IGSL

[der_fisherman]

Tuning of coils

Did you have any thoughts on "tuning" of coils for best response?

[ivconic]

Hi Ivconic,

I am getting close, just waiting on my SilverDog kit for IGSL with TGSL DIY search coils.
I don't want to make a mistake and you are by far the best source of information about IGSL.....(and probably TGSL as well as far as I am aware!!)

What is the best coil setup is confusing, different ideas and methods, just go for the best and deepest null? or follow Don's setup in TGSL 1010 Part 1? or here:-

http://www.geotech1.com/forums/showthread.php?t=15710

or can you recommend some other setup that you have recently found as being better? I am just a bit confused.......

Any further tips/changes that you can give me (us!) since the design for the PCB that SilverDog supplies was made?

I also have a thought about the coils, if the inductance for a coil ends up slightly out of tolerance than it should be, is there a way to add say a small trimmer capacitor or inductance across the coil to "tune" it into the correct frequency? That way the frequency of both the Tx and Rx coils could be setup to achieve the max signalFixed values could even be used in the search coil...........is my idea stupid?

If different coils were to be used, then the tuning must be made in the search head so that each coil would be "acceptable" to the electronics without major adjustment...
If there is some merit in what I am saying, is there anybody here (as well as yourself of course) that has spent some time and thought in this direction and can elaborate on my ideas better?

Thanks for your time and trouble and sorry to bother you again.....maybe I am thinking too much and it won't be a problem as I imagine.....

regards

Andy

Dfbowers's setup seems good, except use of USB cable.
So i am suggesting you to obey his wiring method inside the coil housing, BUT instead USB cable you better use Belden. I gave photo of it.
The rest... everything is already explained well.
So far we all respected inductances 6mH for TX and 6.5mH for RX, and those working just fine.
But since you are just starting to make your coil; why don't you try with 5.7mH for TX and 6.2mH for RX? Because those are inductances at most original Tesoro coils.
Residual voltage at few original Tesoro coils i measured so far, was exact 4mV (AC 200mV range on multimeter) , measured with this one:

http://www.victorelectronics.com/specifications/vc9805a_specs.htm

Reason i am posting exact model of instrument is because of the accuracy issue at similar cheap instruments.
You can't expect , nor to rely on, measuring results i had with VC9805A+ in case you perform same measurements with different kind of instrument.
So my "~4mV" doesn't necessary need to be your "~4mV", if you understand what i mean?
So you better perform frequent coin checks in air, during process of nulling. Along with coin you do use other materials too; ferrite rod, iron, etc..etc...
Because without such checks you may end up with situation to have "~4mV" and still not so good performances of coil...
That's because we do not use same measuring standards and instruments...

[der_fisherman]

Hi Ivconic,

I am getting close, just waiting on my SilverDog kit for IGSL with TGSL DIY search coils.
I don't want to make a mistake and you are by far the best source of information about IGSL.....(and probably TGSL as well as far as I am aware!!)

What is the best coil setup is confusing, different ideas and methods, just go for the best and deepest null? or follow Don's setup in TGSL 1010 Part 1? or here:-

http://www.geotech1.com/forums/showthread.php?t=15710

or can you recommend some other setup that you have recently found as being better? I am just a bit confused.......

Any further tips/changes that you can give me (us!) since the design for the PCB that SilverDog supplies was made?

I also have a thought about the coils, if the inductance for a coil ends up slightly out of tolerance than it should be, is there a way to add say a small trimmer capacitor or inductance across the coil to "tune" it into the correct frequency? That way the frequency of both the Tx and Rx coils could be setup to achieve the max signalFixed values could even be used in the search coil...........is my idea stupid?

If different coils were to be used, then the tuning must be made in the search head so that each coil would be "acceptable" to the electronics without major adjustment...
If there is some merit in what I am saying, is there anybody here (as well as yourself of course) that has spent some time and thought in this direction and can elaborate on my ideas better?

Thanks for your time and trouble and sorry to bother you again.....maybe I am thinking too much and it won't be a problem as I imagine.....

regards

Andy

[ivconic]

That just demonstrates that when metal detecting, Ivconic never needs to take a shovel or spade with him!!!! Less to carry!!

[der_fisherman]

IMHO you need to trim your nails.

That just demonstrates that when metal detecting, Ivconic never needs to take a shovel or spade with him!!!! Less to carry!!

[ivconic]

Just do this:

[ivconic]

Was there anything interesting in the electronics for you Ivconic?

I've seen Anker project many years ago!
I've seen few versions.
Also have one pcb made for some of those...
Anker is very old project.
We all here (older members) are already know about Anker...for long time.
What is done at Anker - is not suitable to be done at IGSL...

[der_fisherman]

Was there anything interesting in the electronics for you Ivconic?

[ivconic]

This is why i posted it here. Point is, some other designs try to achieve similar results like IGSL using other approaches and methods to solve same issues. My intention was constructive, not offending, sorry. (over and out)

I see.
Not offended at all, of course.
Just tired to see various "ankers, strums, volksturms.. clonepi....skifpi..." and similar EVERYWHERE, spread like bad seed.. , at most of the topics here on these forums.
Enough is to start new topic named "Anker xyz" and later just to put reference (link) on it here. Of course with explanation; why that link is provided...
That's how i would do...
At least your post is not so annoying... but gigantic post made by der fisherman is really scary!
That's why i complained..

[der_fisherman]

Sorry, I forgot where I was, you are completely right......it does not belong here.

Can someone put my post in a better place? Please?

(I look at many blogs here, one after the other, trying to get a "good education" so to say......, and I simply forget where I am sometimes.....)

regards

Andy

[Tepco]

Back to IGSL..
how about that mixed mode audio?
It can be applied on few ways...
I am trying to find out the simplest one.

This is why i posted it here. Point is, some other designs try to achieve similar results like IGSL using other approaches and methods to solve same issues. My intention was constructive, not offending, sorry. (over and out)

[ivconic]

Take a careful look at design approach of Russian made Anker 50 detector

http://vash-ru.net/anker/a_50m.shtml

Discussed here:

http://www.md4u.ru/forum/viewforum.p...3e7592eea99234

The "modernized" version:

http://fandy.vov.ru/Anker/Anker.html

3 channel "single derivative type" design, specific approach to GEB circuit etc, bit different from Tesoro.

???
I don't see why you posted it here?
Shouldn't you start new thread?
What is the point?
What that has to do with IGSL here?
...
Der fisherman, also there is no reason for your gigantic post with approximative translations... about something that has nothing in common with subject here - IGSL???
...
I suggest administrator to replace that in new topic.
I am not interested to see no "ankers" of what so ever here in IGSL topic...sorry!
Aren't we already annoyed enough with various "ankers, sturms, volksturms...etc..etc.." everywhere on these forums?
Those are simply everywhere...under every possible topic?!
Please... not again!
Please don't do that here!

[der_fisherman]

Russian IB Machine

Take a careful look at design approach of Russian made Anker 50 detector

http://vash-ru.net/anker/a_50m.shtml

Discussed here:

http://www.md4u.ru/forum/viewforum.p...3e7592eea99234

The "modernized" version:

http://fandy.vov.ru/Anker/Anker.html

3 channel "single derivative type" design, specific approach to GEB circuit etc, bit different from Tesoro.

I put the website through a machine translation, mostly OK I think:-


This detector is an improved version of the instrument Anker - 50. The scheme has been refined and simplified, were taken into account customer feedback and incorporates more modern components. In addition , the instrument more reliable and economical.

The main differences from the model Anker - 50:

Applied external excitation circuit of the sensor oscillator
In the output stage of the generator used in MOSFET- transistors
The output signal generator used to generate the field , the formation of supply voltages and power op amp buffer probe
As applied to two-wire connecting cable microphone cable
In the whole scheme uses only one common voltage regulator

Main technical characteristics:

Sensitivity to 5 kopeks coin . in the air - 45 cm. 18.2mm 2.6 grams



Search head - coaxial - planar , diameter 25 cm
Principle - Induction balance .
The number of channels of signal processing - 3.
Mode - dynamic .
Power - 12V , 1.3 Ah
Current consumption - 150 mA.
device can also operate on low voltage in the 7.9 volts, just replace the voltage regulator roll on roll 8a 5c.

Description of the scheme.
master oscillator

Performed on the inverter ( 561LN2 ) and stabilized quartz 4 MHz . After dividing the counter ( 561IE16 ) that the operating frequency of the device - 7.8 kHz. On the same counter signals are removed to form a sound indication (243 Hz - low-pitched signal and 974 Hz - the signal of high -pitched)

power Amplifier

The five inverters ( 561LN2 ) acts as a driver that controls the MOSFET - transistor output stage. Further amplified by the power meander comes to a resonant circuit sensor and a transmitter , feeding the buffer op amp probe. In addition, the same signal feeds the converters that form the voltage -U to power the analog portion of the circuit and two voltage doubling power amplifier for synchronous detectors. Meals high voltage amplifiers diabetes can increase the operating range , and ultimately , the stock of "survivability " of the instrument when imbalance sensor , arising out of - the changes in temperature.

shifters

Series with the resonant circuit includes a low impedance sensor resistor (1.5 ohm ). Harmonic signal is taken from a differential amplifier ( OU1 ) and served on the knot shifters ( Dy2 -180 gr, 90 gr - OU3 , OU4 - 270 g chips 1401UD3 ). The output signals are phase shifters to compensate for the residual signal imbalance sensor and to generate control signals synchronous detectors .

To convert analog signals into digital harmonic required for key management of synchronous detectors are comparators (LM339).

Receiver
Useful signal, the selected resonant circuit receiving the sensor enters the buffer stage (DU UD608 ) , which serves to match the high output impedance of the circuit with a low -impedance summing input amplifier. Such circuitry can significantly reduce the interference caused by the deformation of the cable connecting the sensor with electronics.

The input

Completed at OU1 ( 1401UD3 ) included in the scheme adder. On its inverting input the signal arrives from the sensor , as well as compensating signals to phase shifters . At the output of op amp , these signals are summed .

Dale, compensated and amplified signal is fed to the controlled phase shifter, through which the balance of the soil. The output of the phase shifter forward and inverted inverter ( OU3 1401UD3 ) signal is fed to the inputs of synchronous detectors .

synchronous detectors

Performed on three multiplexers (CD4053), which outputs through the integrating RC- chain fed to the non-inverting input of the amplifier synchronous detectors , and then , after amplification by dividing capacitors, cut off not carrying a constant component of information , fed to the inputs of channel amplifiers.

channel amplifiers

Identical , are collected under the scheme the non-inverting op amp (LM324) in the chain of environmental protection include capacitors, limiting the gain in the HF range .

The top two channels determine the presence of metal and compensate for interference from the influence of soil and deformations of the sensor, the lower channel determines the type of metal ( black - the color ). Adjusting the initial DC offset of the two upper channels by using the " Threshold" .

Two series-connected transistor ( KT3102 ) form a "soft" analog logic elements "AND" and pass the signal on the output only if their inputs come at the same time half-wave of positive polarity that occurs when the presentation to the sensor to the metal object.

The third channel controls the comparator, whose output signal depends on which side is the signal change .

Modulator, the audio amplifier

Signal from the load merged emitter follower is modulated by the multiplexer (CD4053) with a frequency determined by the state of the comparator and the third channel is fed to the output amplifier, operating in switching mode . Load the output stage the sound is a speaker with impedance of 100 ohms.

Block Diagram audio tone

The task of fixing the circuit is selected audio tones to indicate the end of time , ie as long as the sensor is located next to a metal object. It consists of a rectifier alarm, the comparator ( OU4 1401UD3 ) key and a storage capacitor (0.01 m ).
When a sound wave rectified AC voltage comparator switches , which by means of a multiplexer (CD4053) breaks control circuit mulpleksora?? second , choosing the appropriate tone of a sound signal.

Thus, selected at the initial time of appearance of the alarm tone persists to the end of time by maintaining a sound indication of the charge storage capacitor.

establishing

1. Networking is made in stages as follows:

Ensure reliable operation of the oscillator , and if necessary to clarify the capacitance ( 330pf ).Then check the operation of the counter and make sure you have a clean square wave at the output of output stage transistors with a frequency of 7.8 kHz and 243 Hz signal display and 974 Hz. Check job site power converters , the polarity of electrolytic capacitors.

2. Customize exactly to the resonance circuit generating the sensor to verify the work buffer power converters Shelter, check the polarity of electrolytic capacitors.

3. Customize exactly to the resonance circuit receiving the sensor. To make compensation for the sensor. monitoring the signal at the output of op amp buffer . Setting to produce a "native" cable -connected coils screens set screw fixing probe away from metal objects.

4. Configure node shifters , make sure you have at the exit OU1 harmonic signal (the presence of a small "step" is permissible), then set the phase shift 90g . phase shifter on OU3 and then test the inverters Dy2 OU4 . Check operation of the comparator (LM339).

5. Check operation of the input amplifier and controlling the output signal to produce an accurate compensation OU1 sensor trimmer shifters ( 47k ). Check the availability of signals at the outputs Dy2 OU3 .

6. Reducing the band rejection to zero, connect the oscilloscope to the output synchronous detector of the first channel . Produce a balanced soil , using as an equivalent piece of iron . When moving the iron around the sensor at a distance of about 20cm and rotating wiper to find the balance point of the soil. Before the end of the
instrument settings do not change the position of the engine. After setting the ground balance for average band rejection of the soil.

7. Ensure proper phasing of the signals at the outputs of synchronous detectors . When properly configured, the signal must be changed as follows:
channel 1 - up ferrite , iron up the coin up .
Channel 2 - ferrite down , the iron up , the coin up .
Channel 3 - ferrite down , the iron down , the coin up .
The first two channels are the same, no matter what the result of which channel belongs.
For phase inversion of all the channels at the same time you can swap the connection point to the low-resistance resistor (1.5 ohm ) differential amplifier OU1 .

8. Check operation of the channel amplifier and comparator channel discrimination ( OU4 ), modulator, amplifier and output circuit block audio tone . Check the total power consumption device , the quality of work and iron notch discriminator.Check otsutvie parasitic excitation at the moment when the sound channel . The reason for this phenomenon may be a bad PCB layout apparatus , the presence of "current loop " in the chains of the common wire . With proper layout of the power of the circuit ( the output stage is the causative agent and the output stage audio amplifier ) must be grounded at one point.

improvements

You can:
complete diagram of the device low battery indicator on your taste.
install a connector for headphones.
miniaturize the instrument board using SMD - assembly instead of a voltage regulator such as roll 8a put a better stabilizer that works with a smaller drop , it will increase the run time of the device (battery life) want to try switching regulator with high efficiency
transfer to low-voltage device powered by four " AA- " batteries, incorporates the DC / DC converter with built-in stabilizer produce a different size sensor with a different way to compensate.

[Tepco]

Take a careful look at design approach of Russian made Anker 50 detector

http://vash-ru.net/anker/a_50m.shtml

Discussed here:

http://www.md4u.ru/forum/viewforum.p...3e7592eea99234

The "modernized" version:

http://fandy.vov.ru/Anker/Anker.html

3 channel "single derivative type" design, specific approach to GEB circuit etc, bit different from Tesoro.

[ivconic]

Back to IGSL..
how about that mixed mode audio?
It can be applied on few ways...
I am trying to find out the simplest one.