Barracuda Legend Kit Problems

[Michaelo]

I'm getting similar detection distances to those posted in ivconik's last couple of posts but in other youtube videos the detection distances appear to be much greater...

I'm testing using Euro coins... I can detect 50 cent coins at about 6" but 2€ coins need to be at 4" or 5"... A small aluminium heatsink (1.5" x 1.5" x 0.5") can be detected at about 10" or more...

I test by suspending a string over the coil, attaching a coin and swinging it like a pendulum, that way I can try tweak the delay pot for best response...
Next test will be outside to see if I get any improvement but... can someone give me a reference to what I can expect so I know if my detector is up to scratch?

Mike

[ivconic]

I haven't watched those videos for quite some time.
Now watching them again i also notice another thing too; front end saturation and slow recovery, on iron pliers.

[ivconic]

Second video, no rejection:

[ivconic]

That is why I proposed some small standardized test coils be made available, maybe through Silverdog. If this was desirable what coils would we need? Maybe a 100mm in diameter 300uH, 450uH, others?

0.3mH - 0.5mH will do.
Sizes up to 10" are most "logical" for such project.
I tested few coils in that range.
If coil is later damped well; it works quite alright.
Randomly i make perfect coil with which later i achieve true rejection of some metals, of course when precisely adjust delay.
I never really recorded a video on that with Barracuda, but i recorded video with MPP showing exactly what kind of rejection it is.
First coin is Roman "Antoninianus" (bronze+Ag) and second one is CH Franc (Cu+Nickel).
It is obvious difference in response on those coins with delay on one position.
On second video there is no difference with delay on another position.

First video; rejection:

[Qiaozhi]

maybe through Silverdog
--
WHO is Silverdog? why always as a trouble there is poping-up the name silverdog?

Who you gonna call?

https://www.dogsnug.com/products/silver-widechest-dog-coat

[silverdog]

maybe through Silverdog
--
WHO is Silverdog? why always as a trouble there is poping-up the name silverdog?

[Old cart]

[QUOTE=Polymer;215338]Hi Old cart,

This might be the list you are looking for. I found it accidentaly whilst I got "lost" clicking around on this site ...

http://www.geotech1.com/cgi-bin/pages/common/index.pl?page=metdet&file=info/coils/index.dat

I know I have a very comprehensive coil parameter list from this site on hard disk, It'll take a bit to find it, but I will post once found ...

That is what I remember, thank you very much!

[Polymer]

Hi Old cart,

This might be the list you are looking for. I found it accidentaly whilst I got "lost" clicking around on this site ...

http://www.geotech1.com/cgi-bin/pages/common/index.pl?page=metdet&file=info/coils/index.dat

I know I have a very comprehensive coil parameter list from this site on hard disk, It'll take a bit to find it, but I will post once found ...

Cheerio

[Old cart]

KEEP THOSE TABLES ANYWHERE. i give them again and again and again. i gave them 10th times.
you dont need a calculator and calculate
[ATTACH]35652[/ATTACH][ATTACH]35651[/ATTACH]

Sorry KT, I have never seen those tables, and I spend a lot of time on this forum.
But that is not exactly what I was looking for. I think it is a table that you published that showed the L and R of coils listed by the name of the detector they go with. I can not find it now. As we say in America- I have my **** together, I just can not lift it! ( I do not know if that wil translate well)

Silverdog is the guy who has a web site that sells detector kits like Chance, Baracuda, Surf PI, Minipulse, and others. Google Silverdog and you will see!

[kt315]

KEEP THOSE TABLES ANYWHERE. i give them again and again and again. i gave them 10th times.
you dont need a calculator and calculate

[kt315]

maybe through Silverdog
--
WHO is Silverdog? why always as a trouble there is poping-up the name silverdog?

[Old cart]

"...166uH..." !!

That explains a lot.

That is why I proposed some small standardized test coils be made available, maybe through Silverdog. If this was desirable what coils would we need? Maybe a 100mm in diameter 300uH, 450uH, others?

[ivconic]

In actual fact, the soldering iron is often in use here. I regularly use a combination of hand calculations, simulations and real hardware.. You really do need to be proficient in all areas to achieve good results.

I have the Baracuda here, and gave it a cursory glance a few nights ago. The unit was very unstable and with poor detection depth. The first thing I noticed was that the MOSFET was very hot, so I detached the coil and found it to be 166uH which is far too low, and the reason for the excess heat. Power supplies were all in the correct range, but the TX oscillator output was distorted and the main sample pulse was false triggering and giving two separate pulses. During further testing the CD40106 went kaput, with the result that the -5V supply was being pulled down to -3.84V. Literally, a few minutes ago. the postman arrived with a bag of parts including the CD40106 replacement. However, there's Bank Holiday weekend imminent here in the UK, and I have guests coming to stay. Hopefully I can get another look at the Baracuda some time next week, as long as real work doesn't get in the way.

"...166uH..." !!

That explains a lot.

[Qiaozhi]

No heat yet?
Any discoveries on that faulty Barra?

In actual fact, the soldering iron is often in use here. I regularly use a combination of hand calculations, simulations and real hardware.. You really do need to be proficient in all areas to achieve good results.

I have the Baracuda here, and gave it a cursory glance a few nights ago. The unit was very unstable and with poor detection depth. The first thing I noticed was that the MOSFET was very hot, so I detached the coil and found it to be 166uH which is far too low, and the reason for the excess heat. Power supplies were all in the correct range, but the TX oscillator output was distorted and the main sample pulse was false triggering and giving two separate pulses. During further testing the CD40106 went kaput, with the result that the -5V supply was being pulled down to -3.84V. Literally, a few minutes ago. the postman arrived with a bag of parts including the CD40106 replacement. However, there's Bank Holiday weekend imminent here in the UK, and I have guests coming to stay. Hopefully I can get another look at the Baracuda some time next week, as long as real work doesn't get in the way.

[ivconic]

No heat yet?
Any discoveries on that faulty Barra?