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NOTE:
Estban's pasive receiver (mag.preamplifier) work with phase opposite signal at 180 el.degrees. To achieve no-signal mode, ferrite input LC tank circuit must be tuned to sense opposite phase of stimulus signal (ferrite osc.), so the net phase is zero or in other words ferrite mag.preamplifier output is hold balanse, real null. 1st step is nulling stimulus signal, multiturn sens potentiometer at maximum, very bright stimulus led and retune in opposite side untill the stimulus led is off.
This one is a point of maximum sensitivity but not useful because disbalance mag.preamplifier and led is bright. After finding correct position for magnetic preamplifier pcb and 1 turn coupler coil, passive receiver enter near zero net phase. Critic null point is achieved retining again sens potentiometer untill both leds off. This is a magic null point where lrl is extremely sensitive, To be known catch hold exact null is extremally difficult step, because we need electrical and geometrical balance in only one point at micron precision.
Halo effect from gold target or silver one, disturb mutual net phase eiher from stimulus (ferrite osc.) or ferrite LC tank or both. This avalanche disbalance act up amplitude rise at 2nd dc amplifier stage (rise voltage after diode rectification) and trigger audio beeper generator. Target detected.
Stimulus freq. 80KHz is probably (.99) correct for Esteban background, but sure not good for us at East Balkan.
Nulling could be at any frequency but not all frequencies carry on Halo effect signal. LRL detection belong to class of solving NP-hard problems. So only the real LRL masters like Alonso, Esteban, Geo, Morgan,... could bite up the real null.
"A Solid Roman gold coin signal is gone again! "
Best Regards
Dragan the Highlander
South Serbia
East Balkan
repost.....
NOTE:
Estban's pasive receiver (mag.preamplifier) work with phase opposite signal at 180 el.degrees. To achieve no-signal mode, ferrite input LC tank circuit must be tuned to sense opposite phase of stimulus signal (ferrite osc.), so the net phase is zero or in other words ferrite mag.preamplifier output is hold balanse, real null. 1st step is nulling stimulus signal, multiturn sens potentiometer at maximum, very bright stimulus led and retune in opposite side untill the stimulus led is off.
This one is a point of maximum sensitivity but not useful because disbalance mag.preamplifier and led is bright. After finding correct position for magnetic preamplifier pcb and 1 turn coupler coil, passive receiver enter near zero net phase. Critic null point is achieved retining again sens potentiometer untill both leds off. This is a magic null point where lrl is extremely sensitive, To be known catch hold exact null is extremally difficult step, because we need electrical and geometrical balance in only one point at micron precision.
Halo effect from gold target or silver one, disturb mutual net phase eiher from stimulus (ferrite osc.) or ferrite LC tank or both. This avalanche disbalance act up amplitude rise at 2nd dc amplifier stage (rise voltage after diode rectification) and trigger audio beeper generator. Target detected.
Stimulus freq. 80KHz is probably (.99) correct for Esteban background, but sure not good for us at East Balkan.
Nulling could be at any frequency but not all frequencies carry on Halo effect signal. LRL detection belong to class of solving NP-hard problems. So only the real LRL masters like Alonso, Esteban, Geo, Morgan,... could bite up the real null.
"A Solid Roman gold coin signal is gone again! "
Best Regards
Dragan the Highlander
South Serbia
East Balkan
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