BARACUDA-Legend-1

[maikl]

G'day,

The only mod done was the LM4562 that replaced the LM412. The unit plugs into the headphone socket on the control box and the external speaker plugs into the audio amp - have attached photo's of how it looks and the schematic. Now I really love the bara as a beach detector - to give you an idea of depth performance, I dug out a $2 coin at approx. 30cm and a 20 cent coin at approx. 35cm at Dromana beach.

Excellent done Finderskeepers

[andrew]

Andrew.

I had that problem. It may not be the Baracuda at all. There is a good possibility that there is a source of noise nearby. Try taking the Baracuda to another location and see of you have the same results.

Don

High dbflowers! i tried outside but no difference but... i think we have found the problem all along? the 2m2 resistor was not letting a lot of the signal through and sometimes loading the oscillator down from the 7660 (if you have the threshold up fully this makes the beep beep and no detection) so ive bridged it with a 2k resistor and all seams well for now! any reason why such a high value of resistor was used? 2m2 seams a little high? cheers andrew..

[wallker]

G'day,

The only mod done was the LM4562 that replaced the LM412. The unit plugs into the headphone socket on the control box and the external speaker plugs into the audio amp - have attached photo's of how it looks and the schematic. Now I really love the bara as a beach detector - to give you an idea of depth performance, I dug out a $2 coin at approx. 30cm and a 20 cent coin at approx. 35cm at Dromana beach.

Hi Finderskeepers,
What sensitivity did you have before this mod?
I'm asking this cause my cuda have similar sensitivity with no mod at all.
Regards Marko.

[dfbowers]

Oh what joy lol everything going well built the stem all boxed up, put together, then i pick it up and it wont have it goes in to its beep beep and detect nothing? put it down threshold comes back and it detects! lol i took the bottom stem off and its all ok until i move the head side to side? any ideas anyone

Andrew.

I had that problem. It may not be the Baracuda at all. There is a good possibility that there is a source of noise nearby. Try taking the Baracuda to another location and see of you have the same results.

Don

[andrew]

Oh what joy lol everything going well built the stem all boxed up, put together, then i pick it up and it wont have it goes in to its beep beep and detect nothing? put it down threshold comes back and it detects! lol i took the bottom stem off and its all ok until i move the head side to side? any ideas anyone

[andrew]

Hi Andrew,

Glad to hear you have better performance now. Not sure about using 2 mosfets, If you mean in parrallel then the turn on voltage of each mosfet will be slightly different and stagger the current flowing through the coil - this might produce some wierd results!

Are you using the TIP127? If so you might like to try the IRF9640, I've found it runs a little cooler, or you could try and limit your supply to 12v. I used to use a 12v regulator to limit a 14.4v rechargeable battery pack that ran my surf PI - it worked OK!

Look forward to hearing how you get on at the beach

Cheers, Jim.

Hi jim, i am using a irf9530 i found in my bits n pieces draw as the 9640 i got from silverdog was shorted,it seams to be doing the job as well going by posts of people who have built the baracuda as regards depths/sensitivity! its the same pn junction and pinouts but is rated at 75watts max dissipated instead of the 9640's 125watts, i may try building a little board with 2 mosfets in parallel and see what happens like you say it may throw up a few weird surprises? i am using 8aa for the 12v and around 2500 mah so should give me 20hrs detecting? cheers andrew..
ps. gave up on the 12v 6amp lead acid battery as its had it and would not take a charge!

[Finderskeepers]

Marko look here, re damping

http://www.geotech1.com/forums/showpost.php?p=122955&postcount=373

Finders thats interesting about the amp
what mods did you do to the audio cct on the board

G'day,

The only mod done was the LM4562 that replaced the LM412. The unit plugs into the headphone socket on the control box and the external speaker plugs into the audio amp - have attached photo's of how it looks and the schematic. Now I really love the bara as a beach detector - to give you an idea of depth performance, I dug out a $2 coin at approx. 30cm and a 20 cent coin at approx. 35cm at Dromana beach.

[TH Jim]

Hi Andrew,

Glad to hear you have better performance now. Not sure about using 2 mosfets, If you mean in parrallel then the turn on voltage of each mosfet will be slightly different and stagger the current flowing through the coil - this might produce some wierd results!

Are you using the TIP127? If so you might like to try the IRF9640, I've found it runs a little cooler, or you could try and limit your supply to 12v. I used to use a 12v regulator to limit a 14.4v rechargeable battery pack that ran my surf PI - it worked OK!

Look forward to hearing how you get on at the beach

Cheers, Jim.

[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.

I think we are ok porkluvr! as the ground connection is for vss on the 40106

[wallker]

Thanks 6666.
Marko.

[6666]

Marko look here, re damping

http://www.geotech1.com/forums/showpost.php?p=122955&postcount=373

Finders thats interesting about the amp
what mods did you do to the audio cct on the board

[andrew]

Hi Andrew,

Yes I know what you mean! It is so much more rewarding to build your own detector than buy a ready made one. BTW the power supply for the Baracuda - like the SurfPI is 12v. It will not work well or for very long on a 9v PP3. Your lead acid battery sounds like a good choice! Hope this helps

Regards, Jim.

yes indeed jim ive learnt a lot building the cuda and thanks for the tip yeh pp3 like you say cant provide the amps! i stuck it on a 7 amp regulated psu and wow! what a difference, mosfet ran a little hot stuck ammeter in line at 13.8v it was drawing 120ma. was wondering about using 2 mosfets in parallel for a bit more output? anyway got it in a box and wired up coil is done just gotta compound it! and finish stem and we will be away down the beach for a test! then its on to the more complicated tgsl next cheers andrew..

[TH Jim]

Hi Andrew,

Yes I know what you mean! It is so much more rewarding to build your own detector than buy a ready made one. BTW the power supply for the Baracuda - like the SurfPI is 12v. It will not work well or for very long on a 9v PP3. Your lead acid battery sounds like a good choice! Hope this helps

Regards, Jim.

[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.

[wallker]

Damping resistor

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