IGSL

[Gwil]

That's excellent, many thanks. As you say, a good choice to be used with a home built detector and also looks like a good design to be copied by people who enjoy winding their own.

[Davor]

I do

Tx is resonant at 13kHz, but in F75 it is supplied via a kind of bandpass configuration to enable single-ended drive and soften the resonance. That way it is driven by a digital source, and frequencies are chosen via menu to avoid interference. Also the coil voltage is considerably higher than could be possible by direct drive.
Rx is softly resonant at over 20kHz. In that regard this configuration is quite classic. The only twist is a serial RC connected parallel to the coil, and its function is softening the resonance bump.

Of course, driving this coil this way is not the only possibility. It should work just fine in "Musketeer IGSL" Tx. Or the drive could be produced by a quartz oscillator and a counter. Say, 420kHz ceramic resonator and CD4060 counter/oscillator. This coil is used by a detector still in production, so this is a good choice regarding availability for many years to come.

[Gwil]

Thanks, that makes sense. Now I'm wondering what the coils are tuned to when they're plugged into the detector. Does anyone know?

[dbanner]

I'm confused (something that happens quite often). In the schematic shown in post #2167 both the Tx and Rx coils are labeled 12.9031kHz. Does this mean that with tuning capacitors connected across them both coils are tuned to the same frequency? As I understand it this gives better sensitivity but unreliable phase response, which affects ground balance and discrimination.

I think they were both tuned at same frequency in order to measure(calculate) the precise inductances and induced voltage in the Rx coil at null in full(equal) resonance of both coils, thus giving full parameters of the search head with cable and connector, but applied to use in device IGSL, would be tuned "off resonance"
Just my guess.

[Gwil]

I'm confused (something that happens quite often). In the schematic shown in post #2167 both the Tx and Rx coils are labeled 12.9031kHz. Does this mean that with tuning capacitors connected across them both coils are tuned to the same frequency? As I understand it this gives better sensitivity but unreliable phase response, which affects ground balance and discrimination.

[Davor]

Data of the MD F-75 sensor, right [ATTACH]43653[/ATTACH]


???

That's the closest I could get as well. To me it seem to be the sweet spot. Frequency, Tx inductance, Rx/Tx inductance ratio, Rx resistance... everything is just right.

[nikko10]

Data of the MD F-75 sensor, right


???

[Funfinder]

guys

again and again i reminder you. again and again. both shieldings must NOT be touched together one-to-one.
another way you get ELECTRIC ring closed EMI field. SPLIT THEM by izolation.

do not do me angry guys. do not do.

Correct! You need extra vertically and horizontally EM-field shielding at best with
AFC auto gain level adjustment to filter out the best possible signal-noise ratio!

https://en.wikipedia.org/wiki/Balun

This stuff meanwhile even all the new smartphone WiFi chips have inbuilt.

[Davor]

I believe F-75 coil is about the best choice for future IGSL projects. It is balanced at 13kHz.
I'll seek a cost-effective way to obtain such a coil, first and foremost for another project, but I'd like some experimenting with it. If someone may whisper a good word on my behalf at NEL, I'll appreciate it. My funds are running low.

[nikko10]

Tx is 14.5kHz and Rx is 16.12kHz.-

made a coil with such frequencies, the metal detector works very badly! It may be necessary on the contrary-the frequency Rx should be less than the frequency Tx ???

[nikko10]

The coils are isolated from each other by transparent tape! Well, the output of the shields of the coils, naturally, is soldered to the screen of the cable, but how else?

[kt315]

guys

again and again i reminder you. again and again. both shieldings must NOT be touched together one-to-one.
another way you get ELECTRIC ring closed EMI field. SPLIT THEM by izolation.

do not do me angry guys. do not do.

[nikko10]

I returned from the hospital after the infarction and immediately to the computer ... Thank you very much for the tips. Last time I forgot to put the sensor photo, with the data that I wrote before the imbalance was 40 mv. I'll try with Тх-14,5кгц, and Рх 16.12 kHz ... I really like the voice of the goals! I'll still finish it !!!

[kt315]

Davor here. you can ask him directly.

[Akhnoth]

Hello everobody,

Very good forum.

Is there anybody that can share the IGSL Musketeer Davor ver. 4 May 2017 Part List with current components.

Thanks in advance