Still enjoying variations on the LTJT circuit. It occurred to me that the output shows alternating currently clearly, and so I put TWO LED's on the output circuit, in parallel, biases reversed. As I expected, they both light up -- using red LED's. In fact, subjectively I can say that the two LED's glow roughly the same.
Then, using my ATTEN 60MHz DSO to look at the INPUT power (using the math function *), I find that the Pin waveform goes from saw-tooth to approximately square wave (with two LED's in the output circuit). Calculating the input energy as I described before, the input energy (and power) approximately doubles.
When I remove the added LED from the breadboard-circuit (easy to do), I get the sawtooth on the input Power we are familiar with. When I remove the OTHER LED, the pattern is quite different, more of a skewed rectangular tooth. (I still don't have the ability to bring the waveforms here to the forum from this new DSO, sorry.)
Note: one must exercise caution when installing the output-circuit-LED if one uses only one. Clearly for a white LED, one direction is much brighter than the other bias-direction.
It's all very interesting and instructive. I'm using a toroidal inductor I purchased from Jameco, 100 uH with 34 windings I counted, this for the secondary, then I added thirteen (paired) windings for the JT-windings, wound by hand.
Yes, I have done a rough calculation Ein and Eout from the Power functions, in and out, integrating crudely over time (by hand). This DSO displays the Power waveform but does not calculate the average of it for you, so I do it by hand. A bit tedious, but I get a close look at the waveforms this way. I also double check the frequency. The best COP I've obtained for this particular set-up (Eout/Ein for one cycle) is about 0.85. Of course, I removed the transistor-LED out of the circuit long ago.
MileHigh -- would you expect the frequency to go up or down when I add a second LED to the output-circuit as described?
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