When I was in computer repair class in high school, I tried to measure the voltage of a PC power supply but accidentally left my cheap meter set for amps. The insulation melted right off the meter wires and I still have the scar where the wire was touching my arm. I now use a CAT III rated meter and switch out of amps once I finish the measurement.
In that class, film cans are used to store spare screws. One time, I set the can too close to the edge of the table. That combined with the fact that the table was right below breast level made for a very hilarious moment when I suddenly turned around to answer another student's question. A few dozen screws rolled across the floor and caught everyone's attention.
Then there's the time when I was working on a CPU cooler using R134a as the working fluid. I was disconnecting the gauges and a little R134a hit me in the nipple. Hurts a lot.
Relating to that, I had to repair my home A/C about 2 years ago. I was (once again) disconnecting the gauges and that time, I was sitting on the ground next to the unit and the service connections were also near the ground. Let me just say that a little ES-22a hitting that other sensitive spot doesn't feel good either!
In that class, film cans are used to store spare screws. One time, I set the can too close to the edge of the table. That combined with the fact that the table was right below breast level made for a very hilarious moment when I suddenly turned around to answer another student's question. A few dozen screws rolled across the floor and caught everyone's attention.
Then there's the time when I was working on a CPU cooler using R134a as the working fluid. I was disconnecting the gauges and a little R134a hit me in the nipple. Hurts a lot.
Relating to that, I had to repair my home A/C about 2 years ago. I was (once again) disconnecting the gauges and that time, I was sitting on the ground next to the unit and the service connections were also near the ground. Let me just say that a little ES-22a hitting that other sensitive spot doesn't feel good either!
Not really stoopid but fun! Connecting a crystal earphone to a
mains plug and plugging it in at school
Somewhat stoopid,
connecting some lower voltage high u caps with polarity reversed
to the +- 70v psu of one of the new amps we were developing some
years ago. Switching on and then going for a coffee in the canteen.
Coming back and not being able to find the amp due to the smoke
My worst diy project was a total rebuild/rewire of a 24 channel stage
mixer including converting it to multicable. The time spent could have
easily payed for a good used one
Oh did I forget the coax bandpass filter for the local turkish radio station?
A slight miscalc made it into a quite a good harmonic enhancer and schiphol
airport did not really like me Some 25 watts of erp bouncing around
on not exactly the intended frequency coming out of quad stacked dipoles.
mains plug and plugging it in at school
Somewhat stoopid,connecting some lower voltage high u caps with polarity reversed
to the +- 70v psu of one of the new amps we were developing some
years ago. Switching on and then going for a coffee in the canteen.
Coming back and not being able to find the amp due to the smoke
My worst diy project was a total rebuild/rewire of a 24 channel stage
mixer including converting it to multicable. The time spent could have
easily payed for a good used one
Oh did I forget the coax bandpass filter for the local turkish radio station?
A slight miscalc made it into a quite a good harmonic enhancer and schiphol
airport did not really like me
Some 25 watts of erp bouncing aroundon not exactly the intended frequency coming out of quad stacked dipoles.
My worst DIY project
Undoubtedly the worst DIY project I ever concocted was the hot air balloon I made as a teenager. In this was aided and abetted by my very mischievous brother-in-law. The balloon was quite successful and sailed high into the air above the Johannesburg suburb where we lived. But then it caught fire and summarily plumetted to earth as an incendiary bomb. As luck would have it, it fell onto the property of the local Dutch Reformed Church minister - a po-faced disapproving gent if ever there was - and went crashing through the roof of his wooden chicken coop, which began burning merrily. The good reverend became more po-faced than ever after this incident, but fortunately he never discovered how or why his chicken coop suddenly burst into flames.
This was my last aviation project. I decided to stick to electronics after this.
Undoubtedly the worst DIY project I ever concocted was the hot air balloon I made as a teenager. In this was aided and abetted by my very mischievous brother-in-law. The balloon was quite successful and sailed high into the air above the Johannesburg suburb where we lived. But then it caught fire and summarily plumetted to earth as an incendiary bomb. As luck would have it, it fell onto the property of the local Dutch Reformed Church minister - a po-faced disapproving gent if ever there was - and went crashing through the roof of his wooden chicken coop, which began burning merrily. The good reverend became more po-faced than ever after this incident, but fortunately he never discovered how or why his chicken coop suddenly burst into flames.
This was my last aviation project. I decided to stick to electronics after this.
I tried to make a speed controller for a 3HP Chief 29 printing press with a Radio Shack "30A 400V" triac. Talk about tail wagging dog. Needless to say throwing the breaker vaporized the triac and threw the little heatsink it was in across the room. I guess they didn't mean 30A and 220V at the same time.
Very dramatic.
Very dramatic.
Another classic project of mine that didn't quite hit the spot was the PCB Etching Centre I made in the early 1980's during the university holidays. Encouraged by a visit to a real PCB plant in Johannesburg, I decided to approximate the processes at home. I got a great big board about 1.5m x 1m which I set on castors, and on this board I mounted a massive 1/4 HP mains motor, complete with earth leakage relay and circuit breaker. The motor was fitted to drive a water pump of the kind one buys at a hardware store to attach to an electric drill. This was to circulate the ferric chloride which would be sprayed under pressure onto the PCB in an etching tank. I made the tank out of chipboard, with perspex front and back panels and perspex lid. I coated the inside of the chipboard with silicone goo, hopefully assumed resistant to Ferric chloride. Also in the etching tank was an electric kettle element controlled by a thermostat. I sprayed the element with hi-heat engine enamel, also assumed resistant to ferric chloride. All the plastic pipes and cables were lovingly and neatly routed around the board in straight lines and clamped down like I'd learned to do as an apprentice.
I tested my efforts using water and it all worked really well. Then the time came to etch a pcb and I filled the system with ferric chloride. This, too, worked well. For about three minutes. Then I noticed bits of some strange black stuff were blocking up my spray jets in the etching tank. This was little bits of the rubber impeller from the pump, which was slowly dissolving in the ferric. At about the same time, the ferric ate a hole in the thermostat and another in the electric element, which shorted out and tripped its circuit breaker. Encouraged by this, the ferric began to leak from the tank at a multitude of different places. Meanwhile, pump was having a hard time pumping the fluid past the obstructions caused by bits of itself and inevitably a hose burst and ferric began to spray from the burst pipe over everything and everyone in the vicinity. With much of its impeller dissolved the pump began to vibrate severely and tore itself free of its rubber mountings. It spun around on the motor shaft - the motor of course didn't feel anything - like a catherine wheel, spraying ferric on the walls, the floor, and even on the roof of the garage. At this point, as the last of the ferric gushed out of the etching tank I observed that despite all the carnage, my PCB had at least been etched nicely.
All that remained was to clean up the mess, which took three days. I derived some revenge from using 'elephant tools' to smash the Etching Centre into pieces small enough to fit in the trash bin.
I have not made a PCB at home since. My mother forbade any further such endeavours after this incident, and around the time I got married, she recommended to my wife that this prohibition be extended for my lifetime.
I tested my efforts using water and it all worked really well. Then the time came to etch a pcb and I filled the system with ferric chloride. This, too, worked well. For about three minutes. Then I noticed bits of some strange black stuff were blocking up my spray jets in the etching tank. This was little bits of the rubber impeller from the pump, which was slowly dissolving in the ferric. At about the same time, the ferric ate a hole in the thermostat and another in the electric element, which shorted out and tripped its circuit breaker. Encouraged by this, the ferric began to leak from the tank at a multitude of different places. Meanwhile, pump was having a hard time pumping the fluid past the obstructions caused by bits of itself and inevitably a hose burst and ferric began to spray from the burst pipe over everything and everyone in the vicinity. With much of its impeller dissolved the pump began to vibrate severely and tore itself free of its rubber mountings. It spun around on the motor shaft - the motor of course didn't feel anything - like a catherine wheel, spraying ferric on the walls, the floor, and even on the roof of the garage. At this point, as the last of the ferric gushed out of the etching tank I observed that despite all the carnage, my PCB had at least been etched nicely.
All that remained was to clean up the mess, which took three days. I derived some revenge from using 'elephant tools' to smash the Etching Centre into pieces small enough to fit in the trash bin.
I have not made a PCB at home since. My mother forbade any further such endeavours after this incident, and around the time I got married, she recommended to my wife that this prohibition be extended for my lifetime.
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