Glad to get back to data-taking, even if it is with my colleague's BitScope lap-top oscilloscope (home-town, not at the University).
I decided to look at the phase relationship between the input voltage and the output voltage in the Tseung circuit. Straightforward and simple, right? the scope says otherwise, and I still don't understand the 2nd result. Conditions as follows, using Lawrence's Prototype A which he sent me. All voltages and currents are RMS. The only change between the two runs was the resistance of the output-circuit resistor, which was in series with the output LED. Incidentally, we found that the resistance of the output LED was approx. 200 ohms (from the voltage drop and current).
Output R Input V (AA battery) Input V across 1ohm Output V Output current (using 100ohm OR 1ohm) Frequency of oscillation 100 ohm 1.48 V 0.119 A 3.35 V 9.7 mA 69 KHz
1 ohm 1.48 V 0.112 A 2.96 V 26 mA 61.5 KHz
These voltages/currents are shown as a way to make comparisons with a "small" change in the circuit (output resistor).
Note that with the change in output R, the major change was in the output current while the input V and input current did not change much, and the output V changed by about 10% while the output current went UP by a factor of about THREE. Strange... We've noticed this before while trying to "tune" the Tseung device. Who can explain this??
Notice that the frequency of oscillation dropped with the drop in output R from 100 to 1 ohm. Conclude: The most sensitive indicator of change in the circuit is the output current, along with the frequency.
But even more striking is the change in phase relationship between the input oscillation (measured across the input resistor, always 1 ohm in this test) and the output oscillation (measured across the output resistor, 100 ohm {left} or 1 ohm {right} ) -- which we see in the attached. I have juxtaposed the signals from the input resistor (yellow trace) and output resistor (green).
We see that the voltage spike in the output circuit (see left traces) begins when the current across the input resistor drops rapidly. This is what I expect from the inductive coupling in the toroid. On the right, we see the traces for the case where I replaced the 100 ohm output resistor with a 1 ohm output resistor. Strangely, the output current rise appears now to LAG SIGNIFICANTLY behind the current-drop in the input R. I don't understand how this change in output R could have such a large effect in the phase relationship; and I'm wondering about our scope here. But it seemed to check out... could not find a problem in the scope. Would still like to re-test with a different scope.
Can you explain the phase shift, MH or anyone?
Again, I find that this is a most educational circuit, and intriguing. (Thank you, Lawrence, for sending the prototype to study.)
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