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Author Topic: Lasersaber strikes again. A joule thief king ?  (Read 412319 times)

scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #315 on: October 27, 2014, 07:42:18 PM »
  Here are the LTSpice files for those who want to run the simulations themselves.


scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #316 on: October 27, 2014, 07:43:16 PM »
  TinselKoala, if you tell me the oscillation frequency of your real circuit I can adjust the LTSpice circuit to match it.

d3x0r

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #317 on: October 27, 2014, 08:34:00 PM »
  Can you post the LTSPice schematics that you got to oscillate ?
I looked, but my system crashed and I lost the VHD that had spice.
I had some falstad sims that worked too...
I'll see what I can dig up


d3x0r

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #318 on: October 27, 2014, 09:28:23 PM »
I'll see what I can dig up
I got nothin.  most simulators require more elasticity in their systems; adding 0.01ohm resistances and 10pF capacitances often helps them behave more like real world things when the thing is a boundary condition...
might be your voltage; might be your idea of top and bottom of the transformer are backward from how it should work.
The LEDs are driven by a low voltage...
might also try setting 'start DC voltage at 0'... without the 1Mohm resistor, having a capacitance beyond the primary coil from power (collector side coil), then a small current can be generated on the other side to pull the npn high, which will allow a higher current through the secondary.  This rising current causes the secondary at the load side to go high, and the base side to go low...


The circuit on http://www.overunity.com/14794/ka4ep-torch-kacher-torch/msg411220/#msg411220  adds some complexity, and the secondary ends up going to ground instead of back to the base... using just the low side of the coil on the base kacher-esque.   I didn't include simulation links there either; sorry.




skycube

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #319 on: October 27, 2014, 11:35:44 PM »
Hi. Try this  LT simulation. It works...

TinselKoala

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #320 on: October 28, 2014, 04:56:53 AM »
In the first part of the second video I posted I am _not using_ the third coil winding at all. The device is wired just exactly as lasersaber's schematic, but with slightly different turns ratio. The LEDs are definitely on. When I connect a single end of the third winding I get brightening of the LEDs. Later I discovered the real effect of the third winding and its proper connections, and that is what is shown in the first video I posted, showing brilliant LEDs running with less than 0.2 V on the capacitor.

The video with the scopeshots (third coil winding connected) shows that there are several superimposed oscillation frequencies happening all at once. I have never seen that slow and stable variation in primary frequency in any JT before.


scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #321 on: October 28, 2014, 10:07:32 AM »
Hi. Try this  LT simulation. It works...

  Skycube,

  I see that you added a parasitic capacitance between the primary and the secondary (C1 in your circuit).
  I thought about doing that, but you were faster.  ;D
  Good work on making it oscillate.

  Anyway, I changed some values in your schematics and managed to get the circuit to oscillate in bursts, which I believe is what the real circuit does (see the attached picture).
  I'm also attaching the LTSpice circuit.


scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #322 on: October 28, 2014, 06:49:29 PM »
  Lasersaber, TinselKoala and others who replicated the experiment: did you measure the input/output energy and did you find overunity ?

  If you didn't measure it but only guesstimated it, do you have any reason to suspect overunity ?

TinselKoala

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #323 on: October 28, 2014, 07:34:38 PM »
No, I have no reason to believe that it is OU. My own interest is merely in very low voltage operation with _useful_ levels of light output. In the sense that these circuits allow the extraction of residual energy in batteries that would normally be discarded as unable to run anything... well, that's "free energy" isn't it? Or rather, it's energy that you paid for when you bought the battery but can't normally use.

By the way, your latest series of scopeshots looks pretty good, very similar to what I showed in the last video above but with higher Q. It's too bad that a DSO or simulated DSO can't also show that much slower variation in burst frequency that shows up on the analog scope as "shrinking and expanding" along the horizontal axis. It would be interesting to see if your sim behaves that way, but I don't know how you'd be able to catch it on the screen.

The idea of coupling the coils with a small capacitor is interesting. I may try that in my systems a bit later on.

scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #324 on: October 29, 2014, 01:51:37 PM »
By the way, your latest series of scopeshots looks pretty good, very similar to what I showed in the last video above but with higher Q. It's too bad that a DSO or simulated DSO can't also show that much slower variation in burst frequency that shows up on the analog scope as "shrinking and expanding" along the horizontal axis. It would be interesting to see if your sim behaves that way, but I don't know how you'd be able to catch it on the screen.

The idea of coupling the coils with a small capacitor is interesting. I may try that in my systems a bit later on.

  You can catch it with the simulator if the simulation duration is long enough. Let's say that the "shrinking and expanding" phenomenon has a period of 1s. Then you simulate your circuit for 1s and you should see the duration between two big consecutive spikes varying.
  But I don't believe that this LTSpice circuit reproduces that phenomenon since there is nothing in it to generate an oscillation with such a long period (around 1s).
 
  If you're interested in simulating that phenomenon, here are some ideas that might explain it (in decreasing order of probability):
1. The transistor's temperature (or maybe the LEDs') varies periodically (with a period of about 1s) which changes the duration between the spikes. So we have here a "thermal oscillator" with a low enough frequency (about 1Hz).
2. The circuit generates two oscillations and their frequencies are close: for example 100Hz and 101Hz. The oscillations create interference between them (or "beatings") with a frequency of 1Hz that you see on the scope.
3. Maybe there is no oscillation with a period of ~1s but there is something wrong with the measurement set-up.

  In my opinion the first explanation is quite plausible, the second one is unlikely and the third one even is more unlikely if the oscilloscope operates correctly.

  Anyway, let me know if you want to do more experiments to find out the cause of the "shrinking and expanding" you see on the scope, maybe I can help.

TinselKoala

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #325 on: October 29, 2014, 02:24:17 PM »
That's a good idea. I can test the component temperature hypothesis easily enough with some "cold spray".

My own DSO, when used at slow timebase settings, is also correspondingly slow to refresh the display, so you don't see anything like the "live" display as shown on the analog scope. But a full scan would show, as you state, "bunches" and "voids" where the slow-period oscillations happen.  Somewhat as below probably, from a different circuit entirely.

scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #326 on: October 29, 2014, 05:11:44 PM »
That's a good idea. I can test the component temperature hypothesis easily enough with some "cold spray".

  Another way to test the "thermal oscillator" hypothesis is to put the transistor (and/or the LEDs) on a big enough heat sink with a good thermal contact (maybe using thermal paste).
  Since the heat sink has a much bigger thermal inertia than the transistor case, the oscillation should disappear.

scifi123

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #327 on: October 29, 2014, 07:35:02 PM »
My own DSO, when used at slow timebase settings, is also correspondingly slow to refresh the display, so you don't see anything like the "live" display as shown on the analog scope.

  Most of the digital scopes have a display refresh rate of 20-60Hz (even the Chinese ones) so you should be able to see it, I think.
  Here are some pointers:

1. Set your timebase to around 3-10 times the duration between spikes. For example, if the spikes have 1ms between them, you can set the timebase to 10ms.
  You can use the analog scope to measure the duration between spikes.

2. Set your sampling period to be 100-1000 times smaller than the timebase. In the example above, the timebase is 10ms, the sampling period should be 10-100us, i.e. the sampling frequency should be 10-100kHz.

3. Set your trigger level to be somewhat smaller then the peak of spikes. If the spikes peak at 5V, a good triggering level would be 4V.

  That should be a good starting point for visualizing the "shrinking and expanding" on a DSO. If your DSO is fast enough, you can decrease the sampling period to be 10000 times smaller than the timebase, i.e. 1us for our example.

  Happy hunting !  ;D

P.S. What is the model of your DSO ? Maybe I can take a quick look at its specs to be more helpful.

TinselKoala

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #328 on: October 29, 2014, 08:13:23 PM »
Thank you for your advice. I am always willing to learn more about the use (and abuse) of oscilloscopes.

The scopeshot above isn't really representative of the circuit we are discussing, it was just the first one I found in my data that showed approximately the same kind of thing. The scope is buried under a pile of stuff at the moment; perhaps I'll  dig it out and do an actual shot of the actual device, later on.

The DSO is an old Link scope made in 1997 that uses the PC (bidirectional parallel port interface!) for display and control. It is the Link DSO-2100M, generously donated by a friend from another forum. I am using the latest available version of the software; I don't really think you are going to be able to tell me anything about this scope that I don't already know, but I'll be interested in your comments regardless. Thanks!

Redoanullah

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #329 on: December 24, 2016, 07:38:48 PM »
Has anyone successfully replicated laser saber's v4.1 ??
  I want to know in detail about it!
I tried the SJR looper with 22# SWG -100 turn as primary, 300# SWG -200 turn as secondary and used 2N2222, 2N3904, MJE3055 transistor.
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I failed.
It doesn't even worked a bit!!
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I think there is something in it's switching that matters!!
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What's that capacitor doing across that schottky diode?