Mad idea

Yes - as you and I have discussed, it involves using ultrasensitive magnetic field detectors, like high-Q tuned circuits with SQUIDs - very narrow-band.

That scientist I mentioned last year is back in Australia and coincidentally, is coming to dinner tonight. He's the one who worked out how to make large arrays of SQUIDs (like 10,000) in order to get broad-band detection. That was hard because previous yields were around 30% for one.

Anything you'd like me to ask him? He probably can't answer anyhow.

Clifford Heath.

Reply to
Clifford Heath
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Fun, are the squids cooled to liquid helium temps? Or are there high TC squids that work well enough at liquid nitrogen?

George H.

Reply to
George Herold

I think LH, but I wouldn't know. The only squids I've ever seen were either on a plate or swimming in the ocean.

Clifford Heath.

Reply to
Clifford Heath

Why not a quadcopter?

You could have it explore raster grids under sw and GPS. With some local altitude sensing it could hug the ground, *regardless of the roughness of terrain.*

With a crude fluxgate magnetometer, you could locate all buried ferrous objects (waterproof cash boxes, nickel-iron meteorites.)

With a scintillator or a GM counter you could locate all shallow- buried dinosaur fossils (which exhibit preferential uptake of radionucleides.)

Do all at once. Then sell the maps.

(((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))) William J. Beaty

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beaty, chem washington edu Research Engineer billb, amasci com UW Chem Dept, Bagley Hall RM74 x3-6195 Box 351700, Seattle, WA 98195-1700

Reply to
Bill Beaty

Aerial drones that operate outside the line of sight of the operator and/or for commercial purposes (prospecting would probably fall in that category) are illegal for unlicensed hobbyist use in the US per the FAA

Reply to
bitrex

Just a couple of years after the first RADAR we made proximity fuses with 2 or 3 tubes, so why don't we have RADARs with a few transistors?

Reply to
Tom Del Rosso

Just a couple of years after the first RADAR we made proximity fuses with 2 or 3 tubes, so why don't we have RADARs with a few transistors?

Reply to
Tom Del Rosso

The oscillator isn't easy with a three-terminal device, generally Gunn or impatt diodes and other such exotics are used. I''m not sure what my orange Hot Wheels radar uses, but it'd be amusing to take it apart and see.

You could buy one and see

Reply to
whit3rd

This article gives a pretty good description:

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You can get the doppler modules on ebay starting at a buck:

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Reply to
Steve Wilson

On Apr 2, 2018, Tom Del Rosso wrote (in article ):

Because we are no longer satisfied with WW2 radar capabilities and performance. Nor are our enemies.

Joe Gwinn

Reply to
Joseph Gwinn

Nor our quadcopters?

Proximity fuzes reliably triggered explosives at the right distance when they were moving in a bullet.

Your answer is a non-answer.

Reply to
Tom Del Rosso

On Apr 3, 2018, Tom Del Rosso wrote (in article ):

It happens to be the truth, though. I do this for a living. I?d suggest reading some textbooks, like Radar Principles by Payton Peebles, Jr. A *lot* has happened since WW2, and WW2 technology simply won?t cut the mustard.

Joe Gwinn

Reply to
Joseph Gwinn

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He question was asking why we don't have RADAR in three transitors, but the proximity fuse he is talking about is *not* a RADAR. It only detected pro ximity. So the question is a bit of a non sequitur.

Rick C.

Reply to
gnuarm.deletethisbit

I wish he would just read the context of the question.

My question was in the context of a quadcopter "hugging the ground" which would require only proximity sensing. More than 3 transistors to replace 3 tubes, but it should be possible with a small number of parts.

Reply to
Tom Del Rosso

On Apr 5, 2018, Tom Del Rosso wrote (in article ):

Radar frequencies don?t go very far in wet dirt, and a VT fuse circuit (even if done with modern components) isn?t going to be very helpful.

I?d suggest that the original poster haunt the Pulse Induction Metal Detector fora. Pulse Induction works at baseband, has reasonable ground penetration, and is used for nugget hunting.

Joe Gwinn

Reply to
Joseph Gwinn

The idea wasn't to detect buried metal with it. Terrain following and metal detection would be separate systems on very different frequencies.

Reply to
Tom Del Rosso

build a radio transmitter with one transistor and measure the supply current with the other two (current mirror)

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This email has not been checked by half-arsed antivirus software
Reply to
Jasen Betts

If you wanted to do that and provided that the ground doesn't change too abruptly chirp echo location will allow you to do this fairly reliably. Speed of sound is fairly easy for time into short distances.

It won't work if there are vertical obstructions like pylons and trees or over excessively lush vegetation.

I suspect the problem for a quadcopter will be that there is already way too much metal, magnets and electrical interference for it to operate a metal detector underneath it with decent sensitivity. Perhaps a pair of quadcopters moving in tandem with the search coil suspended between them would get you something that might work.

But the traditional method towing a tethered coil on a simple bogey behind some sort of tracked vehicle seems a lot less difficult to me.

--
Regards, 
Martin Brown
Reply to
Martin Brown

The upside of a copter is fast coverage of a lot of terrain. Maybe if one went back to using a glowplug engine a lot of the interference would disappear. They're noisy though, and the fuel especially hazardous.

NT

Reply to
tabbypurr

endurance. Yes, magnetic disturbance too.

Why not an automonous blimp?

Clifford Heath.

Reply to
Clifford Heath

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