FM2 on steroids

[MartyJ1963]

Hi Dom,,,Just viewed the Terminator Prospector video,,,quite impressive isn't it? I don't have anything on that particular unit in my folder but I'll have a look round to see if I can find any info on it and let you know. Cheers. Marty

[MartyJ1963]

I found these Dom,,,,Still looking,,lol. Marty

[dom44]

thanks i have the same thing, try doing an English to Russian translation for the terms "Terminator metal detector circuit" then copy and past the Russian into Google image search works with any language and any detector

also try advanced google search term


intext: ( Russian, Polish, whatever search term)

or

intitle: same as above

[MartyJ1963]

Hi Dom,,,DeJaVu?,,,,I've just been doing the same,,,on MD.RU,,,just been through a 42 page thread on Terminator Prospector,,nothing,,,a 4 page thread,,,zilch,,,just looking through another one now,,,translating as I go along while I'm looking for links to download,,nothing yet but I'll keep looking,,loads of links for different YouTube vids but no Layouts etc yet. Regards, Marty

[MartyJ1963]

Hi Dom,,,Hope you're having luck with your search,,,I checked all of MD.RU,,,,wasn't much on there,,but I found this site, don't know if you've checked it out yet but there's a lot of stuff on the Terminator there,,a lot of other interesting things too,,and loads of Layouts, files etc to download.http://forum.cxem.net/index.php?/top...0%D0%BC%D0%B8/
http://forum.cxem.net/index.php?/for...5%D0%BB%D0%B8/ I hope you find something!,,,Regards,,Marty

[MartyJ1963]

Hiya Dom,,,Hope your search was successful,,,I'm still looking. Could you tell me what value this capacitor is please? Hope you didn't mind me re-tracing your layout, I just filled out the solder areas a bit, it uses more laserjet ink but saves on Ferric solution when I'm etching. Thanks. Marty

[dom44]

10uf is fine Marty here is a small clip of it working before you ask its a cheap ebay 1.5v to 5v converter board wanted to see how well it worked on one cell works fine draw from battery 50ma goes to 100ma when beeping not a lot of gain with coin distance but looks more sensitive to small metal objects, still an intermittent problem with stability goes into random beeping now and then but works most of the time.

decide to go with Terminator trio looks like a good detector doesn't suffer from masking can detect a coin amongst 5 nails in one clip i watched thats very good still haven't worked out all the switches on it yet have to do more reading.

https://www.youtube.com/watch?v=rAlw...ature=youtu.be

[MartyJ1963]

Hiya Dom,,,Hope you had a good weekend,,,I finished building my PCB,,not tried it yet,,goot to nip out shopping in a short while so I'll try it when I get back. 'll take some photo's to show you what I've done. Having trouble with the coil though. I fnished the coil last night and wred it up to the Oscope. The frequency was about 329 khz,,,I did 40 winds then 200 winds of 0.25mm copper enamelled wire. I tried various capacitors to see if could get the frequency down to 20mhz but so far, no luck doing it. To get it down to MHZ range the capacitance was going intoo the high 'UF's',,,and the only capacitors I have left are Polarized Tantalum caps,,can I use Polarized? Still learning,,lol. I placed a 10uf cap like you said, I noticed what is was from the schematic cos' it was the only component not labelled on the Layout. I downloaded your clip,,,love the sound of it! Do you think that the instability could be because of the Ferrite rod the coil is built on? I remember reading that a lot of people who built Eddy's FM/FM2/FM2 V2 were having problems with ferrte coils,,a lot of people over came this by building air coils. I made a sort of Rectangular coil (with rounded edges), about 1" wide by 3" long and it works great with my first FM2,,,the only problem with it was, because it wasn't solid/rigid (resin coated), it flexes a tiny bit,,you sometimes have to squeeze it/shape it, when you first turn it on, so that neither the 'green' led or the 'red' led blinked. When both LED's were stable and not blinking at the start it works and detects great. The Inductance of that coil is 2292mh. The inductance of the coil that I've made for your version of the FM2 (40 turns/200 turns) is 40 turns=0.700mh,,200 turns= 2.72mh,,together the inductance is 2.75mh with a resistance of 3.3 ohms. Can you suggest a capacitance that I can try to get it down to 20mhz?,,Or should I make another coil with a higher inductance? I've tried tons! What is the inductance of the coil you used in the video? Thanks Dom,,,Regards, Marty.

[dom44]

Are you driving the coil with the built FM2 circuit or the testing drive circuit you have? It took me 4 capacitors in parallel at first to get the frequency right then i replaced them with one 10n green-cap works fine now the instability is only now and then thing is it is intermittent if it was the coil it would be all the time but it is not turn it on 3 or 4 time and works great,
turn it the 5th time then random beeps almost like its an outside RF problem or a software problem mind you I still have the test pot connected and the lead length could be the problem, but as you can see in the vid works well something wrong with yours if you need uf capacitors to bring the frequency down as i said mine oscillated at about 220khz without a cap and driven by the fm2 circuit.
the video i took is not even full sensitivity the knife blade normally would be picked up at least 1.5" further away but this time it was what you can see, its very strange i am tending to think its a software problem some kind of glitch like i said only now and then.

[MartyJ1963]

Hiya Dom,,,Firstly ,I've got to check my PCB for faults cos' it's not powering up at all. You're preobably right about the software cos' I checked my first FM2 (Eddys) both on the bench and out in the yard away from anything electrical or metallic and it gave me the same results. Thanks for letting me know about the 100R resistor instead of the 47R for the 8 ohm speaker,,I changed it out on my first FM2 and I now have sound! I'll check it all through and try it again and let you know if I've got it working,,,Thanks again Dom,,Regards,,Marty.

[MartyJ1963]

Hiya Dom,,,I've had a good look at my PCB and can't find any faults on it,,,I cleaned all the flux of the board before I powered it up. I checked all the component values before I placed them(Cos' I always measure them with DVM,write them down and tick them off), the transistors are all oriented correctly,,,Which 2N222 dd you use? I used the plastic ones,,,I checked my capacitor ratings and orientation,,,,,and I checked my wiring etc and there's no solder bridges,,I can only assume there's a faulty part somewhere,,,I etched 2 x PCB's so for now, I'll just make another one cos' it'll be quicker for me to do than take parts off the first one to check them. Thanks,,,Marty

[dom44]

most important thing make sure you have about 3.3v or so emitter of T3 without that nothing going to work if you do the other pos problem is the crystal oscillator i think eddy has the 220k resistor marked as may need adjusting in value if that doesn't work again nothing will happen the coil oscillator stage works on its own but again wont work without power from T3 the PCB is correct if you have a component tester check transistors lead orientation as i have had some brands with different connections I have wasted much time on some circuits only to find the connections are not standard as marked on data sheet. now as standard practice i use a component tester to check the parts before i solder in saves a lot of time.

[MartyJ1963]

Hi Dom,,,,Thanks for the help. I'll give it all a good thorough check again and test the voltage at T3. A little busy doing 'chores' at the moment but should have it checked again by tomorrow. I have made a new coil for my first FM2,,,I added a few more turns of wire to it and a 82pf cap and it works brill! I'm going to put the pcb into a small enclosure and make a leather pouch for it with a belt loop and attach the coil to curly long wire (like on headphones) and make a a plastic 6" x 1/2" inch tube to enclose the coil as a probe. I'll test it outdoors and if everythings ok I'll post some pics. Thanks again for the help Dom. Regards,,,Marty

[MartyJ1963]

Hiya Dom,,,Did you decide which Terminator your going to build? I was looking at the Terminator Trio but there's that many different layouts I don't know which one to try,,lol. I've not found anymore yet on the Terminator Prospector yet but I'll keep looking. Regards,,,Marty.

[dom44]

yes have started it board almost populated need to make the coil , started testing audio stage works and power stage, it works fine needed to tweak a resistor value in the power supply but so far so good i am building the prospector version.