Coil for any of the detector. Very simply.

[FOMA]

How to make a sensor to any detector? Very simply.
Do generator according to this scheme:



Measure the impedance and resonant frequency of the windings in the sensor.



Do winding for your sensor. Windings can be of any size. We must have the same resonance frequency and approximately resistance.


When the windings are ready, they should be put in the ready housing and make balance.
Balance do You know how.

For detectors E-TRAC and Explorer need litz wire. I do it like this:



Here's the coil to the Explorer SE :



To this theme more pictures here:
http://www.reviewdetector.ru/index.p...pic=80022&st=0
http://www.reviewdetector.ru/index.p...ic=155140&st=0

[satdaveuk]

Thanks for sharing never thought of using polystyreen, alot of very useful imformation

Very greatful many thanks

Regards

[TH Jim]

Hi,

Do you have any more information on the circuit? like the min/max values of inductor that can be measured or how the inductor value is related to frequency ??

Regards, Jim.

[satdaveuk]

Hi,

Do you have any more information on the circuit? like the min/max values of inductor that can be measured or how the inductor value is related to frequency ??

Regards, Jim.

Hi jim
If you build the coil tester I put on here 2-3 days ago under tools its simple uses common cheap transistors, most of the bits were out of my junck box, it will oscillate lwr/higher than the limits of any metal detector coil and more if you change the 2n2907 to a BR99 which are old and around £7 it will take you up into GHZ without changing any other component.
If your using those frequency although the PCB I designed has ground plain I strongly sugest you mount or cover in a screening can for ovious reasons
The BR99 was commonly used in old varicap TV tuners, so if you got some of those laying about your laughing.

Regards

[FOMA]

Hi,

Do you have any more information on the circuit? like the min/max values of inductor that can be measured or how the inductor value is related to frequency ??

Regards, Jim.

Generator excites circuit on the frequency of the resonance. The frequency depends on the capacitor 10H and the inductance of the coil. Because the capacity of 10H great, the cable capacitance and the capacity of the windings does not matter. Data can be very accurate. Much more accurate than measuring just inductance.



So you can do the sensors Tesoro, Fisher and other detectors. Here, for example, data on the sensor old LOBO: RX-51om f=14,65kHz Tx-11,9om f=17,88kHz.


http://www.md4u.ru/forum/viewtopic.p...2681&start=350

[TH Jim]

Hi guys,

How do we extrapolate the inductance from a frequency measurement?

I have tried doing this with colpitts oscillators in the past by rearranging the equation

Fosc = 1/2pi*sqrt(L*C)

But it was never accurate enough, different values of C would give different frequencies which when put into the formula would give different values for L. Coil calculators seem easier and more accurate in the absence of an LC meter.

I have recently resided myself to the need to buy a decent inductance meter as there seems to be no other option for accurately knowing the value of a coil - If anyone can enlighten me to some other method I would be grateful

[FOMA]

When You measure the inductance, that every measure will be different. One LC- metr will give one value, another -the other. But with my generator frequency winding will be the same always. There is a cable or no cables- it does not matter.

[Helikeon]

FONA, thank you for a very informative and useful contribution.

[mikebg]

FOMA, your table in post #5 shows very low resistance of RX winding for all coils. That means useless increased weight of metal. Are you sure that the values are correct?

[homefire]

Hi guys,

How do we extrapolate the inductance from a frequency measurement?

I have tried doing this with colpitts oscillators in the past by rearranging the equation

Fosc = 1/2pi*sqrt(L*C)

But it was never accurate enough, different values of C would give different frequencies which when put into the formula would give different values for L. Coil calculators seem easier and more accurate in the absence of an LC meter.

I have recently resided myself to the need to buy a decent inductance meter as there seems to be no other option for accurately knowing the value of a coil - If anyone can enlighten me to some other method I would be grateful

L= R*sqrt(3)/(2*pi*f)

[TH Jim]

Thanks Homefire.

In the equation L= R*sqrt(3)/(2*pi*f) What value does R represent - coil resistance?

What value is the 10H capacitor that is paralell to the coil in the schematic?

Will probably give this circuit a try.

Regards Jim.

[FOMA]

FOMA, your table in post #5 shows very low resistance of RX winding for all coils. That means useless increased weight of metal. Are you sure that the values are correct?

I'm sure. I myself did measurement. Coil 5 " has a lot of resistance TX and low resistance RX. This coil emits less than the electromagnetic field, and is intended for very junk sites.

[FOMA]

Thanks Homefire.

What value is the 10H capacitor that is paralell to the coil in the schematic?

Regards Jim.

The capacitor is needed for the formation of the path to be acceptable frequency. All frequencies in the table are made with a capacitor 10H. If there is another capacitor, the frequency will be others.

[homefire]

The RED Capacitor is what ever value you use!

Lower value for higher freq.

Higher value for lower freq.


It's a whole lot easier to use this! LOL

http://www.whatcircuits.com/lc-reson...cy-calculator/

[kliner]

Homefire
My antivirus says there is a trojan at the page you have posted!