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if you are useing a 5 pin domino (SL175FX) coil connecter is this so you can use an original tesoro coil
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Yes. I want to use it with original Tesoro coil as I have several. I have (2) 8" white open centers, (2) 8" white solid types, (1) brown 8" open center, (1) 10" open center. I'd like to try making my own coil later. Even then, I'd like to use the same connector so I can switch back and forth between stock and homemade easily.
MercComment
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could you tell me if this is right four wiring up a coil.coil side connector first then coil connector pcb
pin 1 Violet
pin 2 nc
pin 3 Orange
pin 4 Grey
pin 5 GND (shield, no colour)
Following R26 -> RX is Pin3 (purple)
Following R27 --> RX ist Pin4 (gray)
Following C2 --> TX ist Pin1 (orange)
Following C1 --> TX ist Pin5 (Sheild)Comment
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See diagram below.Comment
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PCB is made. Not my best looking board but I believe it will be ok. Just got drill a lot of holes and start soldering.Comment
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Very nice, Merc, despite some shortings.Comment
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I believe the schematic I've been working from has an error. The modified negtive 5V supply does not work as shown. The PNP passing transistor does not pass any voltage when biased as shown. I believe another resistor is needed from collector to base. In the meantime, I have bypassed that transistor on my board and have good +5V and -4.77V.
MercComment
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After looking at the -5V converter, I'm wondering if the 3.9K resistor to ground should actually be going to the base of the PNP pass transisitor. Gary, if your following this thread, maybe you could check on that.
I have all components soldered except for the ones that Jameco shipped the wrong value. I ordered 5.1K, I got 510ohm. I also ordered 1.2K and got 120ohm. I double checked the part number online and it should have been the right value. I'm also missing a 180pF silver mica cap that I messed up and ordered 18pF. Oh well. With all other components in and a solder bridges cleared, I have +5V and -4.66V on all op-amps. It's getting there.
MercComment
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Looking at the pictures of the PCBs on Gary's website, it looks like the emitter of the pass transistor is turned towards pin5 of the 7660 ic.
Something must be wrong somewhere in that area. The schematic shows the collector connected to pin5.
Merc
http://www3.telus.net/chemelec/Proje...it/2-SIDES.JPGComment
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Well I have my Bandido 2 working on the table. The capacitor values that were modified in the Ground Balance and Discrimination circuit did not work for me. The detector would make noise but the discrimination was totally screwed up. The values of C9, C10, C12, C13, C14 and C18 are critical to proper discrimination because they all shift the phase of the receive signal. I replaced all caps with values from original drawing and after adjusting the ground balance control it worked in all metal and disc mode. The only problem I have now is that battery check does not seem to work properly. I'm using a bench supply for testing and if I give the detector 9V I get a nice long tone on turn-on. If I give it 6V, I still get the exact same long tone. This may be related to my negative supply being -4.66V. I'm thinking the original design probably put out much less considering it was a charge pump with 2 diodes and a pass transistor. Possibly more like -3V. I'll search through the forum to see what a "normal" value is for this supply.
MercComment
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I'm still trying to make slight changes to my Bandido2. The discrimination is working now but a nickel was getting discrminated at about where the number 6 would be on my dial. I'm use to a nickel dropping out at about4 on every Tesoro that I have so I decided to adjust the circuit somewhat. I experimented by paralleling other caps across C9 which is originally 100pF. I knew I needed to shift the phase of the TX sine wave one way or another but I wasn't sure which. By adding a 150 pf across C9, the nickel coin dropped out right about where the 4 will be if I ever get my front label printed. So, I changed out the 100pF for a 250pF I found in my junk parts and the disc seems very similar to my other Tesoros. However, my Bandido 2 will even reject a quarter at max discrmination. I'm not sure if thats normal.
Now if I can get the battery test working. Using the original values as shown in the original schematic, I get a loud tone for 3-4 seconds with 9V input to the board. I still get a somewhat lesser tone for 3-4 seconds with 6V fed to the circuit. On my other Tesoros, it seems like the tone length and loudness varied with battery voltage. Looking at the Bandido battery test circuit, there is no way for the length of the test to vary. The voltages tied to the timing components, C7 and R12, are fixed voltages. Regulated +5 at the top and the negative voltage at the bottom that is derived from the positive supply, let's say it's a fixed -3V. That's all that control the length of time that the 4066 switch is turned on connecting the test circuit to the audio output stage. The battery voltage is divided and input to one of the inputs of the op-amp which will affect the voltage output that gets switched out through the 4066, but than won't affect the length in any way.
According to the Bandido II Umax manual on Tesoro's site, As the battery ages, this sound is less intense and fades out more quickly.
Perhaps someone out there with an original Bandido II uMax could test there detector and see how it's supposed to work because something just doesn't seem right about that circuit.
MercComment
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Here is a picture of my completed PCB. I'm still not sure that my ground balance contol is proper. It can ignore a small piece of ferrite but only with the ground balance control all the way at one end(pot measures 48K). So I chaned the 180pF going into gb control with a 300pf. This makes the ferrite null point closer to the center of the pot. I'm not really sure if this correct but it seemed better to have some range to either side.
The discrimination is good but I would still like the point of discrimination of US nickels and gold rings to be at about 4 on the dial instead of 6 or 7 which is what I had to start with. I've started to wonder if maybe Tesoro uses logarithmic or audio taper pots in there units. That could explain the difference. Studying the Tesoro Silver Sabre II schematic, I see that it uses a 100K fixed resistor across the low end of the 100K disc pot. I've tried this and it does help shift the discrimination in the right direction and my unit no longer rejects a US quarter at max discrimination.
I'm still needing help with the battery check on this unit. I can't see no way for the battery test length to vary since the timing components are charging with fixed supply voltages. The intensity of the test tone varies with supply voltage on my unit, but not the length. The manual says both change with battery strength.
MercComment
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More pics of pcb in case.
MercComment
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WOW making your own detctor something i could only dream about.
i hope all the hard work you have put in to this project pays off for you and please do keep us updated on all of your progress on this machine. cant wait to see the full end results.............
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I have only tried my detector in my back yard but I was able to find a cheap child's ring and a small heart from a child's pendant. The discrimination is very good. The sensitivity is just average. It will detect a gold wedding band at about 7-8 inches. Most coins around 6-7 inches. These are air tests only. The all metal mode is working pretty well after adding 20Meg of resistance across the Auto/Normal switch. This gave some input to IC6a with the switch in the Normal position. Without the 20Meg, the input to IC6a is floating while the output is still connected to IC6b and it seemed to be adding sporadic noise to my all metal mode. Other Tesoro designs have something between 12Meg and 100Meg in that part of the circuit. 20Meg gave me a slow re-tune while pin-pointing that works for me. I wished I had used a larger box. The pots I chose were full sized approx. 1" diameter types and the front panel was really crowded. Here is a pic of the unit which uses the rod from my old Silver Sabre 2.Comment
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