How do I tune a Baracuda PI?

[grizzly]

I have a Baracuda PI that I built from a Silverdog kit. I am having trouble getting it to preform as expected. It does work but has limited range about 5" on a quarter with an 8" coil. Is there a technique to tuning the detector correctly. I have an oscilloscope, and a multimeter. I dont have any experience using the oscilloscope. thanks.

[WM6]

I have a Baracuda PI that I built from a Silverdog kit. I am having trouble getting it to preform as expected. It does work but has limited range about 5" on a quarter with an 8" coil. Is there a technique to tuning the detector correctly. I have an oscilloscope, and a multimeter. I dont have any experience using the oscilloscope. thanks.

Probably you need to read this Reg Sniff article (about damping resistor especially) first:

http://www.nuggetshooter.com/article...Idetector.html

and then adopt your coil to your Baracuda circuit by set proper value of damping resistor. If you use scope fall of back EMF have to be as much like as on figure bottom left (by proper setting of damping R):

http://174.132.129.189/~moreland/forums/showpost.php?p=123514&postcount=7

[bernte_one]

I have a Baracuda PI that I built from a Silverdog kit. I am having trouble getting it to preform as expected. It does work but has limited range about 5" on a quarter with an 8" coil. Is there a technique to tuning the detector correctly. I have an oscilloscope, and a multimeter. I dont have any experience using the oscilloscope. thanks.

at first you can set offset by measure with multimeter
connect coil to detector and switch on
black probe to gnd(-) and red probe to pin 6 from ne5534 set offset to nearly 0volt or zero (same as surf pi and surf pi pro)

then you can adjust delay and threshold with your feeling wipe metal object over coil and set to best range

regards

[grizzly]

Thanks for the info. Now I just need to figure out how to use my O-scope.

[jap]

Hi grizzly
Why make it difficult and you have easier to follow what bernte one said.
best time
j.

[WM6]

Thanks for the info. Now I just need to figure out how to use my O-scope.

Here some basics:

http://www.best-microcontroller-proj...illoscope.html

[grizzly]

ive tried the pin 6 to 0 technique and am not getting god results. I may need to work on my coil more. Perhaps a damping resistor will help. Do I put the resistor across the leads from the coil?

[sinclairuser]

i have just built the barracuda too
for starters dont bother with damping resistor if your coil is 450uh and 1.5 ohms resistance the bernte one method works perfect
the secret is the delay adjusting use the purest gold you can get 9 14 18ct gave poor results for me satdaveuk speculated that my barra was detecting the copper in the low carat gold when i set the detector up with my block of bullion gold leaf it was better but it still only detects to 6-7 ins (any metal)
from reading reviews of the original barra it never detected much beyond that depth anyway to be honest in soil anyway
afterall it is a reverse engineered early 90s design some people claim 12 inces in air but thats meaningless its soil that counts
what i mean about the scope is you say you dont know how to use it so dont bernte ones method works perfect as for the damping resistor its r1 onthe board and is 330 in the kit which is right for the coil specs above
what im saying is if you dont know how to use a scope you can do more harm than good by playing with the dampener!
thanks ally x

[satdaveuk]

Hi
got everything populated as the original lay files, just waiting for the 25k multiturn presets.
Far as coil if its raining on sunday may quickly do the cat5e 4 turnes and series the pairs as stated and check results.
I was thinking maybe later using the cat5e again but striping apart and use one core to give the barracuda spec of 450 micro henrys at 105 ohms.
Has anybody tryed that and if so was there any advantage doing so with this project.
Regards
Dave

[satdaveuk]

i have just built the barracuda too
for starters dont bother with damping resistor if your coil is 450uh and 1.5 ohms resistance the bernte one method works perfect
the secret is the delay adjusting use the purest gold you can get 9 14 18ct gave poor results for me satdaveuk speculated that my barra was detecting the copper in the low carat gold when i set the detector up with my block of bullion gold leaf it was better but it still only detects to 6-7 ins (any metal)
from reading reviews of the original barra it never detected much beyond that depth anyway to be honest in soil anyway
afterall it is a reverse engineered early 90s design some people claim 12 inces in air but thats meaningless its soil that counts
what i mean about the scope is you say you dont know how to use it so dont bernte ones method works perfect as for the damping resistor its r1 onthe board and is 330 in the kit which is right for the coil specs above
what im saying is if you dont know how to use a scope you can do more harm than good by playing with the dampener!
thanks ally x

Hi Ally
I didnt speculate because its a fact, the only way to know if your actually detecting gold is to have in your possesion pure gold ie gold nuggets.
I havent so the nearest i can get to that is 18ct.
Gold leaf on a cup or plate means nothing because none of us know how pure the gold is and whats in the make up of the pot.
If you notice on various tests done not with just the Barracuda but many others, the gold detection is inconsistant the reason for that is many varibals, oviously build spec but also the type and content of the gold under test.
We are lucky in the Uk because are gold is normally stamped with how much purity it contains although the other metals its mixed with and amounts is not logged,however alot of countrys do not have that such as Indian gold.
Quite often a gold ring for instance thats detected in the field is not located due to its gold content but due to the crap that was mixed with it.
I only comment on personal experience after doing years of field tests, the theory behind all that I leave to the clever guys on here.
Such a instance my minipulse 3, even with that bog standard rushed together 6" coil made out of standard security alarm cable detected very loud and clear at 9", when I say loud and clear I mean screaming.
Fine now we know that it detects in air, hall marked mans wedding ring at 9" inches easy, Dont think for one miniute its detecting the gold because theres so many people on here who have access to near pure gold with various projects that are talking about 3-4" if there lucky some even less.
Now im quite happy that it detects 18ct gold in air 9" because that means with a bit of luck would pull from real ground at about 6-7" and considering the size of the coil and the way it was built isnt bad.

Regards

Dave

[satdaveuk]

Hi
got everything populated as the original lay files, just waiting for the 25k multiturn presets.
Far as coil if its raining on sunday may quickly do the cat5e 4 turnes and series the pairs as stated and check results.
I was thinking maybe later using the cat5e again but striping apart and use one core to give the barracuda spec of 450 micro henrys at 1.5 ohms.
Has anybody tryed that and if so was there any advantage doing so with this project.
Regards
Dave

I ment 1.5 ohms