Barracuda Legend Kit Problems

[kt315]

[Tim]

This is way above my head KT. I gather it is a universal component testing circuit for use on an oscilloscope???

Anyway, now I have tried a few more component changes. I am at 750R with the damper, Tried 82,220,330,430,510, and now have Oz 10c piece at 5 inches, and can detect a ladies fine gold ring at 2 inches, and an Oz 5c at 4 inches. Previously these were un-detectable.
TL062/LF412 no difference, so back to 412.
My batch of 5534s, I have now binned 5 out of 10. 2 with broken pins, 3 failures prior to or during 2222 dilemma. The HEF 40106s came pressed into styrofoam, causing static, and both have now failed. The CD40106 is OK, but I have not tried the other 9 of them. I will try not-so-cheap suppliers next time, and different manufacturers.
Still no threshold tone........
I did have one intermittently, with top cover skewed, before the sparks, and 2222 inversion.
Any suggestions please?

[Koala]

To Silverdog

Andy its time to change the 2222 to another npn transistor that matches the silkscreen and is manufactured with only one type number and leg configuration.
This confusion just causes to much heartache for some constructors.

caught me out.

Ordered the right part but was supplied with PN2222. Didn't check and just fitted. Funnily enough the detector work quite well on low voltage but at 12V the TIP gets instantly hot.


No doubt the TIP would not last many minutes at full voltage.

Dangers of eBay always double check.

[Tim]

Another angle at the no threshold problem. Which resistor value would I lower/change, or resistor/capacitor combo change to increase the threshold? I have sort-of figured R24/C13 on the KT315 schematic. But perhaps the problem is still with my 40106, or VT3/VT4 combo?? Or maybe VD1 or 2 faulty?
If the R24/C13 change is an option, what values please?
I am at a loss to the poor performance/lack of threshold.

[FatBob]

I have 2 Surf PI's that have low sens. I haven't fixed them yet but have a few ideas.

1 is external noise, we have a radio station nearby that causes problems on other devices here.

2 is lack of current. My laptop batteries are acting weird and my power supply is only 250 ma.

3 is using wrong object to test with. I am used to VLF's where you can wave most anything.
Am gathering up some good targets to test with.

4 is tuning. Some have "fixed" low sens by adjusting the TX width and RX pulses.

5 I have had one PI blow up the 1K resistor on the input and not work after that. I bought some
high voltage ones to use in that place. That's not mentioned much but is an issue.

I'm watching to see what works for you!

[Tim]

Thanks for the reply FatBob. I have a Tacoma56 SurfPro DD, and with the ML CommanderDD 10x5 it's and awesome machine, and will match my Infinium with the 8 inch mono on my 1.7g flour gold test-about 7 inches in-air.
I'm reasonably sure 'tain't external noise, although the times I did have a threshold, it could have been the reason.
Maybe voltage (10v), or current. I'm using 3x18650's@2500mA(11.1-12.6v), and need the 10v reg, otherwise my 7660scpaz's cut out with fully charged batteries-don't have a 12v reg currently, but changing to a LT1054 converter, when they arrive. I will turf the reg then. I tried a LM317T regulated to 11.5v, and the 7660 still didn't work.
I'm leaning towards a faulty/poor 40106 still, so more/better/differents on the way.
In the meantime I will temporarily lower Rs on either side of thresh pot for a try.
If none of this works, I'll change out the 4148s, then the matched fets one at a time to see if un-matching them gives me a threshold.

I am sure some of the gurus are reading this, and shaking their heads- some input please?

[6666]

What do you search for with the Commander DD 10x5 ?

[Tim]

Anything and everything 6666. I'm about 300km from "The Triangle", so it's a case of having a machine for each purpose-I have 21 now counting the 'Cuda.
The emerald and diamond ring was found 3 days ago with the Surf. The slug,shell and 20c coin today with the Compass 94B.
This one would be a great project-simple and sensitive-but the coil may be tricky.
I finally secured a concentric coil for my GMT last week-apparently they are even more sensitive to sub-gram gold than the DD.
Mongolata goldfield is my closest, but my area here is a WW1 soldier-settlers district, and Paddle-steamer railhead, so I find things of interest nearly every swing.
An upcoming project is the Falcon MD20, to compliment the blacksand meter on the GMT.

Sorry.Off topic. Any ideas about my Bara threshold. Anyone?

[Old cart]

Anything and everything 6666. I'm about 300km from "The Triangle", so it's a case of having a machine for each purpose-I have 21 now counting the 'Cuda.
The emerald and diamond ring was found 3 days ago with the Surf. The slug,shell and 20c coin today with the Compass 94B.
This one would be a great project-simple and sensitive-but the coil may be tricky.
I finally secured a concentric coil for my GMT last week-apparently they are even more sensitive to sub-gram gold than the DD.
Mongolata goldfield is my closest, but my area here is a WW1 soldier-settlers district, and Paddle-steamer railhead, so I find things of interest nearly every swing.
An upcoming project is the Falcon MD20, to compliment the blacksand meter on the GMT.

Sorry.Off topic. Any ideas about my Bara threshold. Anyone?

Check for shorts between the wires going to the threshold pot, also on the pcb itself. Check to make sure the threshold pot is OK. Last check the resistors attached to it for correct value and operation.
The 40106's have been major cause for problems as have the 40106 pull up resistors.
But until you have the supplies all correct all bets are off.

[ripsdevala]

Old chart I need a help, view days ago i fried diode 4001 closest to + and - battery,because i try to put three 3.7v li-ion battery 18650, Its dead and short, I already change the fried one with 4007 and work again, the problem is when i use 8 alkaline battery with 12+volt, the 7660 IC become hot, cant hold it more than 2 sec, its burn my finger, did I miss something, or other 4001 is short also.

Thanks

[Tim]

Thanks Old cart. My board is spotless and traces correct.Will check/change the thresh pot and have a squizz at the Rs there. I did notice the pullup Rs changed on the Alex version from earlier ones, so worth consideration. Although my 7660s are scpaz, I fear this batch are inferior, as my 40106s, so I will replace both when my new batch's arrive.
I won't cut and shut anything until I get a voltage converter that can handle 12.6v.

Thank you sir-sound advice, and a process of elimination for me to follow.

All my builds so far I use 3x18650s, with an on-board 4A charge controller(alongside batteries in pic above). The method in my madness is that they can be charged from any un-regulated 12v source. I have a 12v 1.5w solar panel mounted on my stem for constant charging, to extend battery life on long hunts, and charge while idle.

ripsdevala, I would hazard to say your 7660 needs replacing.

[6666]

Just for the record mine is a TC660SCPA absolute max input 5.5v, and no sign of any warmth.
and HEF40106BP made by NXP, I think I got that from Jaycar.

[Old cart]

Old chart I need a help, view days ago i fried diode 4001 closest to + and - battery,because i try to put three 3.7v li-ion battery 18650, Its dead and short, I already change the fried one with 4007 and work again, the problem is when i use 8 alkaline battery with 12+volt, the 7660 IC become hot, cant hold it more than 2 sec, its burn my finger, did I miss something, or other 4001 is short also.

Thanks

the only way I can see the 4001 fry is that it was installed backward. 7660's can get hot with 12 volts applied. It is only rated for 10.5 volts absolute maximum. You could try the S version or use only 7 cells.

[eclipse]

Use LT1054 instead

[Old cart]

Thanks Old cart. My board is spotless and traces correct.Will check/change the thresh pot and have a squizz at the Rs there. I did notice the pullup Rs changed on the Alex version from earlier ones, so worth consideration. Although my 7660s are scpaz, I fear this batch are inferior, as my 40106s, so I will replace both when my new batch's arrive.
I won't cut and shut anything until I get a voltage converter that can handle 12.6v.

Thank you sir-sound advice, and a process of elimination for me to follow.

All my builds so far I use 3x18650s, with an on-board 4A charge controller(alongside batteries in pic above). Resistor The method in my madness is that they can be charged from any un-regulated 12v source. I have a 12v 1.5w solar panel mounted on my stem for constant charging, to extend battery life on long hunts, and charge while idle.

ripsdevala, I would hazard to say your 7660 needs replacing.

Look at the posts found in this thread
http://www.geotech1.com/forums/showt...it-Rev2)/page3
the pull-ups values have been changed as have the voltage they are referenced to. Plenty of good discussion there. You wil also find a new schematic further down that captures all the changes. But read it all. Even the last schematic has a 2.2M resistor in the threshold circuit. Later in the thread the value is corrected to 39 K as I recall.