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25CommentsKokomo, Indiana, USAJoined September 26th, 2014

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector5 days ago
    Simple Arduino Metal Detector

    Great time on your several comments, Just yesterday I posted more of what I'm doing on http://www.buchanan1.net/md_1.html I was going to come here and post a link to it today. So there it is, with schematics and screenshots from a 'scope.I wound up redesigning the oscillator, I just wasn't pleased with the one from the other article. rgco's idea was great, this circuit is much more sensitive. A lot more complex though. I guess I forgot about the possible internal comparator and used an LM339. I just looked it up, it is a thing, I might try that before I finalize my design.I'm planning another article after I build an actual practical unit. Maybe an Instructable too, I've never written one, it looks like fun.It'll probably be a while, I just ordered a 3D printer that will take up a lot...

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    Great time on your several comments, Just yesterday I posted more of what I'm doing on http://www.buchanan1.net/md_1.html I was going to come here and post a link to it today. So there it is, with schematics and screenshots from a 'scope.I wound up redesigning the oscillator, I just wasn't pleased with the one from the other article. rgco's idea was great, this circuit is much more sensitive. A lot more complex though. I guess I forgot about the possible internal comparator and used an LM339. I just looked it up, it is a thing, I might try that before I finalize my design.I'm planning another article after I build an actual practical unit. Maybe an Instructable too, I've never written one, it looks like fun.It'll probably be a while, I just ordered a 3D printer that will take up a lot of my hobby time, plus I intend to use it to make some of the physical parts for the unit.

    Elsewhere in the comments, I posted some work I'd done to increase the range. I increased the sensitivity massively but made the circuit far more complex. rcgo suggested a way to reduce the complexity, I'm going to try that in the future. I'll post about that here in the comments.

    I could see the differnce between ferous and non-ferous metals when I built it.

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector1 month ago
    Simple Arduino Metal Detector

    I just built the oscillator on the left side of that schematic. It works well, and did on the first try. Just looking at the frequency measurment on my 'scope, it seems a lot more sensative than either of the inductance measurement methodsSorry I'm taking so long to reply, I have a lot of other stuff going on...

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  • 10 Woodworking Tricks the Pros Use

    We didn't learn all of that in shop in Jr High either. I knew some of these, some my father taught me, others from books. Great instructable!

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  • Easy Rubber Machining With a Needle

    Looks good!I didn't know you could buy needles at a pharmacy without a prescription. I get my insulin needles with a prescription. I thought that they wouldn't just sell them in case the buyer was planning on using them for IV drugs...If I or my makerspace ever gets a CNC mill, I might just look into this, the possibilities are endless.

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector1 month ago
    Simple Arduino Metal Detector

    I just tried the full circuit using pulseIn() and an LM339 comparator. It's somewhat less sensative then your original circuit, as you predicted. I think I'll try the oscillator idea next.

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector2 months ago
    Simple Arduino Metal Detector

    I just looked at my comment and it looks like I said that I thought the frequency method wouldn't work. Sorry, I didn't proofread, it actually sounds like a very good idea...

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector2 months ago
    Simple Arduino Metal Detector

    Pretty much what I've been seeing. After I try with pulseIn() I think I'm going to try a PI detector too. I'm having a lot of fun here, thanks for publishing this!

    Thanks for the idea, I'll try that maybe after the pulsIn() idea. I don't think it will work either, I can hardly see a change on the 'scope when I move a smaller object close.

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector2 months ago
    Simple Arduino Metal Detector

    That sounds like a cool project. If you want, you can let me know how it goes at jbuchana@gmail.com Anyone else who wants to discuss this circuit may contact me as well.Even with the smaller coil, I didn't get the sensitivity that I wanted on smaller objects, and the distance at which I could detect larger objects was reduced. I tried a 40 turn coil instead of the 18 I was using for the 4 inch coil, but other than being able to raise npulse from 3 to 7 (for what that is worth), there was no appreciable difference.I had the idea to measure the pulse width from the 40 turn coil with pulseIn() directly instead of looking at the voltage on a capacitor. A little research showed that this would not work, the pulse was too narrow for pulseIn() I then had the idea to "ring" an LC circ...

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    That sounds like a cool project. If you want, you can let me know how it goes at jbuchana@gmail.com Anyone else who wants to discuss this circuit may contact me as well.Even with the smaller coil, I didn't get the sensitivity that I wanted on smaller objects, and the distance at which I could detect larger objects was reduced. I tried a 40 turn coil instead of the 18 I was using for the 4 inch coil, but other than being able to raise npulse from 3 to 7 (for what that is worth), there was no appreciable difference.I had the idea to measure the pulse width from the 40 turn coil with pulseIn() directly instead of looking at the voltage on a capacitor. A little research showed that this would not work, the pulse was too narrow for pulseIn() I then had the idea to "ring" an LC circuit and measure the width of the first half cycle with pulseIn(). I Googled this idea and found:https://reibot.org/2011/07/19/measuring-inductance...He's using a very similar method to measure the inductance of assorted coils but does mention that it might be used as a metal detector.I built part of his circuit up and am measuring the pulse width of the first half of the first cycle of the damped sine wave using a 'scope. Big objects make a huge timing change, smaller objects almost immeasurably so with the 'scope. I'll build the full circuit (probably without the diode, it seems to serve no purpose and the results I get are the same without it) and see whether there is enough time to do the job. I am getting what will be pulse widths of about 25uS with 2 0.47uF caps, well within pulseIn() capabilities. The amplitude of the first ring is about 250mV using a 150 ohm resistor, not enough to read directly with the Arduino. The comparator will be needed to get it up to logic levels. There is so much noise and 5V random spikes that I fear that the pulse output will not be clean. I'll have to look into a Schmitt trigger.

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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector2 months ago
    Simple Arduino Metal Detector

    No real improvement on sensitivity yet. I'm going to try different coil sizes soon, I was having trouble with instability, the detector going off for no reason. It turned out to be my fault, I made two mistakes. The first was the capacitor, as I noted above, it was an unknown ceramic. I replaced it with a polystyrene capacitor, no more sensitivity to air currents. I can blow on it, or even hold it between my fingers without the detector going off. There was still some random chirping going on though, both with a 5V reference and the 1.1V reference, I realized that it might be an unstable supply voltage, I was running it off of the USB port of the computer that I was programming with. I substituted a bench supply set to 9V and connected through the Arduino's barrel jack. The chirping tot...

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    No real improvement on sensitivity yet. I'm going to try different coil sizes soon, I was having trouble with instability, the detector going off for no reason. It turned out to be my fault, I made two mistakes. The first was the capacitor, as I noted above, it was an unknown ceramic. I replaced it with a polystyrene capacitor, no more sensitivity to air currents. I can blow on it, or even hold it between my fingers without the detector going off. There was still some random chirping going on though, both with a 5V reference and the 1.1V reference, I realized that it might be an unstable supply voltage, I was running it off of the USB port of the computer that I was programming with. I substituted a bench supply set to 9V and connected through the Arduino's barrel jack. The chirping totally went away with the 5V reference, it was still there with the 1.1V reference. The 1.1V reference is regulated on the chip, not provided by the power source, so it should have been stable even with the so-so supply voltage. I'll try that smaller coil next, and see if I can find any other ways to improve the circuit.

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  • jim.buchanan.165 followed rgco and jim.buchanan.1652 months ago
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  • jim.buchanan.165 commented on rgco's instructable Simple Arduino Metal Detector2 months ago
    Simple Arduino Metal Detector

    I just tried the 1.1V internal reference. I had to raise the resistor to 330 ohms to drop the capacitor voltage to about 0.9V, under the new reference voltage. The sensitivity was definitly improved, but not as much as I had hoped. About 25% better on a US quarter. The increased sensitivity caused some problems though. It's even *more* sensitive to capacitor temperature, and it seems to be triggerd by electrical noise, causing random clicks and blinks. I'm going to have to think about this more...

    I built a breadboarded version on the bench. It worked the first try. I adjusted the count up and down from the 3 counts in the original sketch. It did change the capacitor reading, I left it at 3, which gave a value of 273. Changes in the count didn't seem to affect the sensitivity. One problem I have is that I used an unknown generic .001uF (10 nF) capacitor from my junk box. I suspect it's a Y7R. It is *very* sensitive to temperature changes! air currents in the room change the value enough that the detector goes off with no metal around it. Putting an upside down cardboard box over the circuit pretty much stops that, but is impractical. I've ordered some better caps to solve that problem. With a 5 1/2 inch (14 cm) coil, it will detect a medium size piece of metal at about 3 inches. ...

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    I built a breadboarded version on the bench. It worked the first try. I adjusted the count up and down from the 3 counts in the original sketch. It did change the capacitor reading, I left it at 3, which gave a value of 273. Changes in the count didn't seem to affect the sensitivity. One problem I have is that I used an unknown generic .001uF (10 nF) capacitor from my junk box. I suspect it's a Y7R. It is *very* sensitive to temperature changes! air currents in the room change the value enough that the detector goes off with no metal around it. Putting an upside down cardboard box over the circuit pretty much stops that, but is impractical. I've ordered some better caps to solve that problem. With a 5 1/2 inch (14 cm) coil, it will detect a medium size piece of metal at about 3 inches. (7.6 cm) A US quarter gas to be about an inch (2.54 cm) from the coil for detection. That's not good enough for my purposes, I'm going to try some modifications. The first will be using the internal voltage ref of 1.1V [ analogReference(INTERNAL); ] To do this I'll have to make some circuit changes as the capacitor voltage hits 1.3V which is above the 1.1V internal reference. If I can get the sensitivity up, I'm going to 3D print some mechanical parts and build a permanent version. Thanks for a great instructable!

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  • 5 Ways to Remove a Stripped Screw

    If the screw's in metal, penatrating oil and some hard tapping on the head can sometimes loosen it enough that one of the other methods can remove it.

    The "Screwgrip" idea sounds very good, but I've never seen it for sale. What I use is valve lapping compound, and abrasive paste available at auto parts stores (or surely on-line) It's saved me several times. It's best used just as the head feels like it's stripping but before the head is totally ruined.

    I've sometimes drilled the head off, then pulled the top piece off. Then vice grips can grab the protruding shaft and take the remains of the screw out.

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  • jim.buchanan.165 commented on Nematic!'s instructable Capacity Test of Fake 186501 year ago
    Capacity Test of Fake 18650

    I wrote an article about testing the capacity of AA primary cells, I've documented it here:http://www.buchanan1.net/battery_test.htmlIt uses an Arduino to measure the discharge characteristics of the cells. A similar method could be used on 18650 cells, for those who are interested in watt hours, a small change to the post-processing software could be made. I used a Linux machine to run the post-processing software on, with thw Windows 10 Anniversary Edition, you can install the Linux environemtn and perl, and run it under Windows.

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  • jim.buchanan.165 commented on OrenK9's instructable Leg Vise1 year ago
    Leg Vise

    BTW, I made both of the mallets in the picture in the same time frame, they are both doing well. The joiners mallet is made from black locust with an ash handle, the octagonal section mallet is soft pine, it is used to hammer in holdfasts, so it's kind of chopped up -as intended.

    Whoever had the idea originally, hundreds or more years ago had a really good idea. I read about leg vises in a historical woodworking book more than 20 years ago before I decided tomake one, Those people had some great design concepts back then! They are very strong.

    Nice! I built something almost like this back in the '90s and I still use it years later, I even moved it to another bench when I upgraded the bench. I don't have a photo on this computer, I'll try and find a picture, or take a new one later when I'm at home to post with a description.I think you'll get years of use out of this project.

    I found a picture of it, a recent one, it's holding a prop musket my daughter and I are making for a cosplay outfit. She wasn't born when I made the vise!It is very similar, but quite different as well. As you can see, I used hardwood inserts on the jaw, and soft wood for the rest of this I took some real heat for this when I published it online, they said it would never last. I think almost 20 years proves that the wood choices were just fine!I hope that yours works for as long as mine has.

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  • DIY Hot Wire Cutter for Plexiglass, Cardboard and Foam

    Great project! I built one very similar to this in the mid 1980s. I powered it from a filament transformer, normally used in vacuum tube equipment. A filament transformer might be hard to find now... We used it in an MET class I was taking to cut foam for lost foam metal casting. I gave it to the school (Purdue in Indianapolis) when we were done with it. I also made one for freehand cutting from a coping saw frame. I kept that one, but lost track of it over the years.

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