Barracuda Legend Kit Problems

[6666]

[QUOTE=Qiaozhi;214953 Clearly, several people have already built this design and claim that it works, .[/QUOTE]

One that I repaired

https://www.youtube.com/watch?v=sqMtzIPxv9I

21 seconds of my own home made Bara working

https://www.youtube.com/watch?v=7b47WYDqwdw

[darkfibre]

That shield is a bit over the top, maybe you should do some tests with it removed.

[Impulse]

Does your shield have a gap in it so there is not a complete ring or closed loop around the coil? What kind of shielding are you using? As for wire that should be fine. It may not be as fast as more exotic solutions but it should be fast enough since coil speed is primarily driven by interwinding capacitance which is primarily determined by the spacing between each turn of the winding and also by the spacing between each turn and the shield. In your case you might try to layer two layers of the spiral wrap around the coil and apply the shield on the a outside of that being very careful to leave a gap of maybe 8mm between the ends of the shield.
Did you ever try the single shorted loop of wire experiment I described earlier?

Hi Old Cart i have used this for a shield and there is a gap of 20mm i have soldered a piece of stripped 0.5mm enameled wire to the shield and it is connected to the neg of the coax cable. and there isnt much (if any) gap between each turn as the spiral wrap holds the coils tight together so this is probably the main cause of the slow coil. i will order the new cable from china and try another once it arrives with a double layer of spiral wrap and PTFE tape.

http://uk.rs-online.com/web/p/cable-sleeves/0239078/?searchTerm=shielding+mesh&relevancy-data=636F3D3126696E3D4931384E4C446573635461786F6E6F6D794272616E645365617263685465726D266C753D656E266D6D3D6D617463687061727469616C6D617826706D3D5E5B5C707B4C7D2D5C707B5A737D5D2B2426706F3D353426736E3D592673743D4B4559574F52445F4D554C54495F414C5048412673633D592677633D4E4F4E45267573743D736869656C64696E67206D657368267374613D736869656C64696E67206D65736826

[Qiaozhi]

Can someone please probe pin8 of the 40106 with a scope on channel 1, and then pins 12, 6, 4 and 2 respectively, so that we can see the relationship between the TX oscillator output (pin 8 ) and each of these signals.

I can see that running the 40106 between 0V and -5V will drive the TX stage correctly, but I'm not certain about the main and EFE samples. Clearly, several people have already built this design and claim that it works, so is there a discrepancy between the schematic and the actual board? There's something a but fishy here that needs to be clarified.

[kt315]

Also dial in a highest frequency for the transmitter, it will give better response.

highest freq gives NOTHING, this is pulse induction not VLF, you get only the overrun of the capacity of the batteries.

[eclipse]

Also dial in a highest frequency for the transmitter, it will give better response.

[eclipse]

Hey guys i have my pc back to full health yay! so i can continue with the barracuda build, in the mean time i have made a coil with 0.5mm enamelled wire 14 turns wrapped with 1mm plastic spiral wrap and a mesh sheild taped on with paper tape, OK! so i have tried the coil and the movement issue is 90% gone but the coil is so slow i may as well just dig random holes at the beach with my son i will have better luck! but it is a step in the rite direction .

what wire would you sugest i buy? i have found this?

http://www.ebay.co.uk/itm/400814050318?_trksid=p2060353.m1438.l2649&var=670366097424&ssPageName=STRK%3AMEBIDX%3AIT

any good? or junk?

try new coil with 22-24awg teflon stranded wire. Insulate the windings with teflon tape (used by plumbers) as much space as you can afford between the coil and shield. Use low capacity coaxial cable, no more than 100ish pf per meter and make it as short as possible ie 1.2m is optimal. I havent built this device but response is faster when adding a diode in series with the mosfet drain.

[Old cart]

OK. I have pin 1 at +0.49. So just hanging in there :-)

Readings are:
Pin 1: +0.49
Pin 3: +0.48
Pin 5: -0.12

I'll try the "nip and tuck" operation (post #325) in the morning, when I'm more awake :-).
Looks simple enough and sounds a very good idea. I should mention that my 79L05 only puts out 4.93V. I don't think it is relevant to the readings, or is it?. (It was originally 4.95V and as it was under 5V I assumed it was faulty. I see a post in another thread that says the similar 78L05 can be below 5V, so assume this is not a real problem.)

Ray

Those voltages indicate that the clamp diodes in your device are doing their job. Maybe that is why this chip is working great. Pin 5 is smaller because there is larger resistor in that path. That is normal behavior.

[Qiaozhi]

Looks simple enough and sounds a very good idea. I should mention that my 79L05 only puts out 4.93V. I don't think it is relevant to the readings, or is it?. (It was originally 4.95V and as it was under 5V I assumed it was faulty. I see a post in another thread that says the similar 78L05 can be below 5V, so assume this is not a real problem.)

Ray

It's not a problem. The 78L05 has an output voltage tolerance of +/- 5%.

[raygdunn]

Ray, that is a good looking trace, save the TV noise! It does appear as though one of our members has identified the reason why the 40106's get degraded. It is not taking the input put voltage to 0, it is taking the input voltage higher than .5. This can happen on pins 1,3,5. If it gets over .5 it can break some chips. In impulse's case it is over .5V.

A working circuit is a thing of beauty so you may not want to try it but post 325 has a potential solution to the chip breaking problem.
Just to satisfy my curiousity could you measure the DC voltages at pin 1,3, and 5 relative to ground ( pin14)

If if you are not comfortanble doing this that is fine.

OK. I have pin 1 at +0.49. So just hanging in there :-)

Readings are:
Pin 1: +0.49
Pin 3: +0.48
Pin 5: -0.12

I'll try the "nip and tuck" operation (post #325) in the morning, when I'm more awake :-).
Looks simple enough and sounds a very good idea. I should mention that my 79L05 only puts out 4.93V. I don't think it is relevant to the readings, or is it?. (It was originally 4.95V and as it was under 5V I assumed it was faulty. I see a post in another thread that says the similar 78L05 can be below 5V, so assume this is not a real problem.)

Ray

[Old cart]

The unadjusted trace, To fit now 2V per grid unit rather than 1V.
[ATTACH]35552[/ATTACH] (Noisy as wife watching TV :-) )
Sample pulse seems to have the expected voltage, which I'd guess was the reason for asking.

Ray

Ray, that is a good looking trace, save the TV noise! It does appear as though one of our members has identified the reason why the 40106's get degraded. It is not taking the input put voltage to 0, it is taking the input voltage higher than .5. This can happen on pins 1,3,5. If it gets over .5 it can break some chips. In impulse's case it is over .5V.

A working circuit is a thing of beauty so you may not want to try it but post 325 has a potential solution to the chip breaking problem.
Just to satisfy my curiousity could you measure the DC voltages at pin 1,3, and 5 relative to ground ( pin14)

If if you are not comfortanble doing this that is fine.

[raygdunn]

If it's been built wrong, then all bets are off. Was just pointing out that this is not a nice way to treat logic ICs. It's an old schematic and it was most likely a noticeable saving in parts and assembly to omit voltage underswing protection. Low current outputs are a blessing in this sense.

Where was the scope common connected in the above picture, raydgunn?

The unadjusted trace, To fit now 2V per grid unit rather than 1V.
(Noisy as wife watching TV :-) )
Sample pulse seems to have the expected voltage, which I'd guess was the reason for asking.

Ray

[Old cart]

your schematic is BBBAAADDD.... DELETE IT AND FORGET. (i had deleted all those schematics drawn by Alex - much mistakes).
[ATTACH]35162[/ATTACH]

Ok i have taken readings from the 40106 and pin 1,0.55v 2,4.9v 3,0.48v 4,-4.8v 5,0.16v 6,-4.7v 7, -4.9v and pin 14, 0v. i have borrowed an o-scope but it will not turn on atm batt is flat across the coil and 8.3v AC 0.22v DC and now the board does not function at all nothing not a beep unless i pull the power off it and i get a whine as the power drains, nothing changed ?

Here is a good example. Impulse has .55 volts on pin 1 of the 40106. This is an actual measured voltage, not a simulation. This clearly exceeds the absolute maximum input voltage rating of TI. This 40106 also is not working correctly. It introduces additional pulses that should not be there. They are runt pulses ( smaller than normal) the occur on the rising and falling edges of the transmit pulse. These may have no effect on the Baracuda operation, but they should not be there!

One simple solution would be to cut the trace that leads to the +5 volt regulator very near the 33k resistor attached to pin 1 of the 40106. Cut the trace between the 33k and the regulator NOT between the 33k and pin 1. This will allow R17,18, and 19 to float. Then tie this point to pin 14 of the 40106 with a thin jumper wire. This hold place pins 1 ,3 and 5 at 0 volts which is still a logic high and will not exceed the chip specs. However it will likely alter the timing of the two timing pulse and require resistor value adjustments.

if someone can look this over it advise if I have this right that would be great.

[Old cart]

your schematic is BBBAAADDD.... DELETE IT AND FORGET. (i had deleted all those schematics drawn by Alex - much mistakes).
[ATTACH]35162[/ATTACH]

Actually on this schematic the resistors connect to Vdd, which is 0 volts on the Barracuda. So the board looks wrong!

[Old cart]

It shows a 5V supply for the 40106 but some of the timing resistors tie to 5V above
the positive pin!
--
yup. and what??? you want to say that is wrong?

Yes that is wrong. See the absolute maximum ratings for the 40106 input voltage.

http://www.ti.com/lit/ds/symlink/cd40106b-mil.pdf

This is the TI B version of the chip.

The inputs can never go above .5volts in the Baracuda or this spec is violated. Since the input impedance is high the resistor in series drops essential no voltage. Depending on the protection diode this voltage could be .7 volts or higher. In this thread alone we have seen at least two damaged 40106 problems. This could well be the reason, or it could be simple static damage.