Baracuda Build Blog

[Koala]

Been look at this again.

Tried a new tip127

Tried a new coil

Tried different and longer cable to get the coil further from the board

All no difference

Tried a 2n222 still not working but different can detect gold at 2" at 8 volts but still noise on coil flyback


here are a few traces

[Koala]

Getting somewhere. If I add a 220µF capacitor from between the 78L05 and GND the the flyback does not have the noise on it. Have to do some work on delay and offset as these are now different but gold is now detected approaching the coil not moving away

As most people don't have this problem does it mean my 78L05 is faulty ?

[6666]

Could be faulty, they can do some strange things sometimes, can you change it ?

[porkluvr]

Getting somewhere. If I add a 220µF capacitor from between the 78L05 and GND the the flyback does not have the noise on it. Have to do some work on delay and offset as these are now different but gold is now detected approaching the coil not moving away

As most people don't have this problem does it mean my 78L05 is faulty ?

Maybe you should have read post #21.

Thank you for the entertainment. You're like a puppy who's almost drowning in the deep end of a swimming pool but eventually dog-paddles to the edge and finds a ladder to climb out.

Now, climb out of the pool and shake yourself off, you poor little puppy. Or, stay in the pool and drown. I won't care either way.

[Koala]

Still drowning throw a life line

Something still not right. @ 7.5 supply volts the +-5 are spot on unit works okayish . @ 8.2 supply volts +-5 volts are still spot on but unit does not work but threshold sound is more stable.

[silverdog]

Use a 12v supply, 8 x AA or 12v regulated wall charger
i had problems when trying to use 9v, or rechargeables

[Koala]

Use a 12v supply, 8 x AA or 12v regulated wall charger
i had problems when trying to use 9v, or rechargeables

Put a heatsink on the TIP127 and tried 12V all was going well adjusted delay and offset and was getting about 4" on a gold ring then bang. Thought something had gone on the board big time but it was one of the batteries that had exploded.

Something on the board has also gone though as now there is no threshold sound and 12V but still okay on 7V however the flyback is now wrong. There is a distinct step halfway through the flyback and on 12V the TIP127 instantly gets hot.

[Koala]

This is what the flyback looks like now

[Koala]

back to a working ish detector. Changed the 2n2222 and TIP127 only to find it was the scope probe causing the glitch in the fly back. Threshold is back but don't know which one was the problem as I was only looking at the fly back.

Threshold was very unstable pulsing in an out changed the 78L05 and it's much better. Detection of iron is great but can only just detect gold no matter where the delay pot is set. Delay pot seems to have little effect.

[Koala]

Whoops on replacing the 2n2222 I put it in backwards turned it round all is good. Not done any setting up and well over 8" on a medium gold ring.

Time for some testing and adjusting.

[Koala]

Whoops on replacing the 2n2222 I put it in backwards turned it round all is good. Not done any setting up and well over 8" on a medium gold ring.

Time for some testing and adjusting.

Tried a few different coil does not seem to make much difference. Tried iron copper steel bronze and gold. Get about 10" on all UK 2p size target tried coils from 7" to 11" and there is only about an inch difference in depth ?

Only getting about 150 volts at the coil with a TIP127 does this sound about right ?

The 7" coil sounds very good to me 9"-9.5" but don't seen much improvement going to 11" got a POT for the damping at the moment but can't dial in any more performance.

Removed the smoothing capacitor from the 5 volt rail and there was a noticeable increase in depth so I was triying to fix something that was not broken



The Baracuda does seem to be rock steady and very consistent just need to increase it depth with a larger coil. Think some of you are getting about 15" with the 11'' coil am I right with this.

[mohandes]

Tried a few different coil does not seem to make much difference. Tried iron copper steel bronze and gold. Get about 10" on all UK 2p size target tried coils from 7" to 11" and there is only about an inch difference in depth ?

Only getting about 150 volts at the coil with a TIP127 does this sound about right ?

The 7" coil sounds very good to me 9"-9.5" but don't seen much improvement going to 11" got a POT for the damping at the moment but can't dial in any more performance.

Removed the smoothing capacitor from the 5 volt rail and there was a noticeable increase in depth so I was triying to fix something that was not broken



The Baracuda does seem to be rock steady and very consistent just need to increase it depth with a larger coil. Think some of you are getting about 15" with the 11'' coil am I right with this.

hi
my friend i make baracuda before but have low depth .
so dont wast your time . i thing real problem in transistors ( but i dont read last posted )

[Koala]

Been play some more with the coil increased the number of windings on the 11" diameter coil .5mm wire to 30 turns. Readjusted the delay and now at 13" for a gold ring. Pretty sure I don't want to be digging that deep on the beach most of the time

Will try and refine it some more but happy with the result.


tried both rechargeable and zinc carbon batteries and the depth is the same. Only difference is the threshold is smoother with the carbons will get a fresh set today and see if that makes a deference

Then onto matching the FETs

[gerson]

"Removed the smoothing capacitor from the 5 volt rail and there was a noticeable increase in depth so I was trying to fix something that wasn't broken"
hello friend. could you be more specific, regarding which rail or point or enumerate the capacitor you removed. thanks. seu post 41....

[Qiaozhi]

"Removed the smoothing capacitor from the 5 volt rail and there was a noticeable increase in depth so I was trying to fix something that wasn't broken"
hello friend. could you be more specific, regarding which rail or point or enumerate the capacitor you removed. thanks. seu post 41....

Do you know that you're replying to a post that is 9 years old?