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Hi,
I'm drinking the coffee... and I remembered all the story about confusion and references
In the Gifford's (well is my reading of it) system the reference is on the Y axe and positive are clockwise measured:
at -90 (-X axe) he has ferrite response... and clockwise turning a +5° he has the "limit" for soil if we talk about Payne's stuff so: -90+5 = -85°
Actually he has mixed up stuff too on figure nr. 2 of patent giving an "alternative" way (compare fig.1 and fig.2 ... in fig.2 the +R axe that lay at +90 is actually the origin for fig.1 , with phase equals zero)!
Payne's coordinate system uses also an axe as reference for angles BUT counterclockwise for positive angles ...so Payne's -5° describe a movement like +5° for Gifford (here the confusion):
when he said that ferrite is zero he means that he's in the origin, on the reference axe, with the ferrite response... and when he said that a soil could give till -5° he means that conductive (R component) make RX signal shift phase clockwise respect to ferrite response (pure mineral)... like happens when a conductive metal effect is detected.
The confusion is in that Payne's method uses negative angles for effects due to increasing conductance ... where Gifford's uses the positive for that.
That's why I think Gifford's method is better... cause when can talk of negative phase for e.g. iron... and positive for silver... and not the opposite.
Of course, just conventions... but all this stuff is really confusing changing the reference all the times.
Kind regards,
Max
I agree - this is all very confusing. However, I think Fig. 2 is correct in Gifford's patent. The axis values are referring to the phase of the oscillator, whereas the target phases refer to the received signal. For example, at the top of Fig. 2 it says 0 degrees "X" axis, and "mineral in soil". The 0 degrees is shown in the top waveform of Fig. 1 for the oscillator and is marked as "Mineral Sample Phase "X". "Mineral in soil" in Fig. 2 refers to the phase of the second waveform of Fig. 1 measured at the 0 degree point of the oscillator. All the other target information follows on from this.
Hi Geo,
you can try reducing time of exposition... and making the solution more weak... to give you more time when removing eccess resist from it... but it could work or not depending of status of photoresist... sometimes the alteration is on 100% of it so you simply cannot reach your result with it.
Heat is the big problem for conservation of that boards... then time is the second critical factor (1-3 years good, 3-7years still good, more than 7years... is a challenge!)
The big problem with lowering the time is that some resist could remain there ! and is very tricky finding the right "seconds" of UV (yes seconds) you need to remove it good from board.
One time I repeated 22times the procedure to get a working PCB from old stuff...more than 10years old. After that I've made it good... but then considering the time and efforts required... it isn't any good and so I recovered boards and painted with new photoresist can all them. And now I make smaller PCBs at first attempt with them!
If you have many boards of good quality... I suggest you clean them one by one and buy a can to repaint again with fresh resist (I've done 35 small 10cmx8cm using a 12eur can), then find a cool place to store using a black paper or similar to cover from light.
Best regards,
Max
Hi Max
Τhank you for your information. I deal with photosensitive pcbs more from 20 years without particular problems. But now I cannot occupy what happens ...... likely the photosensitive material it spoiled. I bought from ebay 2 sprey in order to convert normal pcbs in photosensitive other again it does not work. I expose pcbs in UV for 8 seconds and afterwards i immediately present in caustic soda. it is presented the drawing and automatically is dissolved the photosensitive material and remains only the pcb. Really this time I have all lost. We will see...... My Regards
Oooh!Huh! I had same doubts about Payne's and Giffords explanations! Sssheeeesh! I tought all missunderstandings came due fact that i am Serbian and English is not my primary language, so i couldnt understand some phrases or slang they might be used.....It was pretty strange from the start!? In 2004. i downloaded almost all intersting patents from uspto.gov.net...At the time it was possible to install Alternatiff plugin and see originals, also download them. Now i think they changed something. I cant see and download any more from there? The heck...! Max, today i experimented a bit more with nulling. I made another coil, but this time larger one,eliptical (copy of Garrett Eliptical shape)..So i did like you suggested-put 1K on RX and of course 15nF. All measurements done with multimeter at 200mV AC. Well....i was right; when almost nulled, but without resistor, voltage is 0.012mV. With resistor was 0.009mV...? Fake as i told you! It is much easier to look at 0.012mV and null a bit more coil to achieve less voltage than to look at 0.009mV...if you know what i mean. Less error! So when i gain 0.000mV only with 15nF and later add 1K, voltage remains 0.000mV - no changes of course. But if i try to achieve 0.000 with resistor included...and gain it, and later discinnect it an measure again; i gain some voltage not absoulute zero, for example 0.002mV...So resistor produced error of 0.002mV....I think that's why your coil is giving you some 5.5mV. You probably used oscilloscope to measure and resistor was included there.. I insist you (for your benefit) to try with some opened coil and see yorself. Just put 15nF without resistor. Null it as less as you can. Than add rsistor and you'll read higher voltage for sure...on oscilloscope or multimeter, the same....
Those are 2 coils i made yesterday and today.Drying yet. It will need few more
hours to get dried and stiff.Also there is a mass which used to fill up coil
housings. Sort of 2 component pitch. When dried, it is hard and fast as steel.
Best so far. Cold drying no relative movements. Larger coil is 800gr and smaller
680gr. A bit heavy but almost unbreakable. I can hit it with hammer very
hard - not even a small scar...Superb!
And photo of my (my personal-not for sale) TGSL, which i am using now.
The one who collected those 254 coins in no time. Real killer! Coinkiller!
I didnt payed much of attention on appearance, it is a bit brute but real
machine!
Others i made for sale are looking much better,nice outfit...Havent neither one
right not to take photo. I'll do that next time when finished...
"...Just put 15nF without resistor. Null it as less as you can. Than add rsistor and you'll read higher voltage for sure...on oscilloscope or multimeter, the same...."
"read same voltage for sure.." - error!
Or do oposite; null it with resistor included,than omit resistor and you'll read HIGHER voltage for sure! So less error in readins (and nulling) will be if resistor is omitted! I confuse myself with all those explanations here...!? How the heck you will understand this...!? Regards!
Hi Max
Τhank you for your information. I deal with photosensitive pcbs more from 20 years without particular problems. But now I cannot occupy what happens ...... likely the photosensitive material it spoiled. I bought from ebay 2 sprey in order to convert normal pcbs in photosensitive other again it does not work. I expose pcbs in UV for 8 seconds and afterwards i immediately present in caustic soda. it is presented the drawing and automatically is dissolved the photosensitive material and remains only the pcb. Really this time I have all lost. We will see...... My Regards
Hi Geo,
8 seconds ? What's the power/number of your UV lamps ?
Maybe you mean 8minutes ?
If you expose for 8seconds and stuff goes away in soda solution that means the photoresist is totally busted.
I have a 32Wx4 UV set and it took from 3 to 5 minutes do shoot circuit on photoresist... depending on type of it, how much is old etc.
Normally I use 4minutes timing (the unit has a 0-10minutes programmable timer) and get extremely good results with factory made photoPCBs... and also my own sprayed ones.
Timing for old photoresist I used are from 2 minutes to 8 minutes... but it's rare I use old stuff... I've done in the past and waste lot of time with that.
I use fully transparent sheets with laser or ink-jet drawings (black)... ink-jet when pads and tracks are large...laser for thin stuff (e.g. like computer cards).
Soda-solution need to be 10gr in 1Liter or less (7-8gr/Lt are good for 30seconds developing)... 10gr require often 15-20 seconds to make melt/dissolve all the residual stuff.
I use also 1gr/Lt for desperate cases... when I need more time...and "care".
When you buy the spray there must be a label on can or a separate instruction sheet with developing procedure and hints... there must be also suggested exposition time.
Best regards,
Max
PS: I hope you solve that problem quikly so you'll have your TGS/TGSL up and running... it's worth !
Oooh!Huh! I had same doubts about Payne's and Giffords explanations! Sssheeeesh! I tought all missunderstandings came due fact that i am Serbian and English is not my primary language, so i couldnt understand some phrases or slang they might be used.....It was pretty strange from the start!? In 2004. i downloaded almost all intersting patents from uspto.gov.net...At the time it was possible to install Alternatiff plugin and see originals, also download them. Now i think they changed something. I cant see and download any more from there? The heck...! Max, today i experimented a bit more with nulling. I made another coil, but this time larger one,eliptical (copy of Garrett Eliptical shape)..So i did like you suggested-put 1K on RX and of course 15nF. All measurements done with multimeter at 200mV AC. Well....i was right; when almost nulled, but without resistor, voltage is 0.012mV. With resistor was 0.009mV...? Fake as i told you! It is much easier to look at 0.012mV and null a bit more coil to achieve less voltage than to look at 0.009mV...if you know what i mean. Less error! So when i gain 0.000mV only with 15nF and later add 1K, voltage remains 0.000mV - no changes of course. But if i try to achieve 0.000 with resistor included...and gain it, and later discinnect it an measure again; i gain some voltage not absoulute zero, for example 0.002mV...So resistor produced error of 0.002mV....I think that's why your coil is giving you some 5.5mV. You probably used oscilloscope to measure and resistor was included there.. I insist you (for your benefit) to try with some opened coil and see yorself. Just put 15nF without resistor. Null it as less as you can. Than add rsistor and you'll read higher voltage for sure...on oscilloscope or multimeter, the same....
Hi Ivconic,
thanks for the hint, I'll do that way next time... I'll use also one multimeter + the scope to compare readings from both.
Those are 2 coils i made yesterday and today.Drying yet. It will need few more hours to get dried and stiff.Also there is a mass which used to fill up coil housings. Sort of 2 component pitch. When dried, it is hard and fast as steel. Best so far. Cold drying no relative movements. Larger coil is 800gr and smaller 680gr. A bit heavy but almost unbreakable. I can hit it with hammer very hard - not even a small scar...Superb! And photo of my (my personal-not for sale) TGSL, which i am using now. The one who collected those 254 coins in no time. Real killer! Coinkiller! I didnt payed much of attention on appearance, it is a bit brute but real machine! Others i made for sale are looking much better,nice outfit...Havent neither one right not to take photo. I'll do that next time when finished...
Hi Ivconic,
the mass you talk about is something like used in repair for cars... I mean something 2 components (filler+primer) car filler/putty ?
I've tested it to add weight to a coil 2 or 3 years ago... and it's really hard stuff... you can e.g. sand (seems metal after dry ! it's a rock).
I think most of these are poliurethane compounds... that are heavy about as epoxy and also hard... but they, big masses, shrink a bit.
I know there are epoxy based fillers (2 components) that are "loaded" with other kind of plastic (sometimes fibers) and other stuff.
My thought about them is about added stuff... I mean there are some for e.g. home improvement/repair that have aluminium grains inside... other (like car products or insulanting materials for e.g. water) loaded with metal oxides... : if so could be a real problem having that just over the coil !
Many car type have just plastic fibers inside... so are good for the purpose... one have to test making hardening some in an e.g. 5cm diameter bottle cap ... then trying to detect it with MD before using.
I've made some try and detected 1 kind of home-improvement epoxy adesive (maybe... cause is silvery looking... there is aluminium inside).
BTW what's total weight of your detector with DD255x137 ?... I notice gel-type that battery will be under the arm.
No Max, this never used on cars or simillar. I dont know proper name for it.Sort of pitch,resin..? Oh, yes i know; look at some old TV set,flyback transformer and cascade are filled with it, same material. Doesnt shrink a bit. Remains same volume when dry.That's why am i delited with this. No metal particles inside, pure non-conductive material. Other; yes perform nulling on both ways and please inform us here about diffeences... Regards!
"...BTW what's total weight of your detector with DD255x137 ?... I notice gel-type that battery will be under the arm...."
Yes, good question! This one ("katana") is arround 3kg's...heavy but very well balanced. It is kind of hard to work with it more than 40-50 minutes. I usually take short rest,5-10 minutes...It could be lighter a bit. I was thinking to mix this mass with something lighter and try to achive coil weight under 500gr. I'll experiment with this further.
Hi Max. Now it is not my good time. I don't know why but i can't make good pcbs. I have 4 UV but i dont remember the power. The UV are inside a scanner so there are very near to the pcb. This is the reason that i use it for 8 sec not minutes. Now about soda solution i use the same with you 7...8 gr for 1 liter water. Today i used water with TUBOFLO but the same problems. The same with the spray. I believe that the photosensitive pcbs are not good, the same for the spray, because i use this method at least 20 years. Tommorow if i will have time i will try with paper and Iron. But i dont know what paper to use. I have not PnP paper. Many people use white paper from magazines. but where to find a white paper...... all are full.
Never mind........ i told that it is my good day (a lot of days are not my good)
My Regards
Now litle things for Ivconic.
When i tried to null a coil with oscilloscope and without resistor for load i had bigger indicator and some times i had selfoscillations (when the coil was very tight tune), so the results was bad. For me the best null with scope is to use one resistor parallel with coil (1..2k) and a resistor 5...10K in series with coil and scope. But... but ...but......... For me the problem is other. As i wrote before time sometimes i found that the best position for max sensitivity is a little open to the coil after a very good null. So if for example i have at the null a voltage of 5mv then the position that i have 10... 15mv was the best. I want to tell me your experience about this. Ivica or Max do you have tried the sensitivity of TGS with the coil not fine null? and if yes what do you saw.
Best Regards
Now litle things for Ivconic.
When i tried to null a coil with oscilloscope and without resistor for load i had bigger indicator and some times i had selfoscillations (when the coil was very tight tune), so the results was bad. For me the best null with scope is to use one resistor parallel with coil (1..2k) and a resistor 5...10K in series with coil and scope. But... but ...but......... For me the problem is other. As i wrote before time sometimes i found that the best position for max sensitivity is a little open to the coil after a very good null. So if for example i have at the null a voltage of 5mv then the position that i have 10... 15mv was the best. I want to tell me your experience about this. Ivica or Max do you have tried the sensitivity of TGS with the coil not fine null? and if yes what do you saw.
Best Regards
This is an interesting question, because Tesoro coils seem to be balanced with a 15mV residual signal, and they work fine.
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