Any mods for XLT?

[derick]

Hallo
I want slighty improved depth and stability in my XLT.It is "old" technology.My idea is replaced some transistors (chips) with low noise pieces.Also sharper discrim filters can being better.I have no schematic diagram.(similar Eagle only).Somebody try any electronic mods with XLT?

[detectoman]

good idea derik expander to major the xlt, i too had an xlt, these is good detector, but in warm of summer came little erratic and faulth right discrimination
may be change for other capacitors oldies, tubulars and mica, put insulation poliuretane in box, bateries alcaline etc ( caution whit excededd voltage ) remember experimentation always be risk

[mikebg]

Derick, the Spectrum XLT has well operating circuit diagram designed by Mark Rowan. Only TX section can be improved because operates with wrong principle. However such wrong principle is used also in newest designs. I made improvement of TX circuit diagram for CW metal detectors using P-I controller. However my design was for other project. It is not applicable direct for improvement of White's circuits, because use as current pump NPN bipolar transistor or MOSFET. It should be redesigned because in White's models is used current pump with PNP type BJT.
http://www.geotech1.com/forums/showt...eferrerid=2910
http://www.geotech1.com/forums/showt...eferrerid=2910

[derick]

Thanks Mike
nice idea rebuilt TX section.For me is no problem doing any electrical mod.But,theoretical info is not enought for doing it.Any concrete circuit changes for TX section are required.
Thanks again for theoretical help.

[mikebg]

Derick, take the breadboard. We will design and test a circuit diagram according the following block diagram.

[derick]

Any circuit mods or upgrades are no problem,but desing circuit diagram by myself is complicated for me.Principal schematics is nice,but can you desing a practical diagram?

[mikebg]

Let we see what is given for solution of design problem. (not "desing" :-)
Given is the circuit diagram of TX shown below. The operator can select from 7 operating frequencies given in table. Preferable is frequency #4. The circuit operates at two power levels: HIGH (at saturated Q11) and LOW. At LOW level is increased TX modulation index caused by change of coil height above conducting soil.
Given are three supply rails: +8V, COM (GND) and -5V.
We know also coil parameters and capacitance of TX tank circuit.
The driving signal needs enough high load resistance, for example 47K (see R26).

[derick]

Nice job
I will doing a separate pcb board for this circuit diagram (when components will arrived).The (-5v) is present in original XLT diagram?I havent xlt schematics,so where I can implant pcb will be a question.How do you thinking about increase depth with this "cube" tx mod?

[mikebg]

Nice job
I will doing a separate pcb board for this circuit diagram (when components will arrived).The (-5v) is present in original XLT diagram?I havent xlt schematics,so where I can implant pcb will be a question.How do you thinking about increase depth with this "cube" tx mod?

Derick, this is not the circuit of mod.
This is the existing circuit diagram of TX in your XLT that should be improved. The whole circuit diagram has name "Eagle" in the file with following link
http://depositfiles.com/files/88n8zxpc2

[derick]

Oh.sorry
thanks for files.How long will be way from design to real schematics diagram?

[mikebg]

Oh.sorry
thanks for files.How long will be way from design to real schematics diagram?

Derick, the road must be traveled by you, because I have no TX coil with White's parameters and I have no time and home conditions to experiment.
But you're not alone. Participants in this forum and I will help you. Furthermore, we have a model to copy; the attached here circuit diagram operates almost according block diagram shown in posting #5.

[kt315]

mikebg, all you offer is the wild jungle for me...

=====================================

guys, what your thought about step up converter in xlt? DIP-8 pin-in-pin 0,5A output current do you see around?

[mikebg]

mikebg, all you offer is the wild jungle for me...
guys, what your thought about step up converter in xlt? DIP-8 pin-in-pin 0,5A output current do you see around?

Anatoly, if the circuit diagram of Garrett given below belongs to your wild jungle, I will describe how it operates. I simply copy parts from well operating designs to realize the best operating block diagram.
My TX circuit (and TX of Garrett) improves GND elimination because dismodulates AIR signal.
What will improve your step-up converter? The AIR signal will remain modulated with the same frequency as GND signal when the height of coil changes.

[derick]

Hallo Mike
sorry for long time delay.I look to your schematics diagram.It means that I can prepare pcb and parts for this project according diagram?In your schematics garrett coil has a 10mh inductance.It will be good for XLT coil,or will be need any adaptation?What do you think about increase depth with this mod?Maybe 15-20%?
Thanks Tom

[derick]

Hallo,
according mods informations from Classic or IDX models I have a question.It can be improoved TX power section in XLT?As for as I know,the mod is touched resistor in emitter circuit of TX transistor.Ussually resistor 100ohm is changed to 47ohm.It can get more power to the coil.I look to the better schematic diagram from this forum (see atachment),but TX XLT circuit have another values and is not the same than older models.Another question is possibility increase power to the TX section from 5V to 8V.Something like "turbo" mode.Thanks for any usefull information.