Anomalous result in a CFL resonant power circuit

Alternative energy sources
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The usual. As I have two large solar PV systems here, and my lab assistant just put one in, and others are interested in things like this, here's where that stuff goes. This is mostly for things that work now, not "gee someday a fusor will do this" -- we know that, but it's not someday yet.
The hope is to save anyone embarking on this sort of thing a lot of wasted time and money, as at least I have been off the grid since 1980 and have had a lot of practice (and made mistakes you won't have to).

Anomalous result in a CFL resonant power circuit

Postby Alex Funk » Wed Nov 09, 2011 2:40 pm

http://www.youtube.com/user/lasersaber# ... oEXCweMxhk

Note that at 3:00 the circuit re-energizes (lights the bulb) at the re-introduction of an electrolytic capacitor, when no battery is attached.

Fraud, or something more significant? He has not published his schematic yet (or at least I have not found it yet) because he has not been able to replicate this result.
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Re: Anomalous result in a CFL resonant power circuit

Postby chrismb » Wed Nov 09, 2011 3:02 pm

Sorry to be a debunker, but this is not surprising. Fluorescent lights don't need much current, they just need volts. The circuit winds up the volts real high (probably higher than the bulb is designed to run at, and prob higher than the cap ratings too!) With that many electrolytics all charged up I am not wholly surprised it keeps on running for that long. I took the trouble to watch it out and the buld seems to be dimming after 30 seconds or so. He was careful to select the capacitor that he took out first as the one he put in first (has the most charge), then put them back in reverse order. Did you notice that?

There may also be a reasonable amount of magnetic energy in the inductor, in addition to the caps. The inductor is slowing the discharge of the caps to a teeny trickle of HV.

(PS... The reason the super caps don't work? Simply because they are more sensitive to being over-voltage!... He has probably already blown them up internally.)
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Re: Anomalous result in a CFL resonant power circuit

Postby Doug Coulter » Wed Nov 09, 2011 3:07 pm

So? He's running a 5w ccfl at about 1/2 watt, given the lighting I saw, which a few electrolytics, removed while still charged, can do for quite a long time - especially that many of them. No surprise the light lit back up when he plugged them back in still charged. Didn't watch the whole thing...super caps have tons of series resistance so won't do high peak currents, like an elastic flyback circuit to make HV off low volts requires, no surprise there either.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Anomalous result in a CFL resonant power circuit

Postby Alex Funk » Wed Nov 09, 2011 11:40 pm

chrismb wrote:

He was careful to select the capacitor that he took out first as the one he put in first


I did wonder why he was about to put one back in and then put it down and chose another one. On reviewing, I noticed it was the first one he took out. Good call!

Various posts from forums indicated that other practitioners had not been able to achieve more than about 5 seconds of illumination from a CFL without battery assist. Resonance or not, I expect way less CFL duration from electrolytic capacitors than the dwell time of your average LED pilot lamp when you pull the plug on a power supply (which admittedly has a bleed resistor), normally 1-5 seconds. Just my 2 cents.
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Re: Anomalous result in a CFL resonant power circuit

Postby Doug Coulter » Thu Nov 10, 2011 9:49 am

Most CCFL power supplies are quite inefficient - makes them cheaper, and when you're putting out real power yet still saving plenty over an incandescent, no sweat - the usual Generous Electric deal. Most of that power is wasted in ballasting the difference between strike and maintain voltage, and many off the shelf models just use a small series cap, the peak currents from which create I2R loss in other stuff in there.

Here the guy used a crazy big inductor for that - much more efficient, and to my eye, ran the lamp at bare minimum power. In a sense you could say that was resonant but it would be a very loose use of that word. Further I'd bet that he used a circuit that would produce constant current into the lamp over a wide range of input voltage. Then he puts in an enourmous bank (for this) of electrolytics (which he carefully doesn't mention the values of). There's your battery when there's no battery. And he claimed that those 18v worth of batteries weren't...yeah, right.

Going over to digikey, we can find 47,000 uF caps @ 6v the size he had, and how many did he have, 10 or so? Half a farad or thereabouts? (you can overvolt common new electrolytics for quite awhile before the failure rate goes up - what happens is eventually the capacity goes down as they re-form). Obviously he was not measuring the huge current during charging these - not a scope in sight. So, going to the old .5CV2 equation... we have .5*.5F * (being generous) 102 = 25 watt/seconds, or enough to run half a watt for 50 seconds - does it all add up now? If his 9v batteries were good, it'd have been 18 squared...a lot more joules.

Like Rossi's fusion, it's easy to fool people who *think* they are smart, till some boring guy comes along with a calculator...and knowledge of how to use it.

Remember in a thing with an LED, the caps are as small as they can be and the thing still work - capacity isn't cheap or small, and that turning off input power doesn't remove the device load other than the led from the caps, which is why they only stay up a second or so...
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