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Old 02-04-2010, 05:24 PM
witsend witsend is offline
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Join Date: May 2009
Posts: 1,881
Regarding the tuning.

In tuning this device to 'find' that harmonic I adjusted the pots to the point that it fell into what I referred to as 'flop mode'. At this stage the 'predetermined duty cycle' is overridden as it's described in the Quantum paper. And also at this point the waveform becomes aperiodic. Thereafter I looked for the 'picket fence' which best describes the harmonic. When this is also evident, I then made reference to the DC average voltage across the shunt and the RMS voltage across the load, with multiple waveforms for reference on the Fluke screen. In initiating a test I also collected data from a data dump and analysed this in exel. Then, when I had established the required parameters I would then run the experiment to gauge the level of heat on the resistor and the rate at which the battery was measured to lose its charge. I would do periodic data dumps of the voltage across the shunt to establish that the gains persisted. But I learned, as time went by, that provided the required waveform was evident I really did not need to do those regular data dumps.

Over the years I also used a variety of resistors and found that the coefficient of performance, the resonating frequency which it developes and the 'preferred mode of oscillation' as we have now elected to call it, varies greatly with the resistor that is being used on the circuit. There are those that require a higher initial duty cycle, and those that require a smaller duty cycle. There are resistors that do not seem to give a gain at any frequency and those that always give a gain at any frequency. The very best result was the result published in the Quantum Magazine that I referred to being a technical journal and available in South Africa.

This variation in perfomance is extreme - notwithstanding the often apparent slight differences between any two resistors. I can only conclude that this is because the of the variation in the inductance and self capacitance of that resistor and the manner in which this interacts with the other circuit components. It is to be stressed that the required waveform cannot be imposed on the apparatus. The circuit finds its preferred mode by careful tuning of the adjustment potentiometers. It then - when it is close to the required duty cycle, goes into 'flop mode'. You remember this is when the duty cycle is overridden. Then some more fine adjustments and one seeks out the 'picket fence' pattern in the waveform. You will all recall that Glen's first evidence of gain was his Test 3. The 'picket fence' was evident. Test 4 - albeit having the required parameters failed. And there was no evidence of that 'harmonic'. I never even did the data dumps related to that test. I did not need to. It was immediately evident that the test had failed. At the time I did not know how to explain what was required. I simply did not see the 'shadow' which was evident in Test 3. I advised Glen directly that this was missing that harmonic. It's posted in the thread.

Last edited by witsend; 02-04-2010 at 06:07 PM.