BARACUDA-Legend-1

[wizz737]

Hi 6666, I ordered a 40106 for my bara today. tried replacing the 7660a but still have less than -3volts with poor sensitivity. sounds like you were experiencing the same problem. Hope replacing the 40106 clears up my problem.

Vermeer111, Congrats on your mods to the bara excellent work I hope I can get mine working as good.


best regards,

[Vermeer111]

"build mono fast coils" was not regsniff the autor was bbsailor excuse me

[6666]

Just a note on the -5 volt output

on one of the barracuda boards i fixed , it had a low output of about -3 volts with the rest of the chips plugged in, turned out to be a faulty 40106, changed it and it works nicely

[Vermeer111]

i make pictures tomorrow i had 3 different coils 6" 8" and 11" not coplanar normal monocoil build as a fastcoil (i think regsniff made a wonderfull pdf)shielded with 3m 24 material (by the way a wonderfull material for shielding) my cable (when i am finish) is rg58 grettings from the harz mountains

[bernte_one]

hello vermeer

can you post a picture of your coil

my last is here

http://www.geotech1.com/forums/showpost.php?p=143404&postcount=18

with vacuum formed coil shell

if you need one ask

regards bernd

[Vermeer111]

yeahh barracuda rules.have winding a new coil 11"and have change the 412 with the tl082 and now i have first "reaction" in 35-38 cm for a 1 euro coin the same for a small goldring,a Ball from gold (for a necklace)weight under 1 gramms (the kitchenscale begins at 1 Gramms and have no reactions) have in 5-8 cm.i think its all ok with my barra.all measures with shielded coil without shielded cable on my bench in my home.next step is the lt1115 for the 5534 "mod" grettings from the harz montains

[Qiaozhi]

I don't have a Baracuda to look at but from looking at the RE schematic (from I don't know who) the 7660 pin-8 input and 78L05 input are both connected to the B+.

?? The Barracuda's 7660 has his + in from the batt's/power supplay ...that way care must be taken for the batt/power supllay ...not more than 12 volts !! higher voltage's are not healty for the 7660 !

For the surfmaster is Qiaozhi's explaining OK.

Interesting ... the schematic I was looking at is labelled "Barracuda PI", but on closer examination it's obviously a Surf PI.

You can see that the designer of the Barracuda must have also spotted the same problem with the power supply. In that case, try applying this mod to the Surf and see what happens.

[ApBerg]

i Have a question can i build a Dual Coil like Surf Pi Dual Coil for the Barracuda.
I think 12" and 6".
Normaly you have 450uH,with Dual Coil every single Coil has 225uH is this right.
And what is the Pro and Contra for a Dual Coil and a Mono Coil
Thank you greetings from the Harz Montains

The Barracuda is very tolerant for coils, so give it a tray!
For every coil you make check the delay settings.

Succes.

Ap,
..........from the Dutch lowlands..

[Vermeer111]

i Have a question can i build a Dual Coil like Surf Pi Dual Coil for the Barracuda.
I think 12" and 6".
Normaly you have 450uH,with Dual Coil every single Coil has 225uH is this right.
And what is the Pro and Contra for a Dual Coil and a Mono Coil
Thank you greetings from the Harz Montains

[wizz737]

Help power supply problem

Hi all, Thank you for fast reply. The 7660 in my bara is a 7660SCAPZ which I think is the same as the 7660A for 13v input. I have to head off to work now but will do more testing tonight when I get home and post results.


Many thanks

wizz737

[ApBerg]

In the Barracuda circuit, the 7660 voltage converter is powered from a 78L05, which means the negative voltage at pin 5 will not be -5V as shown in the schematic. This voltage is always lower than expected. You could improve this circuit by breaking the track that goes between the 78L05 output and pin8 of the 7660, and connecting the 7660's input directly to the +ve side of the battery. In this case you must use a 7660A, as the 7660 has a maximum input voltage of 10V. Also, the 7660 is synchronized to the TX oscillator via pin 2. Since the TX pulse rate is relatively low for the 7660 to operate efficiently, this will also cause the -5V supply to drop out when the input voltage is lowered.

?? The Barracuda's 7660 has his + in from the batt's/power supplay ...that way care must be taken for the batt/power supllay ...not more than 12 volts !! higher voltage's are not healty for the 7660 !

For the surfmaster is Qiaozhi's explaining OK.

ok.. close finish... but Porklovr was first...

[porkluvr]

In the Barracuda circuit, the 7660 voltage converter is powered from a 78L05, which means the negative voltage at pin 5 will not be -5V as shown in the schematic. This voltage is always lower than expected. You could improve this circuit by breaking the track that goes between the 78L05 output and pin8 of the 7660, and connecting the 7660's input directly to the +ve side of the battery. In this case you must use a 7660A, as the 7660 has a maximum input voltage of 10V. Also, the 7660 is synchronized to the TX oscillator via pin 2. Since the TX pulse rate is relatively low for the 7660 to operate efficiently, this will also cause the -5V supply to drop out when the input voltage is lowered.

I've got to disagree with you on that, Qiaozhi. I don't have a Baracuda to look at but from looking at the RE schematic (from I don't know who) the 7660 pin-8 input and 78L05 input are both connected to the B+.

Alexismex's hand drawn schematic also shows 78L05 and ICL7660 inputs connected, to what must be B+.

If there were less than -5V being outputted from the 7660, there would be no need to have a 79L05 in the circuit because it would not work.

[Vermeer111]

yes the 7660 in my kit was faulty,new 7660 and the "Legend" was running no big problem

[Qiaozhi]

Hi Folks, my bara has developed a power supply problem. with a 10.8v supply the -5 volt regulator 79l05 has around -2.5v on output pin,the positive regulator 78l05 is +5v. If I lower the supply voltage to around 9volt the bara will work but with low sensitivity and the -5 will come up to -3.5v. I tried changing out the 79l05 but no change. I'm thinking maybe the 7660 is defective. any thoughts would be appreciated.

In the Barracuda circuit, the 7660 voltage converter is powered from a 78L05, which means the negative voltage at pin 5 will not be -5V as shown in the schematic. This voltage is always lower than expected. You could improve this circuit by breaking the track that goes between the 78L05 output and pin8 of the 7660, and connecting the 7660's input directly to the +ve side of the battery. In this case you must use a 7660A, as the 7660 has a maximum input voltage of 10V. Also, the 7660 is synchronized to the TX oscillator via pin 2. Since the TX pulse rate is relatively low for the 7660 to operate efficiently, this will also cause the -5V supply to drop out when the input voltage is lowered.

[porkluvr]

Why don't you check the output voltage of the 7660 (input to 7905)?

If you replace the ICL7660 I suggest you use the 'A' version, ICL7660A.