Bandido II uMax - strange iron-copper disc

[Max]

1) What are "Goodrats Cap Values"?

2) Can "Goodrat" Confirm that these Scope Traces were taken from an Actual "Manufactured Bandido".

I Think this info Would be appreciated by all.

Thanks in Advance...Gary

Hi Gary,

1. the values you posted in your revised schematics (also found in french revised schematic and there indicated as yours) : the ones goodrat mailed to you after measuring caps out of the circuit
2. I don't know for sure but think so cause I get better response and disc with these values and diagrams than with original cap values from Carl's schematic

Example: with first set (Carl's) I get problems with iron disc...completely out of phase ...with second set (goodrat's) I get a near-to-complete iron disc for every position of disc pot. Sound just when an iron mass is really near center of coil...means that some strong perturbation of field lines can affect disc capability. Sounds with brick but less than with first set.

A little problem is now around geb ...where I can't get zero as indicated by Qiaozhi but I have same diagram of Goodrat and I can null nearing ferrite sticks...that's indicates geb seems working now. With first set I can't completely tune out ferrite sticks at different distancies.

Of curse is not the "smocking gun" evidence that everything is right (like in original-bought bandidos) in my homemade ...but I think now it's nearer to a bought one.

So I think you are right when say that you think these (goodrat's) are correct values.

Best regards,
Max

[porkluvr]

Goodrat's O'graph

Sorry folks, this is long:
I, porkluver, apologize for irresolutely stating that Goodrat’s oscillograph photo that I borrowed was made with a Bandito. It wasn’t. I found it in the Super Sabre /Bandito –Tesoro- project section of this website and it was a Cutlass II he was showing. I posted the link to the thread for anybody to read and then I went to bed. The sun was ready to come up. I read it later and then I realized my gaffe, but, then, it was too late.

On the subject of Bandito discrimination circuit component values:
Darth Carl's original drawing (Bandito II uMax) shows C10=130pF. Gary, your update shows C10=22pF, and as I’m sure you know there is a wide variance in the DISC function depending on which value is choosen. So, who’s right? Gary’s and Carl’s are the only two Bandito schematics I’ve come across. Max, what capacitor value do you have for C10 in the DISC?

Disclaimer: I live in a suitcase and only wish I had an ocilloscope and a soldering iron (don't snort). But I do have a virtual lab running an Athlon XP, with LTspice a.k.a. SwitcherCad (please don’t snort again).

But seriously, Using C10=22pF makes my simulation results correlate fairly well with Goodrat's photo. But remember: HE WAS PROBING A CUTLASS II. What are the differences? Hmmm. My simulation results with a Bandito circuit correlate pretty well with Goodrat’s o’graph when I use 22pF. I’ll double check that and post my results if anybody's interested.

Please correct me if I’m wrong but none of the other denizens of the Tesoro page have given a picture of what happens in a Tesoro phase reference circuit. I am interested in a building a Bandito. Although Goodrat’s photo is good, I have been basing and reinforcing preconcieved notions on his data - all the while not even knowing how closely it can represent a Bandito. Later.

[Qiaozhi]

Yes, iron is rejected at minimum disc too. But with big masses happens sometimes it sound briefly.

I do not possess a BandidoII, only an original Bandido, which may be different. Not had time to back-engineer just yet. As far as I'm aware, it is quite normal for the signal to break through when a large ferrous object is brought close to the coil. A large nail will probably get rejected ok, but a horse shoe for example will give a signal with any detector.

[Qiaozhi]

Sorry folks, this is long:
I, porkluver, apologize for irresolutely stating that Goodrat’s oscillograph photo that I borrowed was made with a Bandito. It wasn’t. I found it in the Super Sabre /Bandito –Tesoro- project section of this website and it was a Cutlass II he was showing. I posted the link to the thread for anybody to read and then I went to bed. The sun was ready to come up. I read it later and then I realized my gaffe, but, then, it was too late.

On the subject of Bandito discrimination circuit component values:
Darth Carl's original drawing (Bandito II uMax) shows C10=130pF. Gary, your update shows C10=22pF, and as I’m sure you know there is a wide variance in the DISC function depending on which value is choosen. So, who’s right? Gary’s and Carl’s are the only two Bandito schematics I’ve come across. Max, what capacitor value do you have for C10 in the DISC?

Disclaimer: I live in a suitcase and only wish I had an ocilloscope and a soldering iron (don't snort). But I do have a virtual lab running an Athlon XP, with LTspice a.k.a. SwitcherCad (please don’t snort again).

But seriously, Using C10=22pF makes my simulation results correlate fairly well with Goodrat's photo. But remember: HE WAS PROBING A CUTLASS II. What are the differences? Hmmm. My simulation results with a Bandito circuit correlate pretty well with Goodrat’s o’graph when I use 22pF. I’ll double check that and post my results if anybody's interested.

Please correct me if I’m wrong but none of the other denizens of the Tesoro page have given a picture of what happens in a Tesoro phase reference circuit. I am interested in a building a Bandito. Although Goodrat’s photo is good, I have been basing and reinforcing preconcieved notions on his data - all the while not even knowing how closely it can represent a Bandito. Later.

The component values may not be the same between Tesoro detectors, because of the TX frequency and other design differences, but I think the waveforms will be almost identical.

[Geo]

Hi Max.
Can you tell me if the bandido has the same sensitivity at disk mode and at all metal mode ???
At who distance can detect one or two Euro coin at Disk mode and at all metal.

[marcellotronic]

I Have build the bandido II from the schematic posted by Carl and in disc
it finds 50 cent to 25cm, in all-metal it finds 50 cent to 18cm

[Max]

Hi Max.
Can you tell me if the bandido has the same sensitivity at disk mode and at all metal mode ???
At who distance can detect one or two Euro coin at Disk mode and at all metal.

Hi Geo and all,
I noticed that in disc mode bandido II lose performaces. Till now, with goodrat's set of cap I get -20% sensitivity when in disc mode respect to all-metal-manual setting. If you refer to all-metal auto (feedback in) you get similar performances just a bit lower say -5%.
I get 2 eur coin at about 24-25 cm in disc mode where can get at 30 and more in all-metal manual. When in all-metal auto I get at 26-27 cm but not at 30.
Noticed that with Carl's values I get better in all-metal modes...due maybe to geb not working well.

What to say...nothing special about performance...but disc works well I think with goodrat's caps. I reject most of the iron...but still get signals from big masses close to the coil...and also from bricks...can't distinguish a piece of brick from a coin...where brick is at 3-4 cm from center of the coil ! This could be a problem in search field where there are many pieces of pottery-bricks-ceramics (I think you know what I mean).

Instead of marcellotronic...I get less depth when in disc mode. Diagrams are really close to goodrat's cutlass II.

Anybody has the schematic of cutlass II to post...cause I'd like to take a look at disc and geb design to figure out if it's the same of bandido II (I suppose so).

To Qiaozhi: thanks again, yes with nails is not a problem. I get complete reject on iron under about 50gr of mass with lillte surface...problem shows when large plates or bigger masses involved e.g. an hammer or an iron sheet
(e.g. 10cmx5cm) moving near the coil. Sound is sometimes abrupt...due to imbalance of disc end section.

Best regards,
Max

[Max]

Sorry folks, this is long:
I, porkluver, apologize for irresolutely stating that Goodrat’s oscillograph photo that I borrowed was made with a Bandito. It wasn’t. I found it in the Super Sabre /Bandito –Tesoro- project section of this website and it was a Cutlass II he was showing. I posted the link to the thread for anybody to read and then I went to bed. The sun was ready to come up. I read it later and then I realized my gaffe, but, then, it was too late.

On the subject of Bandito discrimination circuit component values:
Darth Carl's original drawing (Bandito II uMax) shows C10=130pF. Gary, your update shows C10=22pF, and as I’m sure you know there is a wide variance in the DISC function depending on which value is choosen. So, who’s right? Gary’s and Carl’s are the only two Bandito schematics I’ve come across. Max, what capacitor value do you have for C10 in the DISC?

Disclaimer: I live in a suitcase and only wish I had an ocilloscope and a soldering iron (don't snort). But I do have a virtual lab running an Athlon XP, with LTspice a.k.a. SwitcherCad (please don’t snort again).

But seriously, Using C10=22pF makes my simulation results correlate fairly well with Goodrat's photo. But remember: HE WAS PROBING A CUTLASS II. What are the differences? Hmmm. My simulation results with a Bandito circuit correlate pretty well with Goodrat’s o’graph when I use 22pF. I’ll double check that and post my results if anybody's interested.

Please correct me if I’m wrong but none of the other denizens of the Tesoro page have given a picture of what happens in a Tesoro phase reference circuit. I am interested in a building a Bandito. Although Goodrat’s photo is good, I have been basing and reinforcing preconcieved notions on his data - all the while not even knowing how closely it can represent a Bandito. Later.

Hi porkluvr,
no problems. Thanks again for your help. I think they (cutlass and bandido) share similar circuits parts (e.g. geb and disc). I get almost the same diagrams with goodrat's values...and can't be a case.

I also noticed that golden-bandido has the same structure...but in schematics I can see again old cap values like in original bandidoII Carl's schematic. Maybe depends on the fact that Carl used the same instruments to misure both (badido's and cutlass's caps)...in circuit...having bad readings on their actual values.
Reverse eng is not an easy task on assembled circuits...and expecially when in smt !

I think that goodrat maked a good work measuring them out of circuit.

Best regards,
Max

[Geo]

Thanks. As Max said "nothing special about performance". And who has special performance ???? All are "about the same ". There are very litle models that have 20....30% better performance.
Regards

[chemelec]

Goodrat or Anyone here.
Do you Have the Schematic of the "Silver Saber".

Either to Post it here or Send it to me in an Email.
[email protected]

I would like to do some Comparisons between it and the Bandido.

Gary

[Geo]

Hi Gary . I attach you the pdf file for Silver Sabre.

[Max]

Goodrat or Anyone here.
Do you Have the Schematic of the "Silver Saber".

Either to Post it here or Send it to me in an Email.
[email protected]

I would like to do some Comparisons between it and the Bandido.

Gary

Hi Gary,
I see some differences.
1. voltage converter uses 7660
2. two channel for geb and disc (where bandido has 3 analog ports)
3. negative feedback on middle stages (to stabilize I think)
4. uses older components (LFs)
5. geb and disc uses different caps values than cutlass/bandido/golden-ban
6. similar are: positive regulator, output section, sum-network (and sens), oscillator

But maybe it is better than bandido II...can't say.

What do you think about ?

Could be interesting study the geb and disc waveforms/shifts.

Best regards,
Max

[chemelec]

Hi Gary . I attach you the pdf file for Silver Sabre.

THANKS GEO.

Another STRANGE THING.
According to that Scope Trace, Posted here somewhere,

Showng Points P23, P24 and P28.
On P28, I CAN'T Get that Sinewave on the scope.

My Board is Definately Correct to the Schematic and appears to be Working OK.
(The Only part of this circuit that doesn't seem to make much Difference is the Sensitivity Control, But that Not related to this problem.)

IF I Remove IC7, Yes I get the Sinewave.
But with IC7 installed, I get a Greatly Reduced Signal Trace that in NO-WAY appears as a SineWave.
(Can't Describe it, But maybe I'll post a Picture of it.)

Increasing the Capacitance of C9 to 1000pf and I do get a Good Sinewave but than the Descrimination Does not work Properly to Actually Descriminate.

Has Anyone Else Done these SCOPE TESTS?

ANY COMMENTS WELCOME!

[Max]

THANKS GEO.

Another STRANGE THING.
According to that Scope Trace, Posted here somewhere,

Showng Points P23, P24 and P28.
On P28, I CAN'T Get that Sinewave on the scope.

My Board is Definately Correct to the Schematic and appears to be Working OK.
(The Only part of this circuit that doesn't seem to make much Difference is the Sensitivity Control, But that Not related to this problem.)

IF I Remove IC7, Yes I get the Sinewave.
But with IC7 installed, I get a Greatly Reduced Signal Trace that in NO-WAY appears as a SineWave.
(Can't Describe it, But maybe I'll post a Picture of it.)

Increasing the Capacitance of C9 to 1000pf and I do get a Good Sinewave but than the Descrimination Does not work Properly to Actually Descriminate.

Has Anyone Else Done these SCOPE TESTS?

ANY COMMENTS WELCOME!

Hi Gary,
I've done all tests and they were ok.
When Goodrat say P28 is -input of ic7B (he have done in a past thread...follow the link where the pic is) there is a problem: at that input I get a sine but really small signal not 7.68V pk-pk like in the picture--> so I concluded he means signal at collector of T1, that is main tx frequency from osc. I've used this point as P28.

Also P23 can't be at C18...you will get a charge-discharge waveform and not a square pulse---> I've concluded he means pin1 of IC5a for P23 (cause also P24 is output of IC5b, directly the output of comparator).
P23 goes to analog port of disc channel 2 ; P24 goes at analog port of disc channel 1: that makes sense cause both are gating signals for the two channel.

This way all fits like in posted picture. Really close !

I think that mistakes were related to assembly of board and then not easy accessible test points marked on. But, to be sure we need Goodrat to ask or someone else that has the same original board!
For now only my ideas...of what's happened.

Best regards,
Max

[chemelec]

Thanks Max, That was Also what I Thought and how I also finally did the testing on my unit.
I was hoping someone else to come to the same conclusions.

Take care...Gary
*****************************************

Hi Gary,
I've done all tests and they were ok.
When Goodrat say P28 is -input of ic7B (he have done in a past thread...follow the link where the pic is) there is a problem: at that input I get a sine but really small signal not 7.68V pk-pk like in the picture--> so I concluded he means signal at collector of T1, that is main tx frequency from osc. I've used this point as P28.

Also P23 can't be at C18...you will get a charge-discharge waveform and not a square pulse---> I've concluded he means pin1 of IC5a for P23 (cause also P24 is output of IC5b, directly the output of comparator).
P23 goes to analog port of disc channel 2 ; P24 goes at analog port of disc channel 1: that makes sense cause both are gating signals for the two channel.

This way all fits like in posted picture. Really close !

I think that mistakes were related to assembly of board and then not easy accessible test points marked on. But, to be sure we need Goodrat to ask or someone else that has the same original board!
For now only my ideas...of what's happened.

Best regards,
Max