Bandido II coils and other stuff

[Max]

STUPID ME, As I said I Forgot to Balance the Coil for that Split Board Design.

Just Tested it and IT WORKS FINE.
SEE PICTURE of it.

I will see about Posting this New Split Board on my site and I will put a Link to it When I've got it Done.

Take care.....Gary

Hi Gary,
seems a very nice work. The split and the coil ! What have you used to make the formers ? seems plastic pvc but maybe I'm wrong.

Have you used plastic capacitors in other bandido circuits ? I can see only ceramic there. I've used e.g. polyester for 470nF and 100nF, thinking they are better than ceramic for that and better matched and ceramic for small values e.g. 100 pF. Are yours NPO type ? It makes some differences ?

I have to null also...now I'm wounding another tx coil because first was about AWG30 but there are small differences in wire gauge, so I have to wound new tx and rx from a new roll that is exactly 30AWG, red enamelled copper.
I'll use sope and capacitor...on RX to have good resonance point before trying to null.

Think that split board will fit easy in a smaller container, but normal is better
for testing, soldering without disconnecting tho halves etc. I like it very much now that I have to solder , experimenting, etc to find out what's wrong with my components.

Best regards,
Max

[chemelec]

Hi Gary,
maybe a shield isn't necessary because it is a real VLF, I mean 10Khz are a true low frequency to have much problems with most types of ground. But I think a shield could be necessary e.g. on wet grass and on hi-humidity terrains.
I think I'll use thin aluminium foil, because I've constructed a vlf coil before and find that foil was ok on this purpose - where not good for pulse induction. But I'm courious also about shielding plastic bags...never tested.
I know there are graphite and nickel sprays that are good for shielding but think one must use adequate protection (mask, breather, protective clotes, gloves...) to avoid trubles, so seems a bit complicated to me to do in a safe way.
I have also some copper tape - the 3m one for shielding - but just 3 or 4 meters now and some conductive mylar.

Also I have a lot of litz wire (5 and 7 conductors) really thin (0.05 mm) and enamelled. But never used for shielding.

I'll try first with foil, then the others if things go worse.

Thanks again for the help.

Best regards,
Max

STUPID ME, As I said I Forgot to Balance the Coil for that Split Board Design.

Just Tested it and IT WORKS FINE.
SEE PICTURE of it.

I will see about Posting this New Split Board on my site and I will put a Link to it When I've got it Done.

Take care.....Gary

[Max]

I Did test my Origional one out in the field, But I never added a Shield to the coil. It seemed to work quite well without it.

But a shield would probably help.

Awhile ago I Bought a Can of a Conductive Nickel spray that I plan to do some tests with in the future.(Not Cheap, Its Made by "MG Chemicals".
"Super Shield, Conductive Nickel Coating" in a 12 Ounce Can and cost $35.00 Canadian.)

Hi Gary,
maybe a shield isn't necessary because it is a real VLF, I mean 10Khz are a true low frequency to have much problems with most types of ground. But I think a shield could be necessary e.g. on wet grass and on hi-humidity terrains.
I think I'll use thin aluminium foil, because I've constructed a vlf coil before and find that foil was ok on this purpose - where not good for pulse induction. But I'm courious also about shielding plastic bags...never tested.
I know there are graphite and nickel sprays that are good for shielding but think one must use adequate protection (mask, breather, protective clotes, gloves...) to avoid trubles, so seems a bit complicated to me to do in a safe way.
I have also some copper tape - the 3m one for shielding - but just 3 or 4 meters now and some conductive mylar.

Also I have a lot of litz wire (5 and 7 conductors) really thin (0.05 mm) and enamelled. But never used for shielding.

I'll try first with foil, then the others if things go worse.

Thanks again for the help.

Best regards,
Max

[chemelec]

Hi Gary,
I've solved the problem without too much pain...

Unfortunately I can't buy original MC33178 because there aren't available at the moment
at Farnell and also Mouser seems that expect delivery of new parts for spare selling !
Digikey wants to stole my wallet... ::crazy:: 30$ of handling for 4 dip-8 ics !
So I've realized I can use temporarily MC33078 instead , untill I get some true 33178,
but by doubling the output current from voltage converter. I've done with few components
and works fine.

How to improve an inefficient voltage converter ??? Just doubling it !

Now I get V- near -4.0 volts (-3.92) with 33078 in their sockets and without changing the syncro
with main oscillator frequency, that seems ok.

Only four connections required (gnd, +5, A, B) and same components that I already have.
Just a 1 square inch of protoboard to do in about 10 minutes, without messing around with
a 555.

Only drawback is that now total silent consumption is about 28mA...too much for a 9volt
battery for long time use say > 5 hours.

I'll use six zinc-carbon dry cells or alkaline (e.g. energizer).

Think this stuff could be useful for those who haven't original components for Bandido.

But now I must realize the rx coil...uhm seems not so simple, in particular shielding.
What can I use ??? foil ? maybe some static shielding plastic like in computer cards packages???
Have you tested your unit in field search ?

Best regards,
Max

I Did test my Origional one out in the field, But I never added a Shield to the coil. It seemed to work quite well without it.

But a shield would probably help.

Awhile ago I Bought a Can of a Conductive Nickel spray that I plan to do some tests with in the future.
(Not Cheap, Its Made by "MG Chemicals".
"Super Shield, Conductive Nickel Coating" in a 12 Ounce Can and cost $35.00 Canadian.)

[Max]

I was just looking at my Previous "Split Board" PCB that I built and couldn't get to work, Years Ago.
I Did Change it to use the 7660 and That part of the circuit was Working Very Good for the Minus 5 Volt Supply.

I also Realized a Possible reason that I couldn't get it to actually Work. I Never NULLED THE COIL.
HOW STUPID!

Anyway, I have Now Nulled the coil.
So I will Re-Check it all over forany other Stupid Mistakes and see if I can get it to work.

It May take a bit of time Since its been a Few Years Since I last played with it. Got to get familiar with it again.

Unfortunately I only have a 2 of the MC33178's or I would sell you one.

I'll Let you Know how I make out.

Take care.....Gary

Hi Gary,
I've solved the problem without too much pain...

Unfortunately I can't buy original MC33178 because there aren't available at the moment
at Farnell and also Mouser seems that expect delivery of new parts for spare selling !
Digikey wants to stole my wallet... ::crazy:: 30$ of handling for 4 dip-8 ics !
So I've realized I can use temporarily MC33078 instead , untill I get some true 33178,
but by doubling the output current from voltage converter. I've done with few components
and works fine.

How to improve an inefficient voltage converter ??? Just doubling it !

Now I get V- near -4.0 volts (-3.92) with 33078 in their sockets and without changing the syncro
with main oscillator frequency, that seems ok.

Only four connections required (gnd, +5, A, B) and same components that I already have.
Just a 1 square inch of protoboard to do in about 10 minutes, without messing around with
a 555.

Only drawback is that now total silent consumption is about 28mA...too much for a 9volt
battery for long time use say > 5 hours.

I'll use six zinc-carbon dry cells or alkaline (e.g. energizer).

Think this stuff could be useful for those who haven't original components for Bandido.

But now I must realize the rx coil...uhm seems not so simple, in particular shielding.
What can I use ??? foil ? maybe some static shielding plastic like in computer cards packages???
Have you tested your unit in field search ?

Best regards,
Max

[chemelec]

Hi Gary,
I'll use tantalium to make a test. I've also modified the two caps with 1000uF but there aren't big advantages. Frequency is too low to obtain a good conversion from charge pumping process here.
I think I could use 7660 but worried about asyncronous operations instead of syncronous charge pumping of original Bandido circuit.
Also 555 running at say 80-100 Khz will be a good improvement, but noisy.

Anyway, I have to solve the too current drain before making mods on voltage converter I think. Must use original and obsolete mc33178.

I don't suggest anyone using mc33078 as replacement --> too consumption.
2 mc33078 --> about 9.8 mA of current !

Best regards,
Max

I was just looking at my Previous "Split Board" PCB that I built and couldn't get to work, Years Ago.
I Did Change it to use the 7660 and That part of the circuit was Working Very Good for the Minus 5 Volt Supply.

I also Realized a Possible reason that I couldn't get it to actually Work. I Never NULLED THE COIL.
HOW STUPID!

Anyway, I have Now Nulled the coil.
So I will Re-Check it all over forany other Stupid Mistakes and see if I can get it to work.

It May take a bit of time Since its been a Few Years Since I last played with it. Got to get familiar with it again.

Unfortunately I only have a 2 of the MC33178's or I would sell you one.

I'll Let you Know how I make out.

Take care.....Gary

[Max]

Try using some Tantalum Caps. They are Low Loss.
That is What I Used.

Maybe I should do a Re-Design of this board with a 7660?

Any one Interested in this if I did it?

Take care....Gary

Hi Gary,
I'll use tantalium to make a test. I've also modified the two caps with 1000uF but there aren't big advantages. Frequency is too low to obtain a good conversion from charge pumping process here.
I think I could use 7660 but worried about asyncronous operations instead of syncronous charge pumping of original Bandido circuit.
Also 555 running at say 80-100 Khz will be a good improvement, but noisy.

Anyway, I have to solve the too current drain before making mods on voltage converter I think. Must use original and obsolete mc33178.

I don't suggest anyone using mc33078 as replacement --> too consumption.
2 mc33078 --> about 9.8 mA of current !

Best regards,
Max

[chemelec]

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

Try using some Tantalum Caps. They are Low Loss.
That is What I Used.

Maybe I should do a Re-Design of this board with a 7660?

Any one Interested in this if I did it?

Take care....Gary

[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

[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]

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

[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

[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.

[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/

[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