Kapanadze Cousin - DALLY FREE ENERGY

[TinselKoala]

Nick, that last scopeshot shows, I calculate, almost exactly 500 kHz. You have almost exactly 8 full cycles in the middle 8 divisions, at 2 microseconds per division, right? 8 divisions at 2 us/div is 16 us, so you have 8 cycles per 16 microseconds.

So the math is 8 / 0.000016 = 500000

If you could show your workings how you got to the "2 MHz" figure, we might be able to zero in on where your misunderstanding is.

[TinselKoala]

Another way to look at it is this:

If you had one full cycle in one microsecond (one millionth of a second) you'd obviously have a million cycles in one second. One MHz, right? But you have one full cycle in _two_ microseconds (one division) , so you will only have half a million cycles in one second. 500,000 cycles per second, or 500 kHz.

[NickZ]

  Ok, well thanks for that.  I guess there may be something wrong with that reading, and I don't mean the math.
I thought that it was reading 5Mhz, not 2Mhz, or 500Khz, but it is what it is. In any case, the frequency should be much higher than that 500Khz.
I'll try it again with the 50ohm resistor and using the square wave signal.
I don't understand why it might be showing such a low reading. I'll see what I can do.
  Thanks again.
 

[Dog-One]

Guys is anyone here that bothered to measure the exact length of grenade with 48T first layer at 5cm diam. tube? I know that i take you way back but really have you tried to calculate it? I started to wind a new grenade and i don't know what is wrong. I find out that total length is 29m. To reach 37m i calculate that i need about 68T first layer. Is that true?

First off, what kind of wire are you using?

I'm using standard stranded electrical wire 10 AWG.  48 - 24 -12 gives me exactly 34.45 meters measured with a laser range finder accurate to +/- 5mm.

I'm not able to get 37.5 meters with the tube size I have available or the thickness of the insulation.  My windings are very tight, hot glued and taped as I went along to be sure the coil didn't come unwound.

Personally, I think larger is probably going to be better because the frequencies you will have to deal with will be lower, but regardless it appears any coil can be tuned to operate as intended, you just won't be able to use any one else's specifications.

The reason I know the exact length of my coil is because I wound it, unwound it, measured the wire and wound back exactly as the first time using tic marks for alignment.  In a painful tedious process, but if you want to be sure of your values, it's the only way I know to do it.

[TinselKoala]

  Ok, well thanks for that.  I guess there may be something wrong with that reading, and I don't mean the math.
I thought that it was reading 5Mhz, not 2Mhz, or 500Khz, but it is what it is. In any case, the frequency should be much higher than that 500Khz.
I'll try it again with the 50ohm resistor and using the square wave signal.
I don't understand why it might be showing such a low reading. I'll see what I can do.
  Thanks again.

It's possible that you are picking up and seeing a subharmonic; there can sometimes be several "resonance" peaks, but the true 1/4-wave resonance will have the greatest amplitude of the possible harmonics.

Well, at least you don't have to worry about "Aliasing" like you do with a Digital scope. A solid signal like that on the Analog screen is "wysiwyg", it is showing the actual frequency of the signal and not some digital artefact caused by undersampling a higher frequency. 


Again, if you can describe the process you used to work out your answer, we can find where your math is going wrong and correct it.

If you follow my procedure for calculating the frequency from the scopetrace, it's really not that hard. I notice you have been putting a "bottom valley" on the graticule line; that's OK it's just a little weird, usually we would use a top peak or a zero crossing, but what you are doing works OK too, for a nice sinewave like you are showing.

So we use the middle eight horizontal divisions, to get a nice average that reduces effects of edge distortion in the CRT. So you take your Horizontal Scale setting and multiply that by eight, and that gives you the time covered by those eight horizontal divisions.

Then you count the full cycles that appear within that timespan, estimating if you have partial cycles. This is easiest (for me) if you put a peak right on the beginning of the eight divisions, but putting a valley or a zero-crossing there is fine if that is your preference. Then you just count the peaks (or valleys etc.) to get the number of full cycles from there over to the end of the eight divisions. This gives you the number of full cycles that happen in that timespan.

Then to convert to Hz you simply divide the number of cycles by the timespan, so in this case you have 8 full cycles, divided by 16 microseconds. 8/0.000016  = 500,000 cycles per second = 500 kHz. It is harder to describe in words than it is to actually do it.

Here's an old video that I made, illustrating the process. You can skip the "calibration" part in the video since you don't have a precise reference signal to calibrate to; your scope should be close enough without doing that part.

http://www.youtube.com/watch?v=teXXF0a_WoI