BARACUDA-Legend-1

[nelson]

Barracuda problem

Hi

I just finish my second barracuda from Silverdog kit.
The detector is working fine, but some times it start to doing some beep beeps beeps.
I re adjusted inside pots, coil and cable and first time seems that was the coil wich i replaced for another one with 50 ohms coaxial cable. After this all returns to normal after i had the idea to paint my coil has i always do. First try was fantastic, but next day after 5 or 10 minutos of work the beeps beeps return. Then i checked my lead acid 12 V 1.2 A battery and i measure 11.6 volts. So to make shure the problem it was not the battery, i charged fully. THen i try the detector on the filed for about two hours and no problem at all.
I know this looks that the problem ws finally my battery, but the person who uses this detector had this beep beep problem, re charged the battery and the problem persist. I change the coil and it was fixed until i got the problem again till i re charge the battery.
My concern now is if this could happend again after more use or is really a problem with the baterry.
Any ideas?
In advance many thanks
Nelson

[andrew]

help with 40106 voltage check!

Having finnished building the baracuda board i am not having much success with it at the mo, i suspect the 40106? here are the voltages i am getting with it installed and without!

installed

pin 1= .63v
2= -5v
3= .63v
4= -5v
5= .58
6= -5v
7= -5v
8= -4.8v
9= -.3v
10= -.3v
11= -3.7
12= -5v
13= 0v
14= 0v

uninstalled

1= 5v
2= 0v
3= 5v
4= 0v
5= 5v
6= 0v
7= -5v
8= 0v
9= 0v
10= 0v
11= 0v
12= 0v
13= 0v
14= 0v

i am getting intermittent freshold tone, and i have found by putting the test probe off my voltmeter on pin 11 i do get some detection with metal and my hand the same? but not very sensitive! anyway if anyone can help i would be most grateful many thanks andrew........

[porkluvr]

What do you measure at the output of the +5V regulator? You should measure the same at U1-14.

Yours sounds like an open trace or bad solder between 78L05 output and 40106 pin-14.

[andrew]

What do you measure at the output of the +5V regulator? You should measure the same at U1-14.

Yours sounds like an open trace or bad solder between 78L05 output and 40106 pin-14.

Hi porkluvr! many thanks for replying pin 14 is tied to ground on my pcb? pin 1 as the 5v from the 78l05 and checks ok! but when i put the 40106 back in it decks the the 5v on pin 1 down to .6v so thinking a short or very low resistance between 1-14 inside the chip? what do you think? cheers andrew...

ps going on pinout from here! http://www.nxp.com/documents/data_sheet/HEF40106B.pdf

[porkluvr]

pin 1 as the 5v from the 78l05 and checks ok! but when i put the 40106 back in it decks the the 5v on pin 1 down to .6v so thinking a short or very low resistance between 1-14 inside the chip? what do you think? cheers andrew...

Very possibly as you say, shorted internally.

But you should remove the 40106 and check resistance of all those pins to the 78L05-1, to make sure there are no shorts.

You were right, pin-14 should be ground and I've been corrected on that before. (I'll fix my schematic for sure, this time.)

Hmmm, as I look this over some more... I see a problem with the design, or should I say the RE of this machine. My CD40106 datasheet (from Fairchild) states that input pins should only be pulled as high as 0.5V above Vdd. That means only 0.5V above ground, yet I think I see that some of the schmitt trigger timing resistors from inputs go to +5V. That's a no-no. I'll have to do some more perusal to make sure of what I'm seeing.

All I can say is make sure the resistors are not the wrong values, and if I were to build Baracuda I would want to make the timing resistors go to ground instead of pulling them to +5V.

I've got to go. I'll look at this some more when I get back.

[andrew]

Very possibly as you say, shorted internally.

But you should remove the 40106 and check resistance of all those pins to the 78L05-1, to make sure there are no shorts.

You were right, pin-14 should be ground and I've been corrected on that before. (I'll fix my schematic for sure, this time.)

Hmmm, as I look this over some more... I see a problem with the design, or should I say the RE of this machine. My CD40106 datasheet (from Fairchild) states that input pins should only be pulled as high as 0.5V above Vdd. That means only 0.5V above ground, yet I think I see that some of the schmitt trigger timing resistors from inputs go to +5V. That's a no-no. I'll have to do some more perusal to make sure of what I'm seeing.

All I can say is make sure the resistors are not the wrong values, and if I were to build Baracuda I would want to make the timing resistors go to ground instead of pulling them to +5V.

I've got to go. I'll look at this some more when I get back.

Well seem to have got some life out it now? played around with the timing preset and the other trimmer to the 553, stable now but only picking up a 10 x 8cm tobacco tin about 10cm
best i can get it with a 19cm 30 turns coil out of speaker cable the fet is not getting hot either!

[porkluvr]

So, your +5V supply is working now? If your 40106 caused it to load down bad enough to go into over-current protection, the 40106 may be damaged and you should replace it.

They can be damaged and still work but not working right, and it won't get any better over time.

[andrew]

So, your +5V supply is working now? If your 40106 caused it to load down bad enough to go into over-current protection, the 40106 may be damaged and you should replace it.

They can be damaged and still work but not working right, and it won't get any better over time.

Thanks porkluvr for your help, ive ordered some 40106's so will try them when they come! i can get the sensitive up quite a bit by connecting a voltmeter to minus side of coil and + lead to the op amp pin 6 that goes to the 2m2 resistor strange? then while connected i can set the threshold to get good depth? crazy cheers andrew.

[andrew]

Thanks porkluvr for your help, ive ordered some 40106's so will try them when they come! i can get the sensitive up quite a bit by connecting a voltmeter to minus side of coil and + lead to the op amp pin 6 that goes to the 2m2 resistor strange? then while connected i can set the threshold to get good depth? crazy cheers andrew.

Got the cuda up and running how it should with respectable detection depths! It seams there was little wrong with the pcb or components! and all along the problem was electrical interference in my and probably my neighbours apartments, i have forgotten the amount of electrical trash the average houshold must emit nowadays from pc's wireless and applications like plt pla's etc as well as plasma tv etc etc and of course, metal detectors like the baracuda are very sensitive things especially unshielded pcb's open on the kitchen table lol, i have seen lots of posts of people having problems setting up projects on here and i bet a lot are down to this!

[TH Jim]

If it helps anyone I have a ready made, tested and working Baracuda board for sale in the "Buy/sell/trade" forum. Jim

[bernte_one]

hello jim

still the same one you want to sell?

i think you should reduce price max 150 us dollar for complete unit
i had also no luck on german forum no one wants to buy my surfmaster pi electro unit offered for 60 euro fully mounted but without coil and shaft

i think greatest problem is that no one trust us

if i had no luck to build baracuda anf if i were a rookie in electro skills
i would buy baracude from you

i know it good performance

nice evening and good luck

[TH Jim]

Hi Bernte,

Yes I still have the same Baracuda for sale

I can understand people might not believe that a home built detector can be as good as a commercial unit and not want to risk paying a lot of money for one, but you and I and some of the other guys on here know they can be just as good if they are made well

I thought I would get more interest if I sold just the PCB - especially as it is not much money and only slightly more expensive than a new kit.

We will have to be patient i think

Good luck with your SP

Cheers, Jim.

[andrew]

If it helps anyone I have a ready made, tested and working Baracuda board for sale in the "Buy/sell/trade" forum. Jim

Tempted thanks jim but defeat's the object so to speak! i think pp9 battery is a lot of the problems not enough current capacity! just charging up a 12v 6amp lead acid that should do it hopefully? cheers andrew.

[wallker]

Damping resistor

Can someone post osci. picture of U2 (NE5534) pin6 with adjusted damping resistor?
Regards Marko.

[Finderskeepers]

audio improvement

Hello all,

Try replacing the lm412 with a lm4562 and you will notice a smoother threshold.

I have just completed a simple audio amplifier using a tda2003 and now obtain approx. 20% increase in depth. It's connected to an external 8ohm/5watt speaker and powered with 9volt/200mah ni-mh batt. The unit is enclosed in its own box and attached to the control box of my bara. It makes those very soft subtle tones more audiable and now get a ring at 36cm and a 5 cent aust. coin at 30cm with a minelab 11 inch monocoil.