Electrical Madness | Home

It was some bored day in January. We really should have been revising but you know how you try an put it off. I noramlly clean my room or alphabetise my CD collection. Cheesy decided to blow something up. The thing he chose was an old transformer. Not the Optimus Prime - robots in disguise sort mind you, an electrical transformer. This seemed like quite a cool idea so Roo watched and took photos.

In the interests of accuracy and lets face it, truth, I will attempt to reconstruct a more accurate picture of what actually went on that morning.

The details are hazy but the construction involved a transformer, a capacitor and required a soldering iron. You can imagine.

First off, the object of the excercise was not to blow up not the transformer, but the capacitor - an old electrolytic to be precise. For those of you that don't know, electrolytic capacitors are polar - they like to be wired for DC current in a particular direction. They do not like to be connected to the mains. Nossiree bob.

The idea was to ramp up the voltage using the transformer from an old DC power supply, in the hope of upsetting the capacitor even more.
Circuit diagram:

  Mains     Transf.  Capacitor
  _       ___ ||<     |
 / \ 240v    >||<    ===
    \_/   ___>||<    ---
Given that the transformer output about 20vac when wired 'forwards' it was calculated that approximately 4.8kvac would be present on the output winding in the reversed configuration. This was deemed seriously excessive for frying most capacitors.

Please also note the dressing gown. This is a vital aid to both creative and electrical thinking. Oh yes. It had nothing to do with the fact that I hadn't bothered to dress. Oh no.

Once the device was finished we set up in the living room. The device was placed on the patio, with us inside. The patio doors were shut, but enough room was allowed for an extension cable to reach the transformer outside. All that was left to do was plug it in....
What Roo doesn't mention is that after several minutes of carefully planning the best way of avoiding accidents and then rearranging furniture and mains cables, I gingerly reached over to plug the thing in, and...
...the cable didn't reach! Witness 2 more minutes of rearraning.
Cheesy bravely plugged it in and...

nothing. The fuse in the extension cable was dead.

As we had no fuses (and secretly didn't want the fuse to go once this marvellous contraption was plugged in anyway) an executive decision was made to replace the fuse with tinfoil. This may seem scary. Shit, it is scary. Kids never ever plug strange electrical things which are likely to draw huge current into the mains with only a huge wad of foil for a fuse. Please.
Actually it wasn't all that bad. As you can see in photo 2 the extension cable was plugged into a 4-bar which was of course properly fused at 13amps where it plugged into the wall.
In the design phase it was deicded that the easiest way of ensuring a reliable mains connection would be to solder the (reversed) transformer to the mains pins on its original case. You can just about make out the old voltage selection gubbins in the picture.

Wrt. the fuse, what you dont see pictured here (I thought we took one *shrug*) is the plug fused with foil plugged uncovered into the 4-way. This was far more dangerous than the foil, especially given the upstream 13 amp fuse and the over zealous trip switch. To be fair, since the original fuse was a 3 amp I assume it just blew outright, rather than being already dead.

I'd just like to re-iterate Roo's safetey warning. Don't try anything you see here at home! It would just be too bad if you fried your brains because you tried this stuff yourself. Truly, my heart would cry out for you. 'FUCKWIT!' it would cry.

The plug was re-plugged and we finally saw... magic smoke. This lasted approx 4 seconds before the fuse box in the hall had enough and tripped. This was no a big suprise. We've had Quake-Fests where this has happened before.
Well, yes and no... I left the device plugged in, but turned off at the wall. After a short countdown the switch was thrown. There was a spark from the transformer (sadly missed on camera) and about four seconds of smoke, again from the transformer. These events were accompanied by a cry of 'Bastards!' from somewhere above.

Throughout the experiment the capacitor remained strangely unaffected. This was a wholly unexpected result and while the spark and smoke were pleasing, they were not as satisfying as an exploding cap would have been. I assume the spark was what blew the trip and the smoke 'mereley' the delayed result of some serious overheating. I could well be wrong.

It is assumed that the mysterious cry identified during the course of the experiment was in fact the crashing call of the lesser spotted Windows luser. The creature in question was most likely in the process of rearranging its ritualistic pictures known as 'Clip Art' when it was startled by the flash causing it to have to start all over again.

After the experiment the apparatus was re-examined. It was discovered that the smoke had been caused by the melting of the mains winding (the original secondary, before all the fun started). The piddly little copper wire had overheated, melting both its coating and the overall plastic wrapping of the coil. It had even vapourised in one place, depositing a patina of copper on the plastic of the case. There were to be pictures of the damage but the transformer is missing, presumed tidied by Gavin.

This severe meltdown was put down to either the effective short on the output winding or the (presumably incorrect) impedance of the mains winding. This was until the underside of the transformer was examined. There, for all to see lay the evidence of our fatal flaw. The transformer had been sat across the pins plugged directly into the mains! Pretty welded spots were evident on the metal base of the transformer, a testament to the ridiculous currents being passed through it.. Perhaps this caused the meltdown or perhaps it would have happened anyway. I'm not entirely sure, but I do know one thing:

There is another transformer under my bed, so there's a good chance we'll be finding out at some point.

Last edited 01-04-99