Coils

[BJ]

Hello people!

Does anyone have any info on the (VLF)pinouts
of the search coils of the larger manufacturers?

Im looking for pinouts of Bountyhunter, Tesoro, whites, Fisher, etc! Why? Because i like to adapt my own design to several of these!

Aprechiate any info submitted!

Regards
BJ

[Rick S]

BJ,
Try search on #5 and look at 5.02.01 Rick S. The White's GMvsat coil drawing and pic of inside the coil housing.

Rick S

[Dave J.]

In my opinion, the searchcoils best adapted to hobbyist experimentation are the Tesoro Lobo Supertraq and the Fisher CZ coils. Both are single-ended transmitter and receiver with no transmitter resonating capacitor. Eectrically they are somewhat similar, with transmitters somewhere around 1 mH, and receivers somewhere in the range of 10-15 mH. The Lobo loops are balanced for the Lobo of course, about 17.5 kHz, but can be used somewhat outside that range. The CZ coils are balanced in the range of 5 - 15 kHz. Of course these are induction balance searchcoils for VLF use and are not suitable for pulse induction. The CZ coils have lower resistance and therefore higher Q than the Lobo coils, but the Lobo coils are available in wider variety.

In order to determine the pinout and actual inductance, use an ordinary LCR meter. Determining which end is signal and which is ground can be a little more complicated unless you are able to slip the shell off the connecter and determine wiring by inspection.


--Dave J.

[BJ]

That was a rather complicated coil, does it
really perform any better then a well done ordinary pinpoint coil(omega loop type inside)??

Thanks for the info anyway Rick!

Reg
BJ

[BJ]

BTW, when we are talking about "coil
resistance" what parameter are we exactly
talking about? The impedance or the reactance
or the DC reistance or all together at a
given frequency?

I mean the reactance is important in the sence
of knowing the load for the TX driver amp at
a given frequency.

And forgive me for this question, but im used
to mH mm, inch etc, so what does eg, 26AWG
stand for?

26 Automated Wolksvagen in GB?? :-)

REg
BJ

[Rick S]

BJ,
The Goldmaster series coils have to be within the design limits for the circuit. The concentric looks complicated, but it is easier than making a DD coil. The info is there on making a coil for the GM series. Good luck.

Rick S

[Carl]

Winding, followed by pins (pos,neg), followed by inductance, and finally DC resistance.

White's Spectrum
Rx 1,2 36mH 123 ohms
Tx 4,5 540uH 1.4 ohms

White's 6B
Rx 1,2 16mH 35 ohms
Tx 4,5 1.7mH 7 ohms

White's DFX concentric
Rx 1,2 13.8mH 36 ohms
Tx 4,5 540uH 2.7 ohms

White's DFX DD
Rx 1,2 14.2mH 55 ohms
Tx 4,5 680uH 3.5 ohms

Tesoro concentric
Rx 3,4 6.2mH 22 ohms
Tx 1,5 5.7mH 22 ohms

Tesoro early Lobo DD
Rx 1,3 1.35mH 12 ohms
Tx 2,4 10mH 55 ohms

Fisher CZ
Rx 1,2 6.8mH 30 ohms
Tx 3,4 1mH 2.8 ohms

Most numbers are based on several coil measurements, including different size coils for a given coil type.

The White's 6B coils are really easy to find, and come in a huge range of sizes.

- Carl

[Dave J.]

Resistance is measured at DC, or at 1 kHz which is nearly the same thing. Searchcoils are almost always designed so that the AC losses are small compared to the DC losses.

The AWG system is like decibels. Every increase of 3 in wire gage corresponds to a doubling of wire resistance (a halving of wire cross-sectional area). AWG 18 has a diameter of 1.02 millimeters, and a nominal resistance (annealed copper) of .0209 ohms per meter at 25 degrees C. From that, all AWG diameters and resistances can be calculated.

--Dave J.

[BJ]

Hmm, it seams that the tesoro lobo RX TX values are swapped?

Besides does this mean that those coils you
mentioned here is differentially driven and
differentially recieved?

Or does it mean that all are single driven and recieved and coil ends to separate GND's?

Besides,what kind of TX driving is most common
a tri/sin funkgen or the "wandering" colpitts?

Thanks for the info anyway Carl!

Reg
BJ

[Carl]

Yes, I probably got the Lobo pins swapped.

Far as I know, everyone is driving coils single-ended. Most use basic Colpitts oscillators, some pnp with the coil grounded, some npn with +V on the coil (e.g., White's). This is true for single-freq. designs. Multi-freq use pulse waveforms, probably generated by the micro.

- Carl

[Elron]

i've never heard of a omega loop can anyone tell me what that is?

[massimo]

Yuo can see Magnum project in the site, magnum use "omega" design coil.
regards
max

[Milen Sheringov]

Hello

Fisher 1210
Rx 6,48mH / 15,3 Ohm
Tx (1,64mH / 7,7Ohm) + (1,62mH / 7,5Ohm)

Fisher 1266
Rx 10-10,4mH / 38,2-39,3 Ohm
Tx 2,14-2,2mH / 4,7-4,9 Ohm

Fisher Quick Silver
Rx 6,69-6,7mH / 31-32Ohm
Tx 0,945-0,960mH / 3-3,1Ohm

Regards