Bandido II coils and other stuff

[chemelec]

Hi Gary,
thank you for the info. Now I know that I can't expect much voltage there and just try to put two schottky diodes (e.g. bat73 or bat4 to get a small improvement, say to -3volts or little more if I can.
I was thinking I made a mistake on diode verse or capacitors...now I think too that this voltage converter uses too low frequency (only 5KHz) to give some -5volt on V- rail.

Best regards,
Max

I was thinking of using an MC7660 to make a Much Improved Negative supply.
But I never got around to doing a circuit board for it.

[Max]

When I built this a few years ago, I also had a Low Voltage on the Minus rail, But the detector still worked OK.
If I remember Correctly, That -2.87 is about what I had.

The Negative voltage supply Design in this detector is VERY Poor and definately low efficiency.

Hi Gary,
thank you for the info. Now I know that I can't expect much voltage there and just try to put two schottky diodes (e.g. bat73 or bat4 to get a small improvement, say to -3volts or little more if I can.
I was thinking I made a mistake on diode verse or capacitors...now I think too that this voltage converter uses too low frequency (only 5KHz) to give some -5volt on V- rail.

Best regards,
Max

[chemelec]

Hi all,
I'm building the Bandido II and now I've got the right frequency for tx = 10.002Khz
(with 30 AWG , 103 turns on 20cm inner diameter coil) but

I've this problem now:

- at V- rail terminal only -2.87 V

Is that -2.87 Volts correct for V- ??? Seems low for correct operations !
I expect this V- to be near -5.0 volt to have a good op. amp. polarization.
What's that voltage in real bandido circuit ???

My data are:
I've right pulses on R5 and R6 (square 5KHz signal , from main freq. div by 2, IC1 pin 12).
V+ is 5.02 volts, as expected.
All transistors are 2N3904 and 2N3906, according to the schematic and right positioned.
All diodes are 1N4148 and capacitor are normal electrolitics type as in schematic.
My hypothesis is that I have poor efficiency in voltage converter running at 5KHz.

Any idea ??? Any suggestion welcome.

Best regards,
Max

When I built this a few years ago, I also had a Low Voltage on the Minus rail, But the detector still worked OK.
If I remember Correctly, That -2.87 is about what I had.

The Negative voltage supply Design in this detector is VERY Poor and definately low efficiency.

[Max]

Guys...I have another problem !

Hi all,
I'm building the Bandido II and now I've got the right frequency for tx = 10.002Khz
(with 30 AWG , 103 turns on 20cm inner diameter coil) but

I've this problem now:

- at V- rail terminal only -2.87 V

Is that -2.87 Volts correct for V- ??? Seems low for correct operations !
I expect this V- to be near -5.0 volt to have a good op. amp. polarization.
What's that voltage in real bandido circuit ???

My data are:
I've right pulses on R5 and R6 (square 5KHz signal , from main freq. div by 2, IC1 pin 12).
V+ is 5.02 volts, as expected.
All transistors are 2N3904 and 2N3906, according to the schematic and right positioned.
All diodes are 1N4148 and capacitor are normal electrolitics type as in schematic.
My hypothesis is that I have poor efficiency in voltage converter running at 5KHz.

Any idea ??? Any suggestion welcome.

Best regards,
Max

[Max]

Hi,
many thanks for the useful informations.

What about wire gauge ? 30 AWG seems ok to obtain 22 ohm of resistance (KT315 data for tesoro concentric) on 62.832 meters (100 turns) : is that correct ?

I have to wrap the TX and RX in opposite direction like in the drawings, right ?

Best regards,
Max

[Qiaozhi]

Coils

The coil connection details are incorrect. In fact, the last diagram is one that I created while trying to debug a faulty Tesoro Laser.

Here's the correct wiring:

[Esteban]

Coils

[Max]

Hi all,
I've posted this on bandido forum section, but no response yet.
Don't know about wire gauge and shielding.

Maybe someone can give
me informations on already made homebrew coils.

Questions are:
1. What's the best wire gauge to build concentric for Bandido II ?
2. What's the best shield to use ? Foil or anything else ?
3. What are the frequencies that I've to see on the scope ?
4. What are phase shift to search for and at which points ?
5. Have one experiment with something different ic instead of TLC2262 ? results ?


My calculations show that AWG 30 is the right choice...anyone can confirm ?

Best regards,
Max