Bandido II uMax, & commercial schematics

[Carl]

https://www.geotech1.com/thunting/te...ndido2umax.pdf


Here is the B2uMax schematic. I also own a Bandido uMax, but it uses a ceramic thick-film substrate for the main circuit, and has laser-trimmed thick-film resistors. Therefore, it is almost impossible to trace out.

I mentioned a while back creating a page for commercial schematics. I wrote several detector manufacturers for permission to post old schematics, and the initial responses were pretty much the same: "sounds ok, let me check on it." Then, nothing.

So, I will go ahead with it, and if anyone complains, make adjustments as needed. If you have any schematics you want me to post, let me know. I do require that they be reverse-drawn off a circuit board, and not a copyrighted manufacturer's schematic.

- Carl

[C.Pruysers]

Re: Bandido II uMax, & commercial schematics

Carl . There must be something wrong . I cannot open the info . Something wrong with the code used . Kees

[Chris]

Re: Bandido II uMax, & commercial schematics

Hi Kess

there is nothing wrong with the code. You must upgrade your Adobe Reader to version 5.x. Version 4.x doesn't work anymore.

Chris

[Russ_NY]

Re: Bandido II uMax, & commercial schematics

It worked just fine here with 4.0, though I probably should upgrade.

[Marcello]

Re: Bandido II uMax, & commercial schematics

Hi Carl, thanks of the circuit of the bandido II.
Do you think both better of the eldorado that I have realized?
In affirmative case you would be so kind if I sent me a photo of the side component of the PCB?
Thanks!

[C.Pruysers]

Re: Bandido II uMax, & commercial schematics

Massimo helped me on the print of the schematic. Thank you Massimo , and thank you Carl for sharing with us . Kees

[Randy]

Bandido II uMax, Modification Question

Does anyone have any ideas on how to modify this circuit so that the detector would be able to operate in highly mineralized conditions like the wet salt sand at the beach?

Randy

[Goodrat]

Re: Bandido II uMax, Modification Question

I'd like to know also. I'm experimenting with lowering the op freq to accomplish this. The ground balace seems to want to go full CW if the freq is down to about 9.5Khz (balancing in air to a piece of ferrite). I don't know if that is low enough.

[Goodrat]

Hello Carl. Comments.

I've been playing with my Cutlass II and added IC6 to make the BAndido. A couple of points. You can lower R1 to 1K to get a hotter signal. Not sure of the consequences.
Also when I turn the Disc pot full CCW (left on schem) the pulses at IC5b output double pulse, as is an oscillation. This does not show up the audio but drastically affects the depth. Changing to the 9x8 coil fixes it, but I think I will add an 8 or 10K resistor in series with the pot.
Also, will someone look and see if their Bandido has a jumper between P24 and P25? I'm sure there is, but just verifying. This is the mode switch for the Cutlass for silent all metal.

[Goodrat]

Wet salt...

After reading this forum, there was some discussion about extending the gound balance of the Silver sabre (adding a cap and resistor to the GB pot), but no one had any tested conclusions. My machine is a Cutlass II which is identical to the recently posted Bandito II uMax schematic.
I'm trying to test with some wet table salt in a jar, but I'm not sure if I'm getting anywhere.
I have a 47K in series with the 50K GB pot and between the two is a .001uF to ground. Also trying a .0022uF. The goal here is to add a wet salt switch for SE florida beaches.
I don't see any change at least with the jar. The threshhold tone still increases.

[Marcello]

What performances?

What performances does it have for a 50 centeuro in air?
I have built the old eldorado that works to 8V and therefore a VppTX of 12V;
doesn't being the BandidoII to 5V have inferior performances?
Is it worthwhile to realize it?
Thanks!

[Goodrat]

Re: Wet salt...I think I got it!

With a 50K pot and comparing the xmit signal say at C12 to the GB shifted signal at IC5A output, the range is about 100 deg (CW) to 154 deg (CCW or 100K). Now wet sand wants to be more negative but not much is gained with adding more resistance. What I did was to add another pole by using the 10K already at the input of IC5A (-) and tacked a 1000pF right at the op amp input to ground.

With this cap I get a range of 137 deg (CW) to 180 deg (CCW). Using a switch I now have almost a continuous range of 100 deg (CW) to 180 deg (CCW).

I hope this is enough for wet sand. It would be nice to continue using the 50K 3 3/4 turn pot.
Adding more capacitance does not give much more than 180 deg. I will play with increasing C12, but I like this for easy switching.
Comments? Will 180 deg be enough?

[Marcello]

Re: Bandido II uMax, & commercial schematics

Excuse me, but C5 is contrary?

[Goodrat]

But what is really required?

Is is low conductivity of the salt, capacitance effect, signal loading. What is really required with dealing with wet salt? Maybe getting more negative with the ground balance is the wrong approach.
What makes one machine less affected than another?

[Marcello]

some errors

There are perhaps some errors:
- C29 10n?
- C7 ELETTROLITICO?
- C42 AND C45? ARE THEY INVERTED?