Dr Ronald Stiffler SEC technology

[Slider2732]

It is a good use and good video.
Especially the micro 'tower' which lends itself readily to boxing up and not knowing there is a Slayer circuit inside.
Hopefully you can carry on with the project though, if things take a turn


One of which might be this....
Have found a circuit here:
http://jaunty-electronics.com/blog/2012/08/simple-oscillator-as-crystal-tester/
A very simple and effective circuit for driving practically any 2 pin crystal !!!
It works wonderfully.
Have tested loads of them and all work, with a clean wave output at the correct frequencies.

Video of it running and a crystal swap is shown:
https://www.youtube.com/watch?v=2omcrkrrhoc
(2 mins 14 secs)

Now we just have to find a similarly simple way to get the signal to 20V 

[TinselKoala]

Run the output of the tester circuit through a Schmitt trigger inverter stage or two to square it up, then use the output from that to drive a mosfet driver driving a mosfet in a lowside switch configuration, switching your 20v through your load. Keep your circuit tight and solid (respect RF design principles). 

[Slider2732]

Thanks TK and that's where I got confused. A lot of mention was made of needing a Sine wave, so the only thing I could think of was to use a MOSFET and then perhaps add another slight tank to smooth out the sharpness of the squarewave.
Will take the MOSFET route in any case, it's the only one to readily produce the 20V

[gyulasun]

Hi Lidmotor,

Good result with the exciter, thanks for the video. Would like to ask whether a puffer capacitor across the LED at the output of the two AV plug diodes does not help increase brightness a little?  (Albeit it may also increase input DC power a little, too.)

You wrote:     "With what I have to work with and the results I have seen so far I don't see how he did what he did.  Driving that Cree board to the brightness he showed, with just a 13 MHz signal, is a puzzle."

No offense intended but you have not replicated the Doc's signal generator experiments yet. The answer is that your 13.5 MHz 4 pin oscillator has much less output amplitude than that of the Doc's signal generator, this is what is missing for you. The Doc starts with the 25Vpp or so amplitude and his air core coil enhances it at resonance up to at least the 70-90 Vpp or higher amplitude ranges and this is what excites capacitively the p-n junctions of the LEDs.

I do think that the exciter you just showed in the video may easily have the 70-90 Vpp or so at the top of the secondary coil, converted from the 3.7V battery (and the associated input current) by resonance and that is what feeds the LEDs via the AV plug.

The SEC 18 you used the other day should have similarly high RF amplitude across its coil and that is what you fed capacitively to the Alu plates of the LEDs and got good brightness too. Perhaps you could test this latter feeding method with the Slayer exciter too if you have not done so with that yet.

Gyula

[gyulasun]

Thanks TK and that's where I got confused. A lot of mention was made of needing a Sine wave, so the only thing I could think of was to use a MOSFET and then perhaps add another slight tank to smooth out the sharpness of the squarewave.
Will take the MOSFET route in any case, it's the only one to readily produce the 20V

Hi Slider,
Well, the Doc surely has his reasons to choose sine wave from the starting signal source for such test setups. 

It is possible that if you had a 25 Vpp square wave at say 13.5 MHz, then the air core coil driven with a single wire and tuned correctly to this frequency would also amplify that to the 70-90 Vpp amplitude which would already be a sine wave rather than square wave due to the resonance but this needs to be tested whether it gives similar result then a sinewave from the start. 

When I gave links to oscillator circuits, those papers included a 1 W and a 10 W linear power amplifier with MOSFETs, see this post of mine.  Both amplifiers are preceeded by a single transistor preamplifier and the latter could be driven from a dedicated 13.5 MHz crystal oscillator  or even from your already built LC oscillator. 

Gyula