Barracuda build

[Mumpy1951]

Hi there all you boffins/experts. I am new to the forum and have little to no knowledge of electronics, but nevertheless I am intrigued by projects in this field. I love wiring and assembly and am in the throes of building the Barracuda PI detector. To date I have reached stage 4 without any apparent mishap but have now encountered the coil building stage to further the construction. I do not possess an oscilloscope and am trying to get through the process with a multimeter. Any way I would really appreciate any advice/assistance with building this coil so I can move forward. Thanking anyone in anticipation
Dave

[Qiaozhi]

Hi there all you boffins/experts. I am new to the forum and have little to no knowledge of electronics, but nevertheless I am intrigued by projects in this field. I love wiring and assembly and am in the throes of building the Barracuda PI detector. To date I have reached stage 4 without any apparent mishap but have now encountered the coil building stage to further the construction. I do not possess an oscilloscope and am trying to get through the process with a multimeter. Any way I would really appreciate any advice/assistance with building this coil so I can move forward. Thanking anyone in anticipation
Dave

I would suggest that you make a simple mono jumble-wound coil for the Geotech Baracuda. You can use the Coil Calculator at the top of the Coil forum to determine the correct number of turns for the size of coil you require.

For example, an 8" (~200mm) diameter coil using 0.56mm diameter copper enameled wire will need 24 turns for 330uH inductance. The Baracuda design requires quite a low damping resistor value, and I've found that 330R is a good value to start with. There's no need to agonize about getting everything spot on, and a simple mono coil will work quite well. You don't need to use enameled wire either, as insulated hookup wire will be ok.

To understand what's going on with the electronics (especially with metal detectors) you really need an oscilloscope.

[Mumpy1951]

Thanks Qiaozhi

[GeoMax]

Hi Mumpy1951,

you can get a brand new oscilloscope on ebay for about US$60,- already. Here the link https://www.ebay.com/itm/363543463635?
The should already work for you.

GeoMax

[kt315]

Hi Mumpy1951,

you can get a brand new oscilloscope on ebay for about US$60,- already. Here the link https://www.ebay.com/itm/363543463635?
The should already work for you.

GeoMax

ahaha!
Shipping:
$75.96 International Priority Shipping to Lithuania via the Global Shipping Program

[GeoMax]

Hi Kt315,

yes, the shipping from the USA to your place is quite expensive. But if Mumpy1951 live maybe in the USA and this is then cheap, because shipping inside the USA is USD 9,80 only. That is a very reasonable price for shipping. In your case I would rather check out eBay Germany or UK. They have there much cheaper shipping rates to Lithuania compare to US shipping. It always depends were you life on this planet.

[Mumpy1951]

Hi there
I have managed to get to step 5 of the Geotech barracuda build but have hit a problem. The test at this stage is to monitor the voltage on pin 6 of U2 (NE5534) and to adjust said voltage by means of the 100k trimmer (R6) to give 0 volts. I have conducted this test but for some reason, regardless of adjustment on R6 the voltage on pin 6 remains constant at around 4.92 volts. Have you any idea what the problem may be? Thankyou

[GeoMax]

Hi,
have you checked for correct component placement? And have you inserted U2 the correct way? Or maybe you have got a fake Chinese component / IC from somewhere? Or maybe you have a short circuit with solder on the PCB. Have you checked on that too? Maybe you can upload detailed pictures of the top and bottom of the PCB? And maybe someone can spot the error somewhere on your PCB.