Barracuda Legend Kit Problems

[6666]

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

[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?

[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]

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.

[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]

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?

[kt315]

[kt315]

Its very easy to test any NPN or PNP transistor. When you have the correct pins the led will light.

CHILDREN GARDEN!!! i give you right way! you can CAN NOW! check all semiconductors and MOSFETS too!

[Tim]

Maybe. I should have these joiners to pots soldered, but for now I need the serviceability to be able to remove the lid.
I now can detect an Oz 10c piece at 4inches.
My coil is 10x5 elliptical, .5mm enamelled. 445uH and 2.1 ohms at board. Changing between RCA cable and lowR speaker wire cable(both 1.5m) makes no difference to sens or measurements. Moving my electric drill closer to coil increases sensitivity, to a point, then moving it closer sense decreases dramatically.
For best sens on coin I have delay trimmer at halfway and max. sens is with 10K about 1/3.
Going back now to try a few more 40106s,5534s, and return the TL062 to the 412 spot-one at a time. Also will try 220R and 470R dampers. More offset twiddling too.
I need at least a doubling of sensitivity to justify this detector.
Still no threshold tone.....

[ripsdevala]

Maybe your cable joint to 10k pot is loose, or not join properly

[Tim]

Woo-Hoo! PN2222 reversed. Offset pot removed and checked. 0v available at offset-best signal at approx.100mV. I just can't understand how it was working with the 2222 reversed before??. Now for delay/coil/damping/ic swap experiments, as still only and inch with the Oz 10c piece.
I have read all of the build thread, and all the probs thread previously, but I'll keep browsing. Jeez, I hope I can get this thing working usefully.
Thanks for the input boys&girls, especially 6666. I was about to bin this one and move on- my next project is the Newhobby Magnum clone.
That tranny tester's a keeper 6666-showed me the PN2222 did indeed need to be reversed. Despite checking the datasheet, I still stuffed up.
The Magnum also has an auxillary circuit, for coil setting, which I will add to my arsenal.
Now, back to getting a bloody threshold signal...any ideas why I have none? Anyone?

[6666]

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.

[6666]

Great advice thanks Andy and ripsdevala. I will replace reverse the PN2222 and replace the offset trimmer and persevere.
Geotech has been a wonderful educational resource for me. I will buy ITMD asap, and learn to use my scope.
It may be a day or 2, but I will report here for the benefit of others. Thanks.

Its very easy to test any NPN or PNP transistor. When you have the correct pins the led will light.

[Tim]

Great advice thanks Andy and ripsdevala. I will replace reverse the PN2222 and replace the offset trimmer and persevere.
Geotech has been a wonderful educational resource for me. I will buy ITMD asap, and learn to use my scope.
It may be a day or 2, but I will report here for the benefit of others. Thanks.

[silverdog]

when you say PN2222 orientated with silkscreen - that should be turned 180 degrees relevant to silkscreen
A P2N2222 can be inserted as the silkscreen