Procrastinatus

Why talk about it now?

Archive for July, 2008

Dual 2n3055 Flyback Driver

Posted by aonomus on July 20, 2008

So for my first real flyback driver, I built a dual 2n3055 transistor based flyback driver. The gist of it is that while one 2n3055 overheats very quickly, 2 paralleled 2n3055s will be able to split the current load and avoid overheating too rapidly.

I used a long terminal strip to arrange the resistor components, had a fan on the heatsink to cool it down, and used some alligator clip leads to make a chicken stick for the HV side.

Once I had the driver setup I was able to push up to 30V at 3-4A into the driver with only moderate heating of the transistors. Short hot arcs or long-duration arcs cause the transistors to heat up significantly, and a short cooldown time is required for the heat to transfer over to the heatsink where it is quickly dissipated. After I figured this out, I was able to push up to 5A (max capabilities of my PSU), where arc over of the flyback pins started to occur, melting charring one of the alligator clip insulating boots slightly.

After I solved the arcover problem with some extra plastic insulation, the fun began, I strung together 3, then 4 disposable camera flash tubes. When you connect a flash tube directly to the flyback, it has a dim arc inside the tube, but I suppose the slight capacitance of the wiring creates a much brighter flash whenever a momentary arc forms.

Another interesting discovery I made was that at these voltages, everything behaves differently, particularly electrostatic attraction/repulsion, and magnetism. At HV, tissue paper flies away from the negative lead, and camera flash tubes roll away, you’ll have noticed that I had to tape down the tubes earlier because they continued to roll away. Whenever an arc formed, the HV leads would jump slightly as the arc formed too, I can only imagine that this would be even more near a magnet.

The schematic (source: wiki.4hv.org) of the driver is fairly straightforward, the only issue I had was remembering that the feedback coil had to be reversed. The basis for this circuit is that there is always current flowing into the base of the 2n3055, and that when the primary coil energizes, the magnetic field of the transformer core cancels out the voltage in the feedback coil, turning off the transistor, which allows the feedback coil to come back up to voltage, and the cycle repeats. A similar driver exists where 2 2n3055’s are set in a push-pull configuration for full-wave AC input, which is my next step, followed by a Mazilli ZVS driver with IRFP250’s. Until then, this driver should be useful, right up until I burn out the secondary that is 😀

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Posted in High Voltage | 4 Comments »

Spectrum Analyzer Update – 60 Hz Band Test

Posted by aonomus on July 19, 2008

Well, I received parts today from Digikey and put together my first bandpass filter at 60 Hz, the video outlines just about everything, starting with a brief explanation, test with a song, then test with a frequency generator.

Also, the schematic is mostly done however I’m holding off on releasing it until I find a better way to give this a pre-amp. The LM358 used for a bandpass filter seems to require a heck of input voltage in order to give any output, and likely I would need to preamp each band individually, thus the schematic would get more complicated.

Ok, enough with the wall of text, video time.

Posted in Audio Spectrum Analyzer, Electronics, Projects | Tagged: | Leave a Comment »

Um. What?

Posted by aonomus on July 18, 2008

So I received my *big* digikey order today and I began the nerd ritual of unboxing. First thing that catches my eye is a label that reads “RES 1.2K OHM 1/4W 5% CARBON FILM” only to be stapled to a bag of plastic connectors (which I didn’t order either). Oh well, only part out of the order, but for a hand picked thing I’m surprised there wasn’t any check for mistakes before packaging…. too bad I didn’t receive a pile of IGBT bricks or something better.

So a quick 1-800 call and I manage to find out that it must have been in the same row, maybe the same bin and digikey hand-picks all their orders anyways, so for a low error rate, just my luck 😀 I might have to return these ones, which would suck due to S&H and customs. I didn’t even get the metal pins so these connectors are kinda useless too….

Update: I got charged $0.61 for the resistors, and zero for the S&H cause they made a mistake and likely will ship Monday. Good luck for my first Digikey order…. now if that catalog will arrive I can collapse my bookshelf.

Posted in Electronics, How Not to Do It | Tagged: | 1 Comment »

The Khadr Situation

Posted by aonomus on July 16, 2008

Well, I’m sure this post is going to garner alot of flak. Thank goodness for the ability to deny racist comments.

For those of you that don’t know, Omar Khadr is a Canadian who was raised by his parents to fight Westerners, and several years ago when he was 15, he allegedly threw a grenade that killed one soldier and blinded another. He is now 21, in gitmo (Guantanamo bay) undergoing various forms of torture such as sleep deprivation and psychological abuse.

Now among the various troubling points I’d like to make one comment first and foremost. I would like to criticize many of the news and media companies covering the story, CBC in particular, as one of their more recent articles regarding Khadr’s mother voicing her thoughts brought hatred in the form of comments on this CBC news article.

My first thought is that the ‘prairie dwelling rednecks’ (yet another divisive hate charged term used by commenters) really should be informed before they make baseless unfounded comments. The CBC allows borderline hate speech comments on this article because its sensationalist news coverage, it might as well be FOX news. Not once have I seen any news coverage regarding the deceased soldier’s family, nor their opinion. For their narrow minded ratings driven, American style news, I have to give them a F- – (ever so blatantly taken from Futurama).

My next criticism is towards the Canadian government. Quite frankly the parties at fault here are the mother and father who either failed to do the right thing, or intentionally did the wrong thing (as in the case of the father, who influenced and raised his son to hate western society). At the age of 15, the UN would consider him a child soldier, yet he was taken to gitmo and was held there for 6 years. The Canadian inaction on something that shouldn’t be happening is likely not due to the majority of people, but likely that Canada is becoming America’s pet.

Canada has never been a major target for any terrorist acts because, suprise suprise, we don’t piss other countries off. We don’t invade under pretext of terrorism, etc etc ad nauseum, or at least we didn’t before. I’m afraid myself now that because we’re becoming more Americanized, we become more of a target.

Canada is an ally of America, and because he was/is a Canadian citizen, that makes his act of tossing a ‘nade and killing someone, treason in effect. A Canadian killing an American probably isn’t all too uncommon in the greater realm of things (think: Canadian druggie visits Vegas and gets in a fight), but because of his race, he gets treated much differently. Many of the comments are so hateful and narrowminded, yet if a white, black, asian, or purple green dinosaur Canadian murdered an American, they would not be screaming for their parents to be deported, sending an already tortured kid to places where he is likely to be killed because of the very same narrow minded view. The hypocritical view of Canadians makes me sad in the fact that we have been brainwashed by American views to hate certain races.

And last of all, my actual opinion on the entire crapstorm that this has become. First off, all of the above is an opinion, but it isn’t mine, it is the opinion of any reasonable Canadian seeing all the hate, which simply shouldn’t happen. My actual opinion is that while he should stand trial in a Canadian court of law for treason against Canada, he should not be allowed to remain if he isn’t allowed to rehabilitate here. Taking a then-15 year old (who mentally is probably the same age now due to isolation) and imprisoning him for life is worse than sending him back to his own country after the war is over.

While the Taliban are illegal combatants, I don’t think that a kid brainwashed to hate westerners should be treated as an adult combatant. It would also be stupidly hypocritical for us to take away the same rights that terrorists threaten. I remember, flipping across the movie network channels seeing a scene of a white gunman holding a head to a middle eastern young adult because he suspected him of being a terrorist. At the end of the movie he said to the gunman ‘look in the mirror, who is the terrorist’ as the gunman stood over a beaten kid tied up to a chair. I can’t remember the name of the movie, but it does sound eerily true by the end of it. While he could have done something bad, taking away his rights and torturing him is no better than what he did, and only reinforces the view that the Middle East holds of westerners.

Posted in Politics, Rant | 1 Comment »

Audio Amplifier and UPS Scrounging

Posted by aonomus on July 13, 2008

Well here is a two parter for my readers, first off I came across a old audio amplifier and a pair of UPS’s whose batteries were dead (inverters were fine but batteries were worth 90% of original cost!), so I pulled out the old soldering iron and went at it.

I have fewer pictures this time, but the end result of the amplifier was a tray of capacitors and some higher power resistors plus a few other bits.

As for the UPS’s, they were APC backUPS 350 and 500 VA models, the power bar/brick model from a few years back. Both of them had failed batteries and unfortunately due to the way the economy works, like inkjet printers, refills and supplies cost more than a new one. I originally bought these on special, so the batteries would cost more than the UPS. The end result was a pile of IRF640 and IRFZ48 mosfets, some caps and a few transformers as well as the dead batteries (which I did try to recondition before I wrote these off).

And another quick update, some parts for my spectrum analyzer arrived, a large pile of LED’s, some trim pots, and connectors to use. The major shipment with digikey won’t ship until the most important (and therefore the only backordered part) LM3915’s arrive to their distribution warehouse. The shipment contains a ton of other parts such as 2n3055 transistors (and higher power counterparts) for a simple flyback driver, some IRFP450 mosfets for a ZVS flyback driver, and other goodies.

Posted in Audio Spectrum Analyzer, Electronics, Scrounging | Leave a Comment »