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I built a crude copy and found interesting things. No, it's not a "cosmic energy collector."

Instead it's an extremely sensitive light-detector, from before the invention of phototubes. Also it picks up ambient voltages (e-fields,) and is incredibly sensitive to ion flows in air. It's a radio-wave detector from before vacuum tubes, even before cats-whiskers. Also, it should easily detect ionizing radiation (a primitive Geiger Counter, discovered three decades early.) Tesla's actual patent shows it being used as a “radiation alarm” which rings a bell whenever hit by beams of x-rays.

And it was discovered years before amplifiers existed. Only sensitive relays existed back then. And also, we had human ears used as detectors (Tesla’s “tickker” or “tone-wheel” in this invention converts micro-scale DC into a distinctly audible buzz in your earphones.)

The essence of this 1901 Tesla invention is to "chop" any electrostatic signals coming from a capacitor plate.

Tesla had patented the “tone wheel.” Years later, everyone was using it, but hooking it to a radio antenna, not to a metal sheet illuminated with ionizing radiation.

This device produces fairly enormous pulses, especially when the rotating switch is moving very slowly. Therefore very small signals can suddenly be heard by human ears (heard as sound in headphones. Two 1890-style telephone-speakers were Tesla’s headphones.) In the decade before vacuum-tube amplifiers existed, Tesla’s invention harnesses exquisitely sensitive human hearing as an energy-detector.

Also, unlike x-ray detectors such as phosphor screens or foil-leaf electroscopes, the pulses can become part of electronic products, where a weak electrical signal can slowly trigger a sensitive relay-coil (which Tesla calls "circuit controllers.")

While building one of these, I realized that very obviously this device is based on the Branly Coherer radio detector. But in comparison, the Branly Coherer has far lower sensitivity. Tesla’s device, rather than depending on the fairly high voltage-threshold of the coherer-effect, (where iron particles are being nano-welded, and also, rather than requiring a mechanical tapper to reset,) …instead Tesla’s version directly harnesses the Coherer concept. No metal grains, instead it employs the sudden closing of a moving switch to suddenly dump the capacitor-charge created by a tiny signal. The switch behaves as a single giant coherer-grain. Unlike the Coherer, Tesla builds his version out of macro components, with no metal powder involved. And, his continuous clockwork "tapper" is part of the detection, rather than being the reset-device of a conventional Coherer.

Since Tesla’s version needs no breakover-voltage (and so will operate all the way down to zero threshold,) and since it can be selectively slowed down to clicks-per-minute, it might be 10,000x more sensitive than Branly's Coherer.

If not more.

Along these lines, Tesla may have secretly intended this patent to be a radio detector, with a metal plate as a capacitive antenna, while Tesla carefully keeps this side-application secret, yet still being able to patent the device. So, besides detecting x-rays, it also functions as a Goldschmidt “Tone-wheel” or the "Poulsen’s Tikker" -style of radio detector (which was independently invented a decade after Tesla published these,) and served as a design fit for the VLF radio-band which Tesla was using at the time.

If you experiment yourself, using metal foil and buzzing relay-contacts, you'll find that your metal plate will be completely swamped by 60Hz environmental voltage-signals. Tesla never had to contend with today’s AC line interference! Better build yourself a shielded room? Otherwise, the plate must be enclosed within a small grounded shield. To detect ions or hard radiation, put a big window in your little shield, covered with a few wires stretched across the opening, or with coarse metal screening connected to the metal shield.

That, or move your lab waaaay out in the country, far away from all AC power lines.

Reading other descriptions of this device, I conclude that most explanations are loads of c**p, with the main mistake being misinterpretation of Tesla's term "Radiant Energy."

This term came from Tesla's hero, Prof. W. Crookes, and “radiant” energy (or “radiant” matter) means the same as our modern terms "ionizing radiation" or "nuclear radiation," possibly also including ultraviolet light and radio waves …all mashed together.

In other words, the patent-title actually means "Method for Detecting Ionizing Radiation." This was decades before the Geiger-Muller counter!

The second mistake people make is in not realizing that, at the time of Tesla’s patent, vacuum tubes and amplifiers didn't exist. Tesla’s invention is a major advance, when compared to many other sensors of that era: this is a Poulsen tikker connected to a relay coil, giving relatively immense output, in the form of slow pulses. (Tesla invented the tikker detector a decade before Poulsen publicized it. As with many of Tesla’s breakthroughs, it was “lifted” without attribution by others, and given their names, not Tesla’s.)

As a radiation detector, Tesla's invention was more sensitive than foil-leaf electroscopes or phosphor screens; the scintillators. In modern language, it's the first Geiger Counter, but invented decades early. It's also a voltage-detector similar to a foil-leaf electroscope, but automated, where its pulse signals are large enough to be used by electrical products ...or, for extreme sensitivity, detected as faint audible clicking-sounds in headphones. (Note that the patent *includes* the electroscope, where slowly-building electrostatic attraction causes a pair of lightweight delicate capacitor plates to pull together, shorting out and producing periodic pulses with frequency proportional to the strength of the detected HV signal.)

Also, this invention harnessed the photoelectric effect of metal surfaces, and would become charged when x-rays or hard UV would knock electrons out of the metal plate (coated in fresh-cleaned zinc, or wet mercury.) Tesla accidentally discovered the Photoelectric Effect? And even patented it?!

Today, everyone would instantly recognize Tesla’s invention if only he’d placed his detector-plate inside a glass evacuated (or argon-filled) tube, adjacent to another electrode. It's the Phototube or "electric eye," but invented here years before phototubes existed, and operated in open air with no sealed tube. It's the competition for the Selenium-Cell “electric eye” already being used at the time. It's the Geiger-Muller tube, but with no HV supply, and where its operating voltage is provided by the radiation striking its surface.

Is it an “energy” receiver? Of course. But, signal-level energy only. (Did Tesla say differently?) Photo-tubes don’t work as well as modern solar cells for gathering milliwatts, but both are energy-receivers.

Tesla’s device is more similar to the "Crookes Radiometer," with its spinning black and white paddles, in that it’s not intended for directly powering motors. Instead it's a Victorian Steampunk Geiger Counter. Or, it becomes the commands-receptor for drone-robots controlled remotely by narrow directed communication beams (tesla x-ray beams, since microwave beams didn't yet exist.)

• I want to build a simple form of radiant energy generator according to Tesla's patents (Patent US685957
• Does Nikola Tesla's proposed "radiant energy" generator hold merit in terms of providing free energy from the air?
• How was Nikola Tesla able to charge a capacitor from the Earth without diodes in the patent 685,957?
• What is Tesla's cosmic radiant energy?

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Quora Tesla index, see: How do I become as genius as Tesla? scroll way down

For lots more similar science-answers, see… QUORA ANSWERS: William Beaty

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