baracuda setup procedeure?

[rabbit]

hi all,

Built a baracuda kit from silverdog, must say excellent board and kit. got it up and running first go!, detected gold bracelet at 50cms! but a lot of tone from the speaker to keep it sensitive, when i turn down threshold to less or no noise it detects 1/3 of the distance. is there some setup procedeure so it makes no or little noise and detects further?

somewhere i read to get the 5534 pin 6 to 0 volts, is that correct? if so where to adjust?

also can get a scope, but where to connect it and what to look for, and how to tweak?

Thanks in Advance
Rabbit

[johnandles]

hi all,

Built a baracuda kit from silverdog, must say excellent board and kit. got it up and running first go!, detected gold bracelet at 50cms! but a lot of tone from the speaker to keep it sensitive, when i turn down threshold to less or no noise it detects 1/3 of the distance. is there some setup procedeure so it makes no or little noise and detects further?

somewhere i read to get the 5534 pin 6 to 0 volts, is that correct? if so where to adjust?

also can get a scope, but where to connect it and what to look for, and how to tweak?

Thanks in Advance
Rabbit

I have seen this post go unanswered ..
So all I can suggest is do a search of whatever you are trying to find.
There is a lot of info on this site, be like a rabbit,rabbit and dig and sniff..you will find it!
cheers
John

[porkluvr]

hi all,

Built a baracuda kit from silverdog, must say excellent board and kit. got it up and running first go!, detected gold bracelet at 50cms! but a lot of tone from the speaker to keep it sensitive, when i turn down threshold to less or no noise it detects 1/3 of the distance. is there some setup procedeure so it makes no or little noise and detects further?

somewhere i read to get the 5534 pin 6 to 0 volts, is that correct? if so where to adjust?

also can get a scope, but where to connect it and what to look for, and how to tweak?

Thanks in Advance
Rabbit

To set your offset null you adjust the trimpot connected to pins 1 and 8 on the 5534. Check offset with your scope probe at the U2 output (U2-6). I think zero volts is good.

I might have some ideas about your sensitivity issue but before I would say anything I want to know, what is the actual part number of the FETs you have at Q3 and Q4?

[rabbit]

thanks so much for your reply, my fets are standard silverdog issue, 2N5485 & MPF102, is that ok?
cheers
Rabbit

[bernte_one]

hello rabbit
with the parts from silverdog the units should work
the setup procedure you read often here was made for the ideal (or original coil) i think
if you dont hit the coils specs wich are suggested you cant setup the offset to zero volt and think all should work fine then
i do it this way:
i make a coil for example 24turns of 0,5mm yv wire, 27cm diameter
schould be under 2R and 400uH
threshold at nine o´clock
delay at 12 o´clock
(if you have pots connected for both)

offset is in middle position (i dont use multiturn trimmer i use an ordinary pcb trimmer)
then turn offset down and watch result - mark best postion on srew from trimmer
then turn trimmer up and see if you can get a better result as before, if yes you are right there

at the end you can make a chekc and measure ne5534 and lokk the offset voltage
in my case it is not zero volt but often it is near a critical border before the voltage doesn´t change anymore when turning the offset trimmer

with light humming threshold and delay between 9 and 12o´clock i got a 2€ coin easy at 30cm in air
and i think all about this distance +/- 2cm are godd enough for such a simple machine

head up, i hope i could help
kind regards

[peter morgan]

hi there peeps I have got my Baracuda legend up and running. Iam using a coil of 9" 26turns of the wire which has a ohms reading of 2.4, it detects pennys steel and iron but not what I built it for gold? it detects platinum but its got to touch the coil to give a beep I am totally confused is there anyone who can help me out as to why this is thanks for peter.

[satdaveuk]

hi there peeps I have got my Baracuda legend up and running. Iam using a coil of 9" 26turns of the wire which has a ohms reading of 2.4, it detects pennys steel and iron but not what I built it for gold? it detects platinum but its got to touch the coil to give a beep I am totally confused is there anyone who can help me out as to why this is thanks for peter.

Hi
I don't know what version Barracuda you built but would put my money on that your coil is to far out of spec, with a 8" coil you certainly need to be under 2ohms near to 1.5ohms as possible but not under and a inductance of near to 453uH as possible as Bernte stated .
However what I did find was that with 1.5" coil the optimum was just over 2ohms and induction around the 500uH mark, so coil sizes will need a small but very significant change in specfication for optimum performance which if you note is probably why Bernte had good results with his build together with the larger coil
Once you have those coil parameters then again as Bernte stated go for the 0V with off set preset but only as a starting point.
After that before doing anything else I personally set the damping resistance up with a scope and then follow procedure as above.
Far as gold detection that is one of many things that makes the Barracuda shine above many other PI designs , it simply loves the stuff when built to Anchor spec.
Let us know how you get on
Regards