Bandido II coils and other stuff

[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

[Esteban]

Coils

[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:

[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

[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

[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]

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 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]

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.

Hi Gary and all,
other problems with bandido...unfortunately

I've tested the V- rail output using only tx stage , 4024 ic and voltage converter
and transistors all mounted
obtaining (refer to gnd):

V- = -2.87 Volts

Now I've tested with full ics and almost everything mounted and obtained then:

V- = +0.65 Volts (hey! it have to be negative or not!? it was -2.87 ...)

I'm really confused now! Say stupified !

Seems that the power on V- rail is not enough to supply all ICs and then a kind of
reverse happens due to some forward conduction in op. amp. ic.
Total consumption is 26 mA only !!! But if I connect a small speaker consumption raise
to about 60mA steady with a constant screaming.
Seems that LM393 don't work as expected and also other ics have too low polarization to work as expected !

Any idea ??? any suggestion welcome.

Best regards,
Max

[chemelec]

Hi Gary and all,
other problems with bandido...unfortunately

I've tested the V- rail output using only tx stage , 4024 ic and voltage converter
and transistors all mounted
obtaining (refer to gnd):

V- = -2.87 Volts

Now I've tested with full ics and almost everything mounted and obtained then:

V- = +0.65 Volts (hey! it have to be negative or not!? it was -2.87 ...)

I'm really confused now! Say stupified !

Seems that the power on V- rail is not enough to supply all ICs and then a kind of
reverse happens due to some forward conduction in op. amp. ic.
Total consumption is 26 mA only !!! But if I connect a small speaker consumption raise
to about 60mA steady with a constant screaming.
Seems that LM393 don't work as expected and also other ics have too low polarization to work as expected !

Any idea ??? any suggestion welcome.

Best regards,
Max

You Have a Problem Somewhere.
My Origional PCB Design Worked Fine, Using te parts on my schematic.

Here is a Link to it.
THE SPLIT PCB DOES NOT WORK and I never got around to fixing it.

http://www3.telus.net/chemelec/Bandido/

[Geo]

Hi Max. If the signal of the oscilator is not hight then the output of 4024 is low (i mean no strong signal), the output of transistors at c4 is low and the same the -V. If you have scope check the signal (start from oscilator until c4). A bad coil maybe to make a problem as this.
Good luck

ps I have the same problem with Anker ss60. When i try a no good coil (low impendunce) i have not -v, -2v, +2v and the problem start at the oscilator.

[Max]

Hi Max. If the signal of the oscilator is not hight then the output of 4024 is low (i mean no strong signal), the output of transistors at c4 is low and the same the -V. If you have scope check the signal (start from oscilator until c4). A bad coil maybe to make a problem as this.
Good luck

ps I have the same problem with Anker ss60. When i try a no good coil (low impendunce) i have not -v, -2v, +2v and the problem start at the oscilator.

Hi Geo,
thank you for the infos. I'll check around the oscillator and test with other coils. Maybe also my 4024 is somehow connected to low output. I'll check again with my scope.

What's strange is that resistance expected (22ohm) and also inductance seems ok and I have 10.002 Khz at collector of T1.

Best regards,
Max

[Max]

You Have a Problem Somewhere.
My Origional PCB Design Worked Fine, Using te parts on my schematic.

Here is a Link to it.
THE SPLIT PCB DOES NOT WORK and I never got around to fixing it.

http://www3.telus.net/chemelec/Bandido/

Hi Gary,
yes your PCB is ok, I've checked before mounting components. The problem is something around voltage converter and too much current in silent mode.
I've calculated that I must have something under 18mA with original components ...but can't find MC33178 and then used MC33078 from STmicro:
but MC33178 consumes typical 1.4 mA each and MC33078 4.5 each instead.
So I have much drain here ...about 26mA that seems too current for the voltage converter to delivery at now.
Other parts are exactly as in schematic...so I think I must find mc33178 somewhere (maybe farnell) to reduce overall consumption.
I've also to check if voltage converter transistor have good driving/polarization to give the best.

Thanks again for the help.

Best regards,
Max

[Geo]

Hi Max. You have right about coil details and frequency. Check the signal at C4, it must be at least 5...6 V P-P. If not then you have problem at 4024, or back of it. ( It is a typical schematic to provide negative voltage)

[Max]

Hi Max. You have right about coil details and frequency. Check the signal at C4, it must be at least 5...6 V P-P. If not then you have problem at 4024, or back of it. ( It is a typical schematic to provide negative voltage)

Hi Geo,
I've tested on the scope.
Right, at collectors of T3, T4 (C4 +terminal) I have a perfect square signal , freq. 5KHz,
5 V-p-p and duty cycle close to 50%. That seems very good, till this point but then...
after C4, at negative terminal I had a loss indroduced by capacitor itself resulting in about
-4.4 volts, then passing through diodes and measuring at C5, negative terminal, I have about
-3.75 volts and then I have the drop on T7.
At the end, at V- rail on emitter of T7 I have only -2.87 Volts but when I haven't in circuit
any mc33078 or any other ICs but only 4024 and +5 regulator.
Because I'm sure that 33078 drains too current I can only try to find mc33178 !
But they are obsolete now and hard to find. And anyway other parts are correct but when I
connect them (tlc2262, lm393, etc) V- decrease to about -2.3 volts...
So the problem in V- is with capacitors. Too capacitor losses...at this frequency (5KHz)
and changing the diodes with schottky (already tested) doesn't improve anything here.
I've to check if another kind of capacitors with lower losses may improve things here.
I'm almost sure it is so...but think I can't drain more than 20mA, without losing in V- rail
voltage, in any case without changing all the voltage converter with something else (e.g. 7660).

Best regards,
Max