White 3900D

[kt315]

Blue plot is output of LM393.(ltSpice)
---
393 reacts just on knob RESET. in your plot its like a generator. bad.

[kt315]

translate a text on sch. on output of the 393:

in standup logical 1 (H - high level, near +E)
closed S2 (S2 is knob RESET) gives logical 0 (L - low level, near -E)

[MartyJ1963]

Do you have your final layout in Sprint please DB?,,Thanks,,Marty

[dbanner]

Blue plot is output of LM393.(ltSpice)
---
393 reacts just on knob RESET. in your plot its like a generator. bad.

The blue plot is the output of U3/1. The reset switch toggles U3/2 output to HIGH/LOW. LM393 is a dual comparator chip.

I should have made that clear before, so thanks for pointing that out.

The output of U3/1 is the gating pulse which is supposed the provide a balanced signal to the inputs of the differential amplifier U2/1 of LM324.

[dbanner]

Do you have your final layout in Sprint please DB?,,Thanks,,Marty

.
Sorry folks, I uploaded the wrong file

Here is the final sprint layout. I am etching my pcb today. I'll show pics of the outcome, whether good or bad.

[kt315]

good start point to begin learning non-motion schematic https://www.ebay.com/itm/Metal-detec...4df4%7Ciid%3A1

[MartyJ1963]

Hi all,,,,Any progress yet DB? Thanks,,Marty

[kt315]

whites had fully changed the coil balancing methodology. i told that many times. there is NO PRIMARY RX vs TX phase aspect.
NOT EXISTS. there is sure FULL ZEROING, to microvolts residual value on RX.
you CAN NOT set the phase if you see on your o-scope screen NOTHING, just something of smeared line on the noise level.

[dbanner]

Hi all,,,,Any progress yet DB? Thanks,,Marty

.Not yet, things are moving slowly.
It is not so easy for me these days, I have a lot on my plate to deal with at the moment. Hopefully I'll have something to show on the weekend.

[MartyJ1963]

Ok DB,,,Thanks,,,Just wanted to know how things were with the PCB before I started etching,,,You said to wait so hopefully all goes well with your board,,,Regards,,Marty.

[sayan1345]

Hi DB
can you ad the GB to this circuit

[kt315]

GB to this schematic is nonaddable.

[dbanner]

whites had fully changed the coil balancing methodology. i told that many times. there is NO PRIMARY RX vs TX phase aspect.
NOT EXISTS. there is sure FULL ZEROING, to microvolts residual value on RX.
you CAN NOT set the phase if you see on your o-scope screen NOTHING, just something of smeared line on the noise level.

I refer to the Tx/Rx tuned resonances. If both Tx and Rx are tuned to the same resonances, there is maximum sensitivity of the coil (air test), but there will be poor performance due to the dynamic effects of the soil.
However, if the Rx is tuned to resonance at a specifically selected "off resonance" frequency, There is increasing phase shift and the dynamic effects of the soil is weaker by several orders of magnitude compared to the static effects.
There is a phase shift between the the Tx and Rx in Whites older loops. BECAUSE THE COILS ARE SO BALANCED TO SUCH PARAMETERS, AND NOT TO PERFECT RESONANCE.
The reason for the frequency seperation is not so clear to me, but there MUST BE A GOOD REASON.
This is question for expert engineers and for much testing and research, which is beyond the scope of the simple diy hobby man like myself.
I only wish to know the parameters of coil construction, and what to look for on the scope while tuning and nulling.

[kt315]

BECAUSE THE COILS ARE SO BALANCED TO SUCH PARAMETERS, AND NOT TO PERFECT NULL.
---
because all around you is developing permanently. in 80s years whites HAD NOT KNOW (CAN NOT) about
MODERN coils NOTHING. then later they did XLT and XLT coil. we know it like RAINBOW coil.
but anyway it is OLD tech.
open whites patent US4293816 and you will see NOTHING about the 'phase shift'.
NOTHING. no one brief comment.
you do ALL-METALL schematic with some DISC tuning. whites worked out some new thing on current production.
in plan it did keep to release 5900 pro sl. 3900 was just some stage in experiments.
as just they got a result they rewent on 5900.

[dbanner]

By the way, a coincidence of the phases (which ocurrs at 180 degrees) is still considered a phase shift.
With a non-resonant Rx coil, there is no phase shift (at zero null), and the phases of the Tx and Rx coincide.

So balancing the coils "off resonance" creates an inherent phase shift.
It is plain to see we are talking about the 6B and bluemax coils.

THE 6B COIL FOR THE 3900 WAS ALSO USED ON FULL DISCRIM. UNITS such as the 5900 and 6000DI. So your point is moot.