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Hi,Originally posted by Molzar View PostDid some measurements on original TGS with original coil (8 inch)
TX Voltage = 8.2 pk-pk! Was very shocked
this was so low! Checked supply voltages (11.8V batt, 7.9V off regulator) so those are OK. Could be due to coil (Tx ~23 ohms) but seems very low. Any ideas why?
Also looked at Tx Rx signals on scope. Are many different from handmade with DD. Rx shift to left with copper coin. Will have to do better experiments, to much rush now.
Also one more component difference (on schematic) 10pf cap on pins 6 & 7 of LF353 is 5pf. Don't think big change but that is it. I update schematic.
Molzar
the 5pF cap was already checked: no big difference using also 10pf there.
The fact you read just 8.2Vpp at TX is interesting... but performance is good also at these low levels... say around 10Vpp. Sure, you'll get better on higher voltages like the famous 16Vpp (actually a bit less but very near to 16Vpp, that depends on output of regulator... if >8V you get more).
The 16Vpp range is enough to run device stable and get good detection depth: good compromise.
The 8.2Vpp you found is maybe related to some enhanced stability issue, like reducing false signals due to minerals etc but that reduces also detection depth a bit.
Maybe the tis75 there is selected to keep under 10Vpp the tx voltage.
Kind regards,
MaxComment
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I agree with Nakky. Kurtie posted accurate pcb.
Also nice video to see. If you pay attention on some testings in video, you can notice that original TGS is not "deep" in air as our homemades.
Also voice said something like ".. i havent used Notch funciton...dont want risk to miss some good targets..."
Comparing this what i saw in video to results i got with my homemades...i can only be even more satisfied..
Max welcome back! Nice to have you here.
Regards!
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Very nice, get to see the beast in actionOriginally posted by aft_72005 View Post
. What is that coil, LASER?
I believe the results, similar to my Compadre -- however, why the little beep and movement of the detector during the pause where he changes to good targets? A suspicious person might think he changed some knob setting
.
Thanks for posting.
-SBComment
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Just curious - is Kurtie pcb a scan or made by hand? It is different from Molzar PCB? If scan, is it newer model?Originally posted by ivconic View Post
Regards,
-SB
yes good max back!Comment
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Hi simonbakerOriginally posted by simonbaker View PostVery nice, get to see the beast in action. What is that coil, LASER?
I believe the results, similar to my Compadre -- however, why the little beep and movement of the detector during the pause where he changes to good targets? A suspicious person might think he changed some knob setting.
Thanks for posting.
-SB
Yes it is interest , also seeing ivconic movie.
Yes ,coil was laser . also my handmade tgs mask iron goodly .
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If you pay attention on some testings in video, you can notice that original TGS is not "deep" in air as our homemades.
I agree completely with you. My handmade tgs deeper than
Original in same condition .
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Hi Max
Also I am glad see you again here.
I hope, you be able solved your problem.
Best regards.Comment
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[quote=simonbaker;82114]Just curious - is Kurtie pcb a scan or made by hand? It is different from Molzar PCB? If scan, is it newer model?
Is made by hand.The only diff is,to make a very good coil.Grt Nakky.Comment
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damn troubles
Hi all,
thanks for your kindness. My troubles aren't totally solved at now, but I have some more freedom to write here more than in last weeks I've made... rarely.
Hope to solve at best, sooner or later. Will be not easy but some things require time also. Cause are really personal issues I will not discuss (too off-topic also) about, but thanks for your kind messages, I appreciate.
Just I have to recover some time and nervs to step back at last developments I had to stop several weeks ago.
For now, I have to say that more good work is being made here on geotech by all folks, I appreciate new pictures from Molzar too.
Really, I have to say that more and more I agree with you folks, expecially Ivconic: the homemades are sure better cause of very accurate tuning than factory made, expecially at coils things.
The factory coils are not so good but just average: I've tested some and all failed to beat similar (by type/dimensions) homemade coils made by me.
So... something at original coils is far from perfection, that's both for Laser and Tesoro, but I guess some Troy stuff is much better. It's the tuning procedure... factory have no time to tune at optimum each coil.
Kind regards,
MaxComment
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[quote=nakky;82137]Exactly what I think. No great MD exist without a great coil.Originally posted by simonbaker View PostComment
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Hi max welcome back,I agree with you about coils.Grt Nakky.Comment
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[quote=Max;82152]I would like to do experiment (and will if have money for wire and time). Maybe some already done it.Originally posted by nakky View Post
Make many copies of exact same size coil but with thicker and thicker wire (don't care how heavy for experiment). How does wire gauge affect depth. Theory would suggest that the lower resistance of coil, higher Q, more current, greater magnetic field -- same as increasing voltage but doesn't use more power. Does it go deeper in air? In soil?
Also, instead of using thicker wire, start with thin wire. Then use double strand. Then triple, quadruple, etc. (like homemade Litz wire). How does it affect depth. Compare to increasing voltage with single wire.
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Tesoro coils mostly concentric for TGS, etc. Double-D most popular here on Geotech. Is improvement mainly because of Double-D?
Tesoro maybe makes decision to keep most customers happy -- good pinpointing and good detection of smaller objects with concentric, easier to use for first-time MD users. Double-D good for larger objects, harder to pinpoint. Can anyone here make a concentric same size as Tesoro and still get deeper?
Regards,
-SBComment
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Max: "...I guess some Troy stuff is much better..."
Huh, you got that right! I was amazed with X3 and it's coil! State of the art!
They really pay a lot of attention making those, hard to beat for sure!
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Coils
Hello Simon …and all other friends.
Coils can keep you busy…. some notes (not really new..)
The transmission power you put in the transmit coil, to weak is a problem , you have no detection depth…. to much makes nulling the coil a problem and it eats battery’s ( some boosts are made in the transmitter can give some more transmit power,.. some more depth but you also get more chatter)
The working frequency to high gives more ground effect , is more sensetivetie to tin gold an small stuff, more problems in discrimination ?A low frequency needs more power and is less sensetiv to small gold bud also less problems to ground effect.
The coil type the DD type is better in ‘hard to detect’ ground open centre is better in discrimination.
The match for the transmitter/ receiver. I still think that the transmit freq. has to match the receiver freq. for the best sensitivity. This means that after you got a working transmitter circuit you have to match the receiver for the same freq. cq adjust is with caps for the best sensitivity.
The shielding from the coils in the past I used for DD types graphite spray and alu foil I think that alu foil is better ( less chatter) but that spray gives a little more sens.
After reading the BBSailor PI coil making instruction (very good !) I have used the scotch 24 for screening the DD coils. It is not really tape but a sort screening mesh that you also see on coax cable. I cut the sleeve open and stick it on double side tape, then it is very easy to turn it on the D coil. ( needs ca 1 meter for a coil 20cm, you cut the ca 6 cm wide mesh/tape in three parts from 2 cm ). ( I can make some photos to explain…)
This scotch tape, together with the double side sticking tape is the best I have used till now.
For open centre coils I have the suspicion that the distance between the coils is imported
(Just like sound speakers you can have a place in a room were the faze from the sound nulls the result )
I made open centre coils always starting with the large transmitter coil, that is : diameter and number wire turns must give the expected frequency ca 14 kHz .Greater than 23cm coils I used .30mm wire (for ca 14 kHz ca 100 turns), smaller than 23 cm I used 0.25mm wire. For the first receive coil( also 23 cm) add 16-18 turns same wire same turning direction. For the small inner coil( ca 14 cm) you have to wind ca. 160 turns in opposite directions to null the voltage that the 16-18 turns from 23 cm see. Than you look at the receive result after the first opamp, adjust this signal with caps for a good distortion free sinus.
(for best results on the detector that you use for that coil)
The open centre coil ( somewhere are some photo’s on the Geotech coil part ) I have made this way, it was …not less sensitive than bought coils
It is hard to give exact numbers as the strengt from winding the coils an a little difference in cm’s have direct effect. As screening I use graphite spray for open centre coils.
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For DD coils read all Ivica’s mails !
I know not all is new and gives not much answers ……. if somebody knows better way’s let us know….
Best regards.
Ap
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