Tweet
I never had one of those "minesweeper" demolition sets as a kid.
When I see them these days in person, they're usually non-functioning, have parts missing and/or they're broken.
If they're in good condition and functional, they're priced way out of my comfort zone.
I always wondered how they worked.
I looked online to see how it worked... searching for descriptions or schematics and the like; I didn't find much.
Then I ran across this little kit online... a "metal detector."
It was tiny. Ran off a 9v battery. Hmm... it might work for Joe!
I forget what I paid. $9? $14? I forget. But it looked cool, so I thought I'd try it. The kit was easy to assemble (maybe 15 minutes, max), and I tested it out. It worked great!
When you get the coil near metal, the LED lights up. There is a provision for a little buzzer on the board, but it wasn't included. I can always add it later if I feel like it. IMHO the red LED light is fine.
I built it just like the picture you see on the box above.
But that wasn't the right "form factor" for a Joe mine detector.
So I added a 4-wire extension cable between the circuit board and the pickup inductor.
The length of the cable was carefully chosen, because it was the only set of wires I had in my junk box.
Now I needed to find a way to put it in a backpack.
All of my soft backpack ideas didn't work out. Gutting a field radio wouldn't have given me quite enough room.
So I opted for a little box; it's a plastic box that some .311 bullets came in.
It was the size of a fat backpack, but would hold the circuit board and a 9v battery nicely.
You can see I made the LED poke out the top of the backpack. The wire bundle exits the pack just behind Joe's right shoulder.
I added a SPST power switch to the top.
Not visible in the pic are the slots I cut to thread an elastic fabric for shoulder straps (like the field radio has).
Although it wasn't finished yet, I sized it up on a Joe, and liked the size and look.
I tested it out again after all of my modifications, and it still worked great (so I didn't goof anything up).
Obviously I'm going to have to fabricate some kind of wand-sweepy-pizza-boix-on-a-stick for it.
I found a thick straw that was a perfect length laying in front of Joe in the pic above.
Figured I can thread the wires down through the straw and to the inductor.
But before I do that, I need to figure out what kind of disk I'll put on the end of it to house the inductor.
I may have to scratch-build something out of sheet plastic (a rare substance --- almost like Unobtanium!).
Maybe I'll find something I can recycle. Anti-freeze container lid? Small mustard jar lid? I dunno. It has to be plastic, though.
The mine detector is only held on Joe's back with a rubber band for now.
I need to put together an elastic for shoulder straps, but this rubber band was fine for my mock-up and for testing my "proof of concept."
The coolest thing is that this actually works -- and it works VERY WELL!
I can bury "mines" in the sand out back and sweep the inductor over it, and the LED lights up brightly.
I've tried it with fender washers and tin can lids. Both work pretty well.
Maybe we'll use fender washers for anti-personnel mines and the tin can lids for anti-tank mines (modern openers cut the lid off without sharp edges, so they're kid friendly).
It's not finished, but all that is left is the fiddling (backpack straps and finishing the "sweepy pizza box on a stick" cosmetics).
Then I'll give it a coat of flat Olive Drab paint and declare victory!
- ATC
When I see them these days in person, they're usually non-functioning, have parts missing and/or they're broken.
If they're in good condition and functional, they're priced way out of my comfort zone.
I always wondered how they worked.
I looked online to see how it worked... searching for descriptions or schematics and the like; I didn't find much.
Then I ran across this little kit online... a "metal detector."
It was tiny. Ran off a 9v battery. Hmm... it might work for Joe!
I forget what I paid. $9? $14? I forget. But it looked cool, so I thought I'd try it. The kit was easy to assemble (maybe 15 minutes, max), and I tested it out. It worked great!
When you get the coil near metal, the LED lights up. There is a provision for a little buzzer on the board, but it wasn't included. I can always add it later if I feel like it. IMHO the red LED light is fine.
I built it just like the picture you see on the box above.
But that wasn't the right "form factor" for a Joe mine detector.
So I added a 4-wire extension cable between the circuit board and the pickup inductor.
The length of the cable was carefully chosen, because it was the only set of wires I had in my junk box.
Now I needed to find a way to put it in a backpack.
All of my soft backpack ideas didn't work out. Gutting a field radio wouldn't have given me quite enough room.
So I opted for a little box; it's a plastic box that some .311 bullets came in.
It was the size of a fat backpack, but would hold the circuit board and a 9v battery nicely.
You can see I made the LED poke out the top of the backpack. The wire bundle exits the pack just behind Joe's right shoulder.
I added a SPST power switch to the top.
Not visible in the pic are the slots I cut to thread an elastic fabric for shoulder straps (like the field radio has).
Although it wasn't finished yet, I sized it up on a Joe, and liked the size and look.
I tested it out again after all of my modifications, and it still worked great (so I didn't goof anything up).
Obviously I'm going to have to fabricate some kind of wand-sweepy-pizza-boix-on-a-stick for it.
I found a thick straw that was a perfect length laying in front of Joe in the pic above.
Figured I can thread the wires down through the straw and to the inductor.
But before I do that, I need to figure out what kind of disk I'll put on the end of it to house the inductor.
I may have to scratch-build something out of sheet plastic (a rare substance --- almost like Unobtanium!).
Maybe I'll find something I can recycle. Anti-freeze container lid? Small mustard jar lid? I dunno. It has to be plastic, though.
The mine detector is only held on Joe's back with a rubber band for now.
I need to put together an elastic for shoulder straps, but this rubber band was fine for my mock-up and for testing my "proof of concept."
The coolest thing is that this actually works -- and it works VERY WELL!
I can bury "mines" in the sand out back and sweep the inductor over it, and the LED lights up brightly.
I've tried it with fender washers and tin can lids. Both work pretty well.
Maybe we'll use fender washers for anti-personnel mines and the tin can lids for anti-tank mines (modern openers cut the lid off without sharp edges, so they're kid friendly).
It's not finished, but all that is left is the fiddling (backpack straps and finishing the "sweepy pizza box on a stick" cosmetics).
Then I'll give it a coat of flat Olive Drab paint and declare victory!
- ATC
Comment