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I bought a AF-108 mine detector last week,and I got it in the mail yesterday,so I took it out and tried it.In my opinion the tick frequency is really slow,and its slow to respond to targets unless they are of substantial size,like a sickle bar mower blade for example revs it up pretty quick but a penny takes enough time to tick that you would walk right over it.In the owners manual it says the machine will detect aluminum cylinder 10mm tall,8mm diameter I believe it said at 20cm. and I believe it will but its too slow to signal. I butted a yardstick against the coil last night and used a beavertail pulltab for my test. I held it parallel to the coil and slid it down the yardstick and it will start to click at reasonable depth but very slowly maybe on tick per second at max detection depth. Does anyone have experience with these machines here? I'm sure we can modify the control to get better results.Any help will be greatly appreciated,thanks.
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I think the AF-108 was produced by White's/UK. We have 3 of them in Sweet Home, I was not very impressed with it compared to other PI's, but I don't know much about the needs of mine detection so there may be reasons for its behavior. I do know it uses bipolar pulsing but not much else. I'll see if I can dig up anything.
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Yeah I know what you mean, I wasnt terribly impressed myself. However I took it out today and played some more and its growing on me. Very very important to find a spot with no metal when you push and hold the auto tune button,took me a couple of trys to get it right but when I did It ran silent until you approached a target and if it ticks one time while you are walking/swinging you inspect it and there is a target.I was able to gage the size of some targets,and picked up some pulltabs with it. I love this website,I have some serious reading to do, what advantage does bipolar pulsing have if any?Originally posted by Carl-NC View PostComment
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Bipolar pulsing is a requirement of mine detectors so they don't generate a net magnetic field and set off a magnetic trigger. It has the added benefit of reducing external interference and canceling the Earth magnetic field. The drawback is that the TX circuitry is harder to design.Comment
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I hope to scare up a schematic,the coil has more wires going to it than I had hoped for.I know its got an led in it too so that may be all it is. I hope its just a mono coil so I can experiment with some other size coils.Comment
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af-108 mods
Hello Carl I was wondering if you looked into that old whites af-108 schematic? I was at Barbee's the other day,I bought a vx3 to try out. Your name came up in conversation,I would like to whip this af-108 into shape for pulling buttons out of my lovely NC red clay.Originally posted by Carl-NC View PostComment
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Honestly, I forgot to look into this. I'll see what I can find.
How's Jerry doing? He's a really great guy, I miss visiting with him.Comment
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Thanks Carl
He seems to be doing very well,I will see him again friday he ordered a coil for the new machine.I like that fella,he is good as gold.I have some sites now with great potential and little trash but the red clay is hard packed for long time apparently. I dug a merc,v-nickel,and an NC Seal button there.The merc wasnt deep and gave a terrible signal,I think the ground is just that hot.I think a PI is the right tool for the job.I guess we are looking for a sample delay trimpot on the af-108? I see it has 6 trimmers on the board.This machine is just too cool to be a slacker.Thanks for the help!Originally posted by Carl-NC View PostComment
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