BARACUDA-Legend-1

[maikl]

Hello Friends,

No problem I think (but I can be wrong..) the 40106 is connectet to 5volts, -5 on pin 7 and ground to pin 14 ..

I think it is mistake to pin 14...

[6666]

I got into trouble with the prospecting forum moderator for posting there so I moved the discussion over here where it is more relevant.

Hi Grant what does that mean what trouble did you get into ?


I will pm you my info, no payment necessary
6666

[didier]

operating frequency of baracuda

Hello,

I have a question about the frequency baracuda works. I measured on my baracuda a periode of 1,6 msec or 625 Hz.
I checked the datasheet for ICL7660. Pin 7 of this IC is for frequency setting. When capacitor C16 sets the frequency, I have the question why in old schematics C 16 is 4700 pf and in the latest one it is 470 nF.
At what frequency is your baracuda working ?

Didier

[ApBerg]

I think it is mistake to pin 14...

Hello Maikl,

Yes, if you see the datasheet and look then at the baracuda circuit it looks not good... but as in the datasheet :

1. General description
The HEF40106B may be used for enhanced noise immunity or to “square up” slowly
changing waveforms.
It operates over a recommended VDD power supply range of 3 V to 15 V referenced to VSS......

In the baracuda Vdd (pin14) is connected to 0V (ground) and Vss (pin7) is connected to -5V ... this make's Vdd (pin14) +5V ....if referenced to Vss (pin 7)... This make's the 40106 very happy and it starts working...

But I agree with you it sure looks strance ! I also like to now way it is done that way.. so if anyone can explain ?

Best regards

Ap

[silverdog]

Just to let everyone know, Baracuda pcbs and kits are back in stock

It has been advised that as the SW1 function is unknown it is best to leave out Q5

Could someone confirm is the associated resistors should be left out as well or should the paths to ground around C14 remain by shorting Q5 source and drain ?

Silverdog

[ApBerg]

Just to let everyone know, Baracuda pcbs and kits are back in stock

It has been advised that as the SW1 function is unknown it is best to leave out Q5

Could someone confirm is the associated resistors should be left out as well or should the paths to ground around C14 remain by shorting Q5 source and drain ?

Silverdog

C14 470nF and R26 270k needs to stay

[gcause]

Hi Grant what does that mean what trouble did you get into ?


I will pm you my info, no payment necessary
6666

Thank you for that, I have PM'ed you back my info.

One of the moderators of the other prospecting forum posted a reply to my last message saying I should have sent it to you directly rather than posting it on that thread.

I didnt realise I was doing anything wrong at the time I posted it as others had done similar before me. However I then posted a message to that thread apologising for my post and explaining that I was just trying to get assistance with a problem related to the DIY Barracuda circuit.

I did notice that after that post both his post to me and my apology were removed from the thread the next day leaving only my original post. So I guess whoever it was may have had second thoughts on the subject.

In any case I thought rather than cause trouble it would be best to bring the discussion over to the GeoTech forum where DIY circuits are the primary focus.

Regards,

Grant

[gcause]

C14 470nF and R26 270k needs to stay

Hi ApBerg / Silverdog,

When you remove Q5 should the circuit still operate?

I removed it on one of my 2 Barracuda boards and the circuit failed to work from that point (no tone generated) until I put a solder bridge over the solderpads on the underside of the PCB where it had been.

I first tried soldering a bridge between the first two posts and this got the circuit to work again. This resulted in the original function of the circuit as if I had not removed Q5 it was generating a constant tone no matter what settings I tweaked.

I then undid this bridge and soldered a new bridge between the other two solderpads where Q5 had been. This allowed the circuit to work but changed the tone to a softer one but it still gave a constant tone.

In the end I just put a solder bridge across all three posts. Again constant tone however now when I tweak settings the tone goes up and down in volume but never goes off as others have suggested it should.

I have seen others say they just removed Q5 and the circuit works but that was not my experience.

I was orignally testing this without SW1 in place.

I then added SW1 and in all cases SW1 did make a difference to how the circuit operated.

SW1 appeared to change the tuning of the circuit as the tone changed, it got lower and I had to then change the settings for delay, offset to get it back to the original loud tone and Pin 6 U2 zero voltage increased slightly when SW1 was turned on. If I turned the SW1 off again I would again have to readjust settings to get back to my original tone and zero voltage on Pin 6 U2.

In all cases the circuit did not detect metal.

As I am a novice in electronics I will be sending my boards to 6666 to get someone with much more electronics experience to independently check my work and hopefully get these working.

Regards,

Grant

[ApBerg]

Hello Grand,

As you say that you have not much electronic now how...I wonder ... have you put the diode's on the board in the right way ? other than resistors there is only one way you can put them on the board, attention to the black band on the diode.

I think it is very nice from 6666 to look at your boards !

Best regards.

Ap

[porkluvr]

Hello Maikl,

... I agree with you it sure looks strance ! I also like to now way it is done that way.. so if anyone can explain ?
Best regards
Ap

The reason for using -5V and ground for the CD40106 is because swinging between ground and -5V, makes the sample JFETs happy. N-channel JFETS turn off with a negative voltage on the gate and turn on when the gate and source are at the same potential. The signal coming from the preamp is referenced to ground and if the gate drive signal were pulled to +5V it would swamp the relatively small ground referenced input signal.

If the sample FETs were replaced with CD4066, then the CD40106 would best be powered from -5V and +5V but since there are JFETS used instead, the sample pulses swing between -5V and ground.

That's a somewhat simplistic answer, I hope it get the important points across.

[maikl]

Hi ApBerg and porkluvr. Thank you for explanation. Probably the Mr.Jim Pugh (Anchor Electronics-Barracuda) had good reason to do just that. Best regards.

[maikl]

Hello,

I have a question about the frequency baracuda works. I measured on my baracuda a periode of 1,6 msec or 625 Hz.
I checked the datasheet for ICL7660. Pin 7 of this IC is for frequency setting. When capacitor C16 sets the frequency, I have the question why in old schematics C 16 is 4700 pf and in the latest one it is 470 nF.
At what frequency is your baracuda working ?

Didier

Hi dider. The frequency is 640 Hz. Not C16 than C10 = 4700pF = 4,7nF this is the old schematics and the new version of the same. Not 470nF.

[dfbowers]

C14 470nF and R26 270k needs to stay

I omitted these parts and the kit provided by Silverdog works fine.

Don

[gcause]

Hello Grand,

As you say that you have not much electronic now how...I wonder ... have you put the diode's on the board in the right way ? other than resistors there is only one way you can put them on the board, attention to the black band on the diode.

I think it is very nice from 6666 to look at your boards !

Best regards.

Ap

Hi ApBerg,

Yes I am a novice in electronics, its a hobby for me not my job. I also do gold prospecting as a hobby and I am combining both hobbies by building a metal detector.

I am keen to learn more from great forums like this one.

You can see my project here:

http://golddetecting.4umer.net/t6394...iy-pi-detector

I followed the silkscreens component layout noting where the band was and put the diodes in according to that. Band on the diode facing towards the band on the silkscreen.

For all components I followed the silkscreen layout.

It is very kind of 6666 to do this for me and I am very grateful to him.

Thank you for your assistance with this this it is greatly appreciated.

Regards,

Grant

[didier]

Baracuda operating frequency

Hello Maikl,

thanks a lot for answering my questions about the operating frequency of baracuda. Then everything works fine with my baracuda.

best regards,
Didier