Bandido II coils and other stuff

[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]

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 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]

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'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 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,
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]

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,
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

The Bigger Former is the top edge of a 4 liter Ice Cream Pail. The Smaller form is one I made out of ABS Plastic on my Metal Laithe. This Coil was ONLY Made for Bench Testing Purposes. Not for outside use.

Most Wire gauges are actually pretty accurate.
But there are Definate Variations in the Insulation Thickness, Especially from one manfacturer to the other. That insulation will make more of a difference than the actual small variations in the wire size.

Besides this Normal variation in Insulation Thickness, you can also get Double and Tripple Coated wire.

I stock 8 pound spools of about 15 different gauges, just for my expermenting. (between 16 to 40 AWG)
(My cost is $35.00 Canadian a Roll, A Really GOOD Price.)
I even have some Square and Rectangle Gauges.

I Specifically Designed this Split board as a Request from someone Back in 2004.
I don't really have any need for this detector. My only purpose was to make a Working PCB. So for my testing, I just use Whatever Capacitors I have on hand.
(This Board will Never actually be used in the field)

Yes, Silver Mica, NPO and some other fancy types will Definately be Better in some places on the board.

These Two boards PLUG Together with Single Inline Pins.
** For more convenient Testing and the need to Replace Parts, A set of Ribbon cables with these "Sip Pin Plugs" (male and Female Ends), can be easly made so the boards can be operated Side by Side.

Take care.....Gary

[Max]

The Bigger Former is the top edge of a 4 liter Ice Cream Pail. The Smaller form is one I made out of ABS Plastic on my Metal Laithe. This Coil was ONLY Made for Bench Testing Purposes. Not for outside use.

Most Wire gauges are actually pretty accurate.
But there are Definate Variations in the Insulation Thickness, Especially from one manfacturer to the other. That insulation will make more of a difference than the actual small variations in the wire size.

Besides this Normal variation in Insulation Thickness, you can also get Double and Tripple Coated wire.

I stock 8 pound spools of about 15 different gauges, just for my expermenting. (between 16 to 40 AWG)
(My cost is $35.00 Canadian a Roll, A Really GOOD Price.)
I even have some Square and Rectangle Gauges.

I Specifically Designed this Split board as a Request from someone Back in 2004.
I don't really have any need for this detector. My only purpose was to make a Working PCB. So for my testing, I just use Whatever Capacitors I have on hand.
(This Board will Never actually be used in the field)

Yes, Silver Mica, NPO and some other fancy types will Definately be Better in some places on the board.

These Two boards PLUG Together with Single Inline Pins.
** For more convenient Testing and the need to Replace Parts, A set of Ribbon cables with these "Sip Pin Plugs" (male and Female Ends), can be easly made so the boards can be operated Side by Side.

Take care.....Gary

Hi Gary,
thanks for the infos. I'm quite far away from Canada so I have to add international transport expenses and taxes if I need to buy something outside my country.

In particular I'm interested in teflon insulated wire. I have some but need more. Have to buy.

Actually I need some wire at the moment...I have a dealer that sells to me also small lenght (but not under 100 meters). But at the moment I can't go there to buy (at about 80Km from my town) because I'm very busy and no time to travel ! There are many dealer here of this stuff for transformers/motors etc but most don't sell small quantities but entire kilometrics rolls so I've to travel a bit to get about quantity I need.

"** For more convenient Testing and the need to Replace Parts, A set of Ribbon cables with these "Sip Pin Plugs" (male and Female Ends), can be easly made so the boards can be operated Side by Side."

Good idea ! I'll do this way with next board.

Yes, I use also NPO quite often where needed.

I'm wounding the "rx bucking coil" on top of TX coil now...leaving it free for further adjustments, everything is AWG30. I'm using nails and plywood as temp support.

Best regards,
Max

[chemelec]

Hi Gary,
thanks for the infos. I'm quite far away from Canada so I have to add international transport expenses and taxes if I need to buy something outside my country.

In particular I'm interested in teflon insulated wire. I have some but need more. Have to buy.

Actually I need some wire at the moment...I have a dealer that sells to me also small lenght (but not under 100 meters). But at the moment I can't go there to buy (at about 80Km from my town) because I'm very busy and no time to travel ! There are many dealer here of this stuff for transformers/motors etc but most don't sell small quantities but entire kilometrics rolls so I've to travel a bit to get about quantity I need.

Best regards,
Max

My Wire Supplier is also Quite far away from me, but about 3 times a year I drive 4 hour, Each way to get more from him in Vancouver.
I Usually make it a 3 day trip and buy other stuff as well. But He doesn't have much Teflon wire and I don't really use it much either.

I use Litz wire sometimes, but I usually make my own.

I really doubt that Teflon wire would make that big of a difference on this coil. And to get the Required Inductance, your going to need a Lot More Turns.

By the way, an 8 Pound spool of 30AWG Enamel wire is about 25,000 Feet. One roll Keeps me going for a little while.

Take care.....Gary

[Max]

My Wire Supplier is also Quite far away from me, but about 3 times a year I drive 4 hour, Each way to get more from him in Vancouver.
I Usually make it a 3 day trip and buy other stuff as well. But He doesn't have much Teflon wire and I don't really use it much either.

I use Litz wire sometimes, but I usually make my own.

I really doubt that Teflon wire would make that big of a difference on this coil. And to get the Required Inductance, your going to need a Lot More Turns.

By the way, an 8 Pound spool of 30AWG Enamel wire is about 25,000 Feet. One roll Keeps me going for a little while.

Take care.....Gary

Hi Gary,
wow 25,000 feet at very good price ! I'd like to buy a roll...but unfortunately for me
I think it's not so cheap to move 8pound of stuff around the globe...don't know how much
can it costs by DHL,FEDEX or something else.

"I really doubt that Teflon wire would make that big of a difference on this coil.
And to get the Required Inductance, your going to need a Lot More Turns."

I've read the bbsailor article on fast monocoils for PI. So I've tested some teflon insulated
0.37mm diameter wire (a special wire for "hot" devices) and worked very well.
I've breaked the 8uS barrier that is very very good for me!
Yes, it's thicker than enamelled and not suitable for VLF kind of coils. But for PI is ok.

I have kilometers of old litz... very good quality but too thin for most applications.
It was used in crystal circuits...and radio in general...
I think it could stay in a museum ! (seems it was made in 40's, don't know for sure!)

Today it's not so used as in the past. Not so thin at least.

Best regards,
Max

[chemelec]

Hi Gary,
wow 25,000 feet at very good price ! I'd like to buy a roll...but unfortunately for me
I think it's not so cheap to move 8pound of stuff around the globe...don't know how much
can it costs by DHL,FEDEX or something else.

"I really doubt that Teflon wire would make that big of a difference on this coil.
And to get the Required Inductance, your going to need a Lot More Turns."

I've read the bbsailor article on fast monocoils for PI. So I've tested some teflon insulated
0.37mm diameter wire (a special wire for "hot" devices) and worked very well.
I've breaked the 8uS barrier that is very very good for me!
Yes, it's thicker than enamelled and not suitable for VLF kind of coils. But for PI is ok.

I have kilometers of old litz... very good quality but too thin for most applications.
It was used in crystal circuits...and radio in general...
I think it could stay in a museum ! (seems it was made in 40's, don't know for sure!)

Today it's not so used as in the past. Not so thin at least.

Best regards,
Max

As to getting Wire, Besides MARS, Where do you Really Live?
Email Me.
Definately Notv Practical for a8 Pound Spool, But maybe I could do something for you.

Yes, Teflon is good for PI Coils.

**Bbsailor sent me some samples to do some coils for Comparative Testing to my coils. (VERY NICE OF HIM)
They did work slightly better, but at the Price of the Teflon wire, I don't think the Results were worth it. At least Not for My applications

Take care...Gary

[Max]

As to getting Wire, Besides MARS, Where do you Really Live?
Email Me.
Definately Notv Practical for a8 Pound Spool, But maybe I could do something for you.

Yes, Teflon is good for PI Coils.

**Bbsailor sent me some samples to do some coils for Comparative Testing to my coils. (VERY NICE OF HIM)
They did work slightly better, but at the Price of the Teflon wire, I don't think the Results were worth it. At least Not for My applications

Take care...Gary

Hi Gary,
Done. I found teflon is very good for PI...I've realized different ones (stuart, gs4...etc some by protoboards and others with true PCB; I have 2 stuart now...with small differences...and close performances too). A good GS4 proto also that works good but:
my real problem with PI are ceramic fragments...so I've realized I need a good disc unit...easy to use, and Reg suggest "Bandido"!
So, now I'm dealing with bandido to avoid ceramic interference, in some search fields, that are very boring and also too-digging-addicted.
I use PI when I do beach searching, but not really interested in beach searching.

I've used VLF's before but sometimes they were too low sensitive. Hoping that Bandido isn't like these old I've used in past years. Anyone talk good things about tesoro and bandido expecially but I never had one...can't say before field tests - also some older vlf sounded loud with ceramics !.

Best regards,
Max

[chemelec]

Just an Update on my progress:

As I Said, It was working good, but one board had a few small errors that I temporary just fixed.

I have now Revised these "Split Bandido PCB's", to properly correct them.
I Also Re-Made the one board that had the small Errors and have re-assembled and re-tested it.

I Will Post the PCB's later today, along with Pictures of the two Assembled PCB's.

I still have some work to do to revise the schematic.
Hopefully I will get that completed this coming week.

This unit uses the MC7660 for the Negative Supply and it delivers a "Negative 4.5 volts". The Positive is still Plus 5 volts.

The board also Incorporates a 2 LED Battery Indicator.
(Good or Low battery Indication)
I think its useful, but you can Either Add these components or Leave them off.

Take care....Gary