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Tesla Coil Under load

Discussion in 'General Electronics Discussion' started by pidja105, Apr 9, 2017.

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  1. pidja105


    Oct 16, 2015
    I maked Tesla Coil and connected some NEON bulbs trough WIRES. I noticed with experiments that frequency is changed when load is attached, how to calculate frequency under load?
  2. 73's de Edd

    73's de Edd

    Aug 21, 2015

    Sir pidja105 . . . . .

    That should be QUITE a load, as each neon fires around 60-75 volt threshold and according to how many you had in series. A 4 ft flourescent tube would have been less of a load .
    Plus that level of input should be quite hard on the electrodes.

    If you have a scope you could loooooosely / capacitively just bring a probe up near the unit until you just get a display on the scope in a 5 MV input vertical level sensitivity.
    Then you just count nodes on the screen while adjusting the hoz sweep rate to get in the order of 10 or so nodes across the screen. Then you compute by converting one nodes time duration to frequency.

    If you want to test this out initially, for full familiarization of concept, just hook up the scope to its calibrator square wave output . . .with a norm freq being 1000 cycles.
    Adjust your hoz time base and you will see different numbers of square waves and at one point should have 1 full square wave spread across the 10 calibration graticules from left to right across the scope face.
    You then want to change the hoz setting to 1 decade of a SLOWER sweep speed. That display should have THEN given you right at 10 sq waveforms instead of that previous one.
    NOW you can easily just count your frequency out right on the scope face.
    Concentrating on theFIRST wave forms + going waveform on the extreme left you should find that 10th waveforms negative node just ending at the end of the 10th clibration graticule.
    If you find it ending short of that point your actual frequency is being GREATER than 1000 cycles.
    Or if it has not ended at that end graticuile point . . . . it is lower than 1000 cycles.

    If you look vewy closely, you can further estimate frequency within ~10 cycle increments at 1000~'s.
    ALSO if you just shift to different deccades of settings of the hoz time base you can transition to direct read out of frequency down to 10's of cycles or 100's of cycles or our just mentioned 1000's of cycles or on up to 10K and 100K's of cycles but it is real hairy at seeing the 100K's of cycles . . . less the proper / type of scope.

    ORRRRR if you happen to have a TEK scope with a time base pulse output at the rear with its square wave output.
    You connect that into a frequency counter.
    Then you speed up the hoz time base so that you then have, not MANY, but just LESS that one node, but less the repetiton of a second node being displayed on the screen, you can then read out the frequency on the counter.
    The scope was basically just being a preamp with waveform conditioning for your counter.

    (Same is true on reading out the higher frequencies as was the case above.)

    73's de Edd
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