mini-Tesla

[BEP]

@EMdevices,

Notice where the crack happens?

It looks like the place where the wave has to change direction. Is that true? Or is that where the sent and reflected waves meet? I can't be sure from the photo.

Bep

[AhuraMazda]

@EMdevides,

Your mini Tesla coil is very interesting. I think it deserves it's own thread.

[k4zep]

I vote for a thread for the "mini" tesla coil.

Ben K4ZEP

[EMdevices]

thanks for the comments guys. Here's more info.


Frequency:

I perfected my Collpits oscillator and achieved a milestone for my breadboard, up to 25 MHz. 

Previously I had been around 1 MHz, but with some carefull observations and tweaking I got it fine tuned so it will oscillate that high.   For those versed in the RF arts, stray capacitance, parasitic component capacitance/inductance and other reactances we don't normaly consider at lower frequencies, start to attenuate the high frequency signals and it puts a stop to oscillation (kills the gain of the feedback loop, etc..) if you don't know what you're doing.  The breadboards are notorius for that with the many embeded strips of metal.  Anyhow, that's my operating frequency,  although, I was surprised to see so many different harmonics, just like Doc Stifflers pickup probe.   If the Tesla is not connected to the Collpits oscillator the waveform is a beautiful sine, but once it gets connected all hell breaks loose.   

Power in/out:      

I did not have the time to measure power in (or out) last night, I was so excited when that neon lighted up, I went for my camera took the two photos, and then POP !!!  the lightbulb busted in 10 or 20 seconds.   Good thing I took the photos when I did.   I think the breakage happend due to heat expansion of the glass, since it was constrained by the roll of electrical tape, and stress developed at the joint.  I had to push in the bulb a bit harder than I wanted too in the tape roll,  it was almost the same diameter but you know the tape can stretch a bit.   Anyway, I'll have to take apart another busted bulb (and I have another one that probably fried it's electronics just like this one had) 

Further Comments:

I'll post a circuit diagram later when I get home. I know from memory what I did but I want to be sure.   I'm using a mosfet attached to the black square heat sink that the tesla coil sits on, and I use this as the output stage.  Then the signal is generated by my breadboard and you see on it a golden coil that's upright, that's the main inductance that sets the frequency, and I can slide a ferrite rod through it and fine tune the coil even more, just like Tesla's magical box that powered his electric car (he pushed in a few iron rods to tune his internal oscillators)   

So is this related to Dr Stiffler?  I believe it is.  Like I said before his circuit resonates the secondary coil and that's what Tesla did.   Size realy doesn't change things, you just increase the frequency to compensate.   Anybody that has played around with Tesla coils and resonance will reconginze what Dr Stiffler is doing.   I admire his reseach and I believe he found a new way to excite the seconday resonant coil, and like I mentioned before it's through capacitance rather then inductance.   I will be trying that excitation method in the near future on this mini Tesla coil.  It could make for a cleaner and easier setup.  So its like talking about two different driveing methods of the same thing, the same coil.  Yes they are different if we get down to the details, but as far as energy it's the same phenomena.

If you guys want, we can move it all to another thread. I just placed it here since it was Dr Stiffler that pulled me back into this line of research, and yes I am making a point that you can get lots of power from RESONANCE of a LITTLE coil, but we will have to have some quantitative mesurements that will be coming soon.

EM

P.S.  This part of the thread was moved from the Dr.Stiffler thread to over here.

[EMdevices]

Here's a circuit diagram, I drew it from memory, but I think it's correct, if it's not I'll modify it later.

thanks for moving the postings over here, Stefan.

EM