MONOCOIL SUCCESS

[moodz]

Great news moodz.

Thanks foll all your efforts in field of monocoil applicability.

We need to rename "monocoil front ends" in "monocoil frends".

Thanks WM6 ... this work is being done so all ( or most ) monocoils that are already manufactured should work with this circuit. ( eg homemade and commercial coils ).

moodz

[moodz]

... add 260 pf to the circuit.



we add around 260 pf ( actually substitute heavy duty switch instead of low capacitance switch in blocking circuit ) ... very little degradation ... I am impressed. Maybe sampling at 5 microseconds now ( 120 microsecond TX ).

Ok so we wont be picking up the fine gold chains ...

moodz

[WM6]

Descrimination is available However it is via a two sample method which is not quite as "neat" as the single sample used on the differential coil.

However it is a vast improvement over conventional monocoil front ends.

moodz

Great news moodz.

Thanks foll all your efforts in field of monocoil applicability.

We need to rename "monocoil front ends" in "monocoil frends".

[moodz]

...more results.

We increase the Tx pulse length from 70 microseconds to 120 microseconds .... now there is some serious current and flyback running in this 0.37 ohm 18 inch coil.

The active blocker does its job with nearly 800 volts at the input
Still better than 4 usecs settling.

moodz.

[moodz]

Descrimination is available However it is via a two sample method which is not quite as "neat" as the single sample used on the differential coil.

However it is a vast improvement over conventional monocoil front ends.

moodz

[moodz]

The differential coil works swell but lots of folks have put time ( and money ) into the monocoil ( single inductance monocoil ) and I am sure that the time to make a major improvement in monocoil front end circuitry has arrived. So if you have an investment in conventional monocoils ( WM6 ) stay tuned.....

It turns out that not only is the circuitry very simple, uses active flyback blocking but also delivers every benefit of the differential frontend with the exception of descrimination
Although I just built the circuit so it could be in there somewhere .. we will have to see.

The coil is a flat basket weave 18 inch monocoil 16 turns of 2 mm2 wire and is driven by the UNIPI chip.
Demodulator sampling begins at 3 microseconds with a 70 microsecond transmit pulse.

Below is shot of the output of the active FB blocker prior to the demod / amp section Green Trace. The white trace is the mosfet gate drive signal.

moodz