Bandido II New Schematic

[driscoll]

Major improvement is Power Supply

Regards

[Max]

Major improvement is Power Supply

Regards

Hi driscoll,
nice work...this way we get tru -5V...although not required for correct operations with right components (need just -3v or something more).
Anyway, nice work ! This way also other features could be implemented (cause we have some extra current).

Just few questions ...what's your detection range with 1 eur coin in all metal and disc mode ???
Do you use any original coil or homemade coil/coils ?
Have you encountered problems in disc section with that components e.g. on iron rejection ???

Best regards,
Max

[Max]

Hi driscoll,
nice work...this way we get tru -5V...although not required for correct operations with right components (need just -3v or something more).
Anyway, nice work ! This way also other features could be implemented (cause we have some extra current).

Just few questions ...what's your detection range with 1 eur coin in all metal and disc mode ???
Do you use any original coil or homemade coil/coils ?
Have you encountered problems in disc section with that components e.g. on iron rejection ???

Best regards,
Max

Another question...
why WIMA MKS ??? temperature coefficient instability ???
I haven't wima mks but normal poly caps and they seems ok...I have drift only when in all-metal manual...and not much high.

Best regards,
Max

[driscoll]

Hi MAX,

WIMA capacitors
metallized polypropylen capacitors - MKP
-55 to 100°C
High frequency and temp stability in pulse mode.
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Just few questions ...what's your detection range with 1 eur coin in all metal and disc mode ???
Do you use any original coil or homemade coil/coils ?
Have you encountered problems in disc section with that components e.g. on iron rejection ???
---------------------------------------------------------------
1 Euro coin 26 cm in ground in disc mode and 28 cm in all metal mode.

Iron rejection => excellent for very little objects BUT very bad for big objects.

Best regards

[driscoll]

About coil.

I use an original coil (i have an original Bandido II uMax).


Question:
- What PCB have you used Max (Quink PCB, Telus PCB or another) ?
- Have you used some decoupling capacitors on each IC (between +5/GND and -5/GND) ?

[Max]

About coil.

I use an original coil (i have an original Bandido II uMax).


Question:
- What PCB have you used Max (Quink PCB, Telus PCB or another) ?
- Have you used some decoupling capacitors on each IC (between +5/GND and -5/GND) ?

Hi discroll,
I've used Gary's 1st design...a big pcb board that is really easy to mount and gives me much freedom to put probes etc for testing cause it's larger.
It worked OK and I've just a problem regarding noise propagation at first and second channel gates, but then shielded everything and this PCB works very nice now. I've made a metallic container for my homemade to avoid noise coupling from power lines etc.

No decoupling at every IC on my homemade. Just original schematic. If you have self-oscillations you need some I think ...but consider also noise that could make it oscillate at IC8 outputs. Test with the scope for 50Hz oscillations and BF in general...if you see there you need shielding the PCB, adding ground plane or a metallic case connected to GND point.

I have goodrat's values for caps, present in Gary's revised schematic( and also in your schematic).

I have an homemade DD 22cm can detect 1eur at 30cm in ground but with weaker sound, an 20eur-cent at 22cm loud, a 1eur-cent at 20cm loud in disc mode. In all-metal things are better but in manual mode I get drift, that is normal cause to dc coupling.

I've tested that in all-metal I can ear 1eur in air test at 32cm and also more...and seems that in ground is the same but need special care on geb (gnd nulling).

Have iron rejection lacks when masses e.g. hammer is near 2-3cm from center of coil...but sometimes also with iron nails at 1cm or so.

Best regards,
Max