doubled from 6 inch to 12 inch with a 300uH mono coil.

I think i will build such a coil and i will use a red LED which should work.

[homefire]

That also included the Resister Mod.

[Andi68]

And what does it mean "all diodes 1N914" or better?

What makes a diode good for pi-detectors?

[homefire]

Read up on Diodes and there purposes in life. Just use the 1N4148 in place of the 1N914. They both perform the same function but the 1N4148 is more robust with some higher Voltage and Current Ratings. These Diodes are usually used for Voltage Steering and or Light Duty Protection circuits.

http://whatis.techtarget.com/definition/diode

[Andi68]

Thanks, I think I got it wrong.
The diodes are very similar according to the datasheet.
Now I understand it, I see, I have to improve my english

[BKY1337]

I have a problem with the adjustment of my Trimmers.

Can somebody tell how i need to adjust them?

I saw in the PDF that i need to bring the voltage at pin6 of the op amp to 0V and then i need to short the delay pot and
measure the voltage between gnd and Pin7 of the same op amp.(LF353). This voltage should be -2,1V.

But i tried this and the voltage doesn't change.

Its the kt315 Rev-B small board.

[homefire]

Try grounding the other end of the pot.

[BKY1337]

I have desoldered the IRF . Then i realized that i need to measure at pin1 instead of pin7.
I still cant change the pin voltages with the trimmers.

I have two testpoints at the trimmers i can measure a changing current there.

Do i need to get -2.1 V? and where?

Which Pot do you mean? Delay?

[BKY1337]

Grounding Delay pot doesnt change anything.

I tried to adjust the 0V at the wrong op amp.

But i still need to find out how to bring the other one to -2.1V and which pin.

My Pin1 is about 600mV and i can change it with the trimmer but not to -2.1V.

[kt315]

please ask the forum.
you are overloading my PM box by bare requests,

you have to get zero voltage (balance) on U1 pin6, output, or Test point 1 by tuning of R39 trim.

Yes , i already did this without IRF. But i need to know how i tune the other trimmer.

My Pin 1 (U2) shows me about 600mV and i can turn the lower trimmer until i get 250mV or something like that.
But not the wanted -2.1V.

Do i need to get -2.1V?

i say you again - you need o-scope in your kitchen room. you operate by categories that i do not use and
ask me HOW to measure AC signal with EMI noise in your home by chinese multitester.

YOU HAVE TO GET THE ZERO NULLING IN POINT T1. why you ask me about DC voltage on U2
if you have to get ALL AUTOMATICALLY. no more adjust in this primitive schematic.

[kt315]

zero level