BARACUDA-Legend-1

[kt315]

you do not want to notice a capacitance GATE->SOURCE-DRAIN. you need fast charge and fast discharge this cap. thats a time.
the time kills your good idea that MOSFET is better than NPN.

[Andi68]

A Darlington transistor can also switch high frequencies.
In the frequency range of a PI that does not matter anyway

[Cladpirate]

in the beginning of this thread it is noted that this detector gains the ability to discriminate when the tip127 is used. if I am understanding correctly I will need to adjust the 1000uf capacitor to suit?

[kt315]

nice price for Ikelite case https://www.ebay.com/itm/Ikelite-Case-5280-Underwater-Camera-Housing-Unit-w-Camera-and-papers/273654096038?hash=item3fb70e20a6:g:bjoAAOSwNkJaIwk Z:rk:47f:0
your chance.

[kt315]

in the beginning of this thread it is noted that this detector gains the ability to discriminate when the tip127 is used. if I am understanding correctly I will need to adjust the 1000uf capacitor to suit?

not. with TIP127 you need slightly to move opamp balance into a side, positive or negative. need experiment here.

[kt315]

use SMD parts for the Bara and you'll get SMD board. thats is NOT hard you think about.
my board is UNIVERSAL to do both types of placements.

[MartyJ1963]

Hiya all,,,,probably a silly question, but can I use a J113, BF245C OR a 2N3819 as a substitute for a MPF102 in the Barracuda Legend project? I thought I'd have a go at building the first Barracuda because I've run out of projects to keep myself busy,,lol. Thanks in advance for any help,,,Regards,,Marty

[crni1]

You can all of them and the BF 244 as well as some other substitutes just watch the layout of the feet.
The menu works best with BF 244

[nonkapo]

I'm using bf256B and Baracuda is performing as it should. Got MPF102 on the Geotech one, but they cost me 4$ each.

[kt315]

i resorted out all mosfets' prices on ebay and discovered that bf256 has smallest price. thats why bf256 was choiced while in the schematic i showed 2n5485.

[Andi68]

I took BF247B

[MartyJ1963]

Hi all,,,,,Thanks to all the replies,,,very much appreciated,,Regards,,,Marty.

[kt315]

http://web.archive.org/web/199902031...ectronics.com/

[kt315]

Hi seller
I have bought your bare board for the barracuda detector

I am not any good at electronics but was hoping to have someone build it for me do you know of somebody to do this project and what it might cost and where to get the other parts?

Thank you
----

a buyer asked me in PM. who can help this collegue in United States to build bara on mine board?

sincerely yours

[ramin]

Hi to all

I built geotech barracuda rev a

according to mr qiaozhi said: the detector can sens a coin from 28 to 30 cm but in mimnimum sample delay and with minimum of pick sound
also the detector is perfect on sensing nonferrous metals like copper but maximum depth of detection for a 15 ? 15 cm copper sheet with 40 cm coil is about 50 cm and maximum depth of detection with this coil is 80 to 90 cm for 50 * 50 cm metal objects
Also you can increase depth of detection by changing tx pulse width
for this purpose i replace the c5 by capacitor 15 nf and as a result tx pulse width increase to 150 us and frequency decreaces to about 300 hz
Also with this changes you have to increase r4 to 2.5k
and in my opinion you should increase damping resistor to 470 ohm and a little change on resistance of coil with series resistor 1R

Regards