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Thanks davor for the help, I will try to, ISGL I could work it makes me happy, because, I do not have paypal so can't buy a kit from silverdog and cost to send keindonesia can 3 or 4 times as much for an entrance fee of up to up to me so I can just create their own pcb Board
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Hello Davor.
Your idea look´s very good. If i understand it right, with seperated AMPR you don´t loose the searching-deep through adjusting the GEB.
What coil you still want to use? Your "FKK"-Coil? Or an original Tesoro-Coil?
I think we need a stronger TX-part and than it´s time to make a new PCB.Comment
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@liekwang, I understand your trouble. My country only recently joined EU and since then my mail orders are much cheaper. At least those from EU.
@mschmahl, there is one more detail I have to fix prior to calling this a success. In beach hunting GEB, the one near 0°, there is a phase reversal for Fe targets in a GEB channel, and sensing Fe is lost. Coloured metals will not be affected, but to have Fe as well I'll have to make some absolute value circuit, and it is a complication.
As for the coil, it makes little difference FKK or not. I prefer FKK. It requires balanced input circuitry. If one is happy with half-way-there a simple differential connection op amp will do. It took me a while to realise that asymmetric coil loading in a differential mode is OK, as long as common mode observes equal impedance on both inputs, so the original connection is in fact OK, at least balance-wise. A real step forward from there is using BJTs on input to significantly improve input noise (some 10dB improvement). Half-way-there would require only slight resistor values change to optimise for LM833 noise performance, which is some 3dB better than right now.Comment
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?Hi davor CD4204 diodes 4148 under or U2 should I jumper to U2 to PIN how I wear the the PCB petravka ISGL musketeerComment
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At Petravka PCB you have two square pads connected to diodes, and 3 pads connecting various outputs of 4024. You have to put jumpers between each diode and any of the 4024 outputs. If you don't like the tone you get, simply use the other output.Comment
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?Davor I don't have positive voltage TX connected to BC327Comment
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Hi,
I measured my Musketeer coil with Rx preamplifier. Here are my results. I have some questions .
What is the right Tx-Rx phase shift in the case of IGSL Musketeer coil ? Is it 20 degrees as in case of IGSL TGSL coil ? I can see, that for 20 degrees for my coil Tx frequency should be 8,8 kHz. Bigger phase shift means closer Tx Rx resonance. I can see, that phase shift 90 degrees means TX = Rx resonance . Has the bigger phase shift (closer Tx Rx resonance ) sense on sensitivity of the coil ?
My next question is : everyone talk about milivolt coil nulling. Is this voltage measured on the output of Rx preamplifier, or is it recalculated to input of preamplifier ( Output of premplififer = preamplifier gain * input mV ) ? What is good nulling result on the preamplifier output ?
http://www.geotech1.com/forums/showt...638#post152638 post#8
I am asking you, because I still can not reach air detection distance +30 cm ( my max distance is still only 20cm ) for one euro
Robert
measure.pdfMyIGSLmusk-Ph-Volt.pdfComment
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nullvoltag can directly measure on rx coil
i think somethnik under 6mv is ok
at 0mV your coil is hardly undernulled
1nf = 1000pf1mH=1000uH TX uH TX CAP pF TX freq khz RX uH RX CAP pF RX freq khz rel TX - RX L*C TX L*C RX 1000 330000 8,76 14700 14700 10,826876 1,235775655 330000000 216090000 899 330000 9,24 14000 14700 11,0942466 1,200643656 296670000 205800000 918 330000 9,14 14300 14700 10,9772565 1,200470865 302940000 210210000 2000 150000 9,19 14000 14700 11,0942466 1,207363221 300000000 205800000 Comment
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Good!Originally posted by sini View Post
8.3kHz to 8.8kHz is the proper range in case TS1000 is used with IGSL.Comment
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Phase shift will be fine in 10-30° range. It also somewhat depends on the way you connect a coil to a preamp. Closer to 30° will make your discrimination ranges more meaningful because in IGSL it is also the amount of phase ranges overlap. Going too far will make your GB unreachable (it has a limited reach)Originally posted by sini View Post
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Closer to resonance will improve input referenced noise a little. Theoretically you could reach even below 1nV/sqrt(Hz), but at a cost of very touchy phase transition and hectic behaviour of a device. Instead you have some ~8nV/sqrt(Hz) with usual setting. Replacing 47k/220k resistors with 1k5/100k would reduce input referenced noise to ~5nV/sqrt(Hz) without too much coil loading. Connecting a coil to a non-inverting input directly (other end to signal ground), and replacing resistors in inverting branch to 470ohm/47k would reduce input referenced noise below 4nV/sqrt(Hz), which is fine because LM833 by itself has ~4.5nV/sqrt(Hz).
Whatever excess gain you have in the system will present itself in form of chatters, and you'll compensate it with Disc.Sens. pot. In case you don't have any chatters, you can crank up system gain and achieve more depth.
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Your schematic of a measurement is very correct. It is also correct to measure a coil nulling directly in case you have proper oscilloscope probes. In case you are restricted to beans and bacon solution using a PC scope, a solution with observing a preamp output is more correct, as it ensures proper coil loading, and also supplies a low impedance output for PC soundcard input. It would also show signal level on preamp output, which should not exceed ~300mVpp. I'm attaching your pdf in a picture form, it is very nice.Comment
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Hi invonic I'll assemble again until isgl could work. And it makes me happy to help anyone on this forum who has a file of the same PCB Layout Board with black and white layouts silverdog version and component parts of upper side JPG file thank youComment
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?I am just a beginner with electronics so not so familiar with what what the signals Rx and TX and I was not familiar with the form osiloscop and signals. I can only assemble with what is seen with pcb layout and components on the top because I wanted to learnComment
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It is OK, but to help you we'll need some simple input of what you need. Do you need a B&W printer ready PCB layout?Comment
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?Yes davor I need upper and lower, layouts, such as the surf I can do it and it works well but I don't like the overly sensitive to soil. Thanks davor for your helpComment
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The best way to obtain almost every layout on this forum you need is to install a Sprint Layout viewer (free) at http://www.abacom-online.de/uk/html/sprint-layout.html (scroll to the bottom of page)
You'll be able to print whatever layer you need in 100% quality, just like this one (unzip it first)...Comment
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