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hoola

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About hoola

  • Birthday 06/17/1951

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  • Location
    colorado, usa
  • Interests
    electronics, music, theoretical physics, philosophy, politics
  • College Major/Degree
    none
  • Favorite Area of Science
    physics
  • Biography
    retired electronics technician, antique/vintage electronics collector
  • Occupation
    none/ recycling center volunteer

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  1. today I finished the edge contact - tube interface module and which now provides a high P-P tube plate signal, using a DC plate supply of 500V. The waveforms are clean and relatively undistorted and show the signal in it's pure state, as the secondary stack is not hooked up yet, only 90K load resistors from the high voltage supply functioning as dummy load. The bias is still in need of some refinement, as the bias setting is altered somewhat when driven by an appropriate signal. The overall cathode current seems low at this point, showing an averaged current of 5ma per tube with this robust drive signal voltage. The next test will be with the secondary set of piezos hooked into the circut hooked directly off the plates. I have eliminated the coupling caps between them as they seem unecessary as the the piezos are good insulators, and seem to have unexpectedly high capacitive value, as shown by my twin arc surprise of last month.
  2. The edge contact drive now delivers an accurate inverted output from the tubes plates after determining the correct grid bias setting, but at a low level that requires adding a gain stage for each tube input to deliver a useful output. Conventional transistors can be used for a 5 single channel amp board to be added onto the main driver chassis using it's existing power supply. This requirement was not unexpected as the tubes are low gain.
  3. Today I removed the matrix from the two sensor/turnaround elements of the original stack and looked at their outputs separately and can see more clearly the coorelation between maximizing assymetries in one element vs. minimizing assymetries in the other that sometimes occurs. A typical display seems to divide itself in half across a horizontal line, offering a "virtual zero reference line" and the two halves can be made to meet and form interesting relationships with the other as they do so, but only as they approach closely, as if they do meet, they tend to collapse into random noise, indicating a negation of any thrust signal possibility. A few distinct drive frequencies markedly, 115khz, 125khz and 161khz have the property of enhancing either a positive or negative overall assymetry, indicating a potential directional trust in one sensor element, coupled with a symmetry in the other, indicating a negation of phononic energy, and so minimizing the unwanted counter thrust to any potential thrust.
  4. today I hooked up 5 piezos in the edge contact method and got good signal output on all five. I placed one of the signals to the grid of output tube #1 using a supply voltage of 500V dropped through to a load resistor of 20K@25watts to the plate. The DC level of the plate measured +225V, so the AC signal at the plate is in the order of half that, or around 100V P-P. although this is an estimate, as the scope is rather dated and probably inaccurate, but a good outcome of this initial trial to drive the tubes in this fashion. The 20K resistor got hot, but not too hot to touch, so is in the ballpark of an appropriate load resistor, but is probably on the low side. The tube current is 10ma when not supplied with B+, representing the screen current. When the B+ was applied the total tube current increased to 20ma, well within the max ratings of the 6BG6 glass tubes. I have not hooked up this plate signal to the new stack yet, only have measured it's output, but will shortly have all five tubes in operation and driving the new stack. The tube I have tried first is an old RCA and probably 50-60 years old and checks rather weak on the B&K 707 tube tester, but not leaky or gassy. My intention is to replace these with NOS tubes when I have worked out all the details with the used ones.
  5. the next test will be with the "edge contact" method used to drive the tubes, as they do offer high isolation from the initial pulse. A properly designed electronic selective gate system could have a near complete isolation if desired, with the added benefit of having a control of relative values of the two signal strengths.
  6. Today I worked on the original stack, replacing the copper contact pads as the wire hookup tabs were beginning to fall off due to a year of constantly soldering and unsoldering them. I replaced the pads with the .006 copper as with the new stack, in a further attempt to equalized their responses when working in tandem. Tests done after completing today's repairs showed a closer correlation in the two displays when scan order is reversed.
  7. When you switch scan directions there is little to no correlations to the scope display simply being inverted, as one would think, as they are laid out with symmetrical spacers, washers, etc., instead they are almost entirely unrelated in appearances with occasional rare exceptions. I have yet to see a clear reason why this should be he case. Asymmetries in the torque within the stack seems responsible for some of it. These tests are done with all piezos on.
  8. Today's testing shows that the 1/4" polycarbonate is in itself very sound deadening, and may not need to be even partially evacuated during operation. The enclosure should preclude any false thrust due to acoustic pressure from the stack, as any should be neutralized, staying within the containment.
  9. The vacuum chamber is approx 80 cu. in. interior volume, and nearing completion. I have suspended the stack within it on a coil spring and so giving it more degrees of freedom of movement, not being fixed directly to the arm, now free to move in the vertical Y directions, due to the chamber being mounted on the arm, but also in limited amount in the X and Z directions within the chamber itself, and even to rotate if any forces should allow it to. I don't think I will need to completely evacuate the chamber, and have decided not to get helium for now and to see how a partial normal vacuum will keep the noise down to a reasonable level.
  10. I have tentatively figured out the melted chocolate incident. I must have placed the chocolate on the generator where it melted, then moved it as I began doing the first of the 600V experiments over to a shelf against the wall. and away from the generator, although I don't remember moving it, thinking it had always been on the shelf. I have thought this as a possibility as the generator's power switch is on the secondary of the standard 60hz transformer, leaving the primary energized if the unit is plugged in, and does so to keep the temperature inside the unit warm, and therefore the top of the case where the chocolate container would have been. This is done for more stability when switched on. Sorry, I should have come to this conclusion and posted sooner.
  11. today I set the value for the bias to -30V to give approx 35ma idle current per tube. The plate and screen grids of each tube are tied together at approx +350V, as the 5KV supply is not hooked up yet. The cathodes are all directly hooked to ground. No AC signal is as of yet been applied to the grids.
  12. sorry, I misspelled wonderous.
  13. An excellent lecture on perovskite materials is on youtube "The Woderous World of Perovskites - with Mike Glazer". From 2017, covering it's history and up to the current research.
  14. the pyro electric effect of perovskite material is used to sense temperature change, and does emit a charge when stimulated, but seems very unlikely that the change in heat was sufficient to make any significant charge sufficient for arcing, and the heat was almost entirely applied to the tab itself, taking care not to heat the piezo and especially the poly washer any more than necessary, which melts easily being made from common polyethelene. I did make a few attempts to stimulate charge through heating and resoldering some of the tabs, but found no charge, and noticed one of the poly washers was getting slightly melted with the repeated heating. I planned on only having to heat them once, and did not expect to be sidetracked with this issue, so will return to it next month when I will build another stack specifically to test for excessive pyro electric charge, and proceed with getting the planned tests in order.
  15. I failed to mention the method of my soldering, which is "ball soldering" and I leave the pencil on about a half second longer than needed and add the little extra solder, then flick the pencil away while the tip scrapes off the connection. In this way a roundish blob is pulled off the connection and then has enough heat to snap back from surface tension, leaving a smooth shiny round surface. Could the act of the quick and sliding removal trigger charge? Or the rapid drop in temperature, or a change in shape of the drop as it congeals and forms a minimum surface? Both sparks occurred exactly as I pulled off the pencil tip. Since this oddity took place twice in quick succession, it seems worthy of checking out further, as the sparks seemed substantial enough to have knocked me out of my chair, but mostly from the unexpectedness of the situation. I will go ahead and hook up a fet voltmeter to the suspected tabs and see if I can replicate the sparking by resoldering the tabs once more.
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