Simple RF power oscillator

Buy a crystal oscillator and connect a wire to the output. Choose frequency with care.

You're not going to get power out of those.

The original poster has made the classic mistake of not providing any background. He "knows what he wants" yet in reality doesn't. Until he can provide the actual use of the oscillator, he's not going to get useful answers.

Michael

frequency

Ah yes I didn't spot the word "Power" in the OP.

Perhaps he's trying to duplicate what MIT recently announced... Another way to waste power and contribute to global warming...

That doesn't sound all that new. Circa 1974, there was a project in "Elementary Electronics" for an "electronic key" that got power when it was close enough to the main unit to get power through inductive coupling. Admittedly that news story seems to be talking about greater distance.

Actually, the original post reminded me of a previous one, where someone was wanting to build a plasma ball or something and was having problems getting real power out of the unit. I can't recall which newsgroup it was in.

Hi Michael Black and CWatters,

I know of the MIT wireless power transmission but in my modest opinion actually it is not so safe until today (5% of unwished far field is present in their evanescent wave experiment).

My need is more close to

technology.

I try to describe what I've in mind. Suppose a RF oscillator (e.g. Colpitts) which a LC resonator working at few MHz. The inductance L should be a simple loop of copper wire (one turn with diameter of about 0.7 feet). Placing near this loop another little LC resonating at the same frequency the RF energy will be efficiently transferred in this last one. If, for example, the power oscillator is about 5 watt, the transferred energy is able to light up a little bulb (for example). While I've experience with antennas, high Q LC etc. I've not a scheme for that type of oscillator. In my modest opinion it has to be as much as possible easy, just to begin some experiments. Probably, as written by Michael, the oscillator that I'm looking for is similar those used for plasma applications. Thanks to all you for your courtesy, Antonio

I'd look at some older ARRL books (1950's) for MOPA (Master Oscillator Power Amplifier) transmitters using vacuum tubes. You get decent power, and they can take a beating when it comes to mis-matched loads.

David, VA3DKS

snipped-for-privacy@gmail.com wrote:

Do you ever have anything useful to post?

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Michael A. Terrell
Central Florida

Before of all I wish thanks all you for your useful answer. Our different time zone delays the discussion, but this topic is very intersting for me ;)

x Charles: yes, probably I've need of a solid state Tesla circuit!

In other word making a solid state Tesla oscillator (let me say

10-20watt) and stop it at the primary coil I will have what I'm looking for. In fact on the "few turn" primary coil there is a strong variable magnetic field that's excellente to experimentate the RF induction.

Just two question:

1) Are there simple solid state Tesla circuit just to start to do experience? 2) Are there solid state Tesla circuit working at frequency beyond 1 MHz?

... and, IF YES someone can kindly post the scheme or link?

Thanks a lot in advance Antonio

Use Google search terms: "solid state tesla coil" AND circuit AND schematic, Turns up 65 hits

Simple? is in the eye of the beholder . . .

There are some mosfet ham radio output stages that use a mosfet driver chip that output 40-50 watts of carrier for an AM transmitter - but simple?

If I wanted a SIMPLE power oscillator in the 100 KHZ range, I'd get a pair of power transistors with a good high frequency response and wind a simple air core center tapped coil and use the more or less ubiquitous push-pull, cross coupled power inverter circuit to drive the tank circuit.

See: He's done just that

If I wanted SIMPLE I'd start with the 1962 "RCA Transistor Manual" for some ideas. They have schematics for a very simple 100 Khz (kilo cycles in those days) ten watt oscillator that uses a single germanium (!) transistor with a 28 volt supply and besides a tuned tank uses only one resistor and one capacitor.

Put a silicon transistor into the circuit and boost the voltage and you have a 50 watt oscillator . . .

They also show a 28 KHZ oscillator for 5 watts.

Again scroll down the page and there's the pretty close to the '62 transistor manual oscillator using one mosfet with an input power of

180 watts.

I can scan and post the '62 schematic to alt.binaries.schematics.electronics if you want, but you are just not searching hard enough or effectively enough - the stuff you want is on the web.

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When did a multivibrator become "push pull?"

When did an Eccles Jordan multivibrator have a transformer in the plate circuit?

Push pull toobe output stages are similar - pp mvb shocks one side of the inductor then the other. A rose by any other name.

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They had them there whenever wanted. That you have not seen them deployed in that manner, means nothing. It's still a multivibrator.

Similar only if you don't look close enough.

Well, yes, but that is no rose.

Hi Default,

I wish tank you very very veru much ;) The links that you've posted are a rich repository that I was looking for. My problem wasn't the weak or strong effort to search , but the fact that my search keywords was wrong. In fact, if you put in google the string such as "power oscillator" you will find a lot of accademic paper, patents and so on, but nobody pratical scheme. Conversely if you put "Tesla coil" in google you will find what you've need.

So, speaking with you and the other friends of this group the term "Tesla coil" is suddenly emersed and my problem solved ;)

Thanks again, Antonio

Invest in a copy of the Amateur Radio Handbook, published by the ARRL. There are many examples of simple oscillators, and a lot of theory explained.

If you can get an older version from the 1970's to the 80's, the circuits may be less sophisticated.

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