Hacker News new | past | comments | ask | show | jobs | submit login

I understand he got permission and everything was checked out by actual RF eggheads, but damn. I won't even change a HV run capacitor unless i'm wearing crocs, standing on cement, and wearing the rubber oven mitts. And even then, I keep one hand behind my back. Because there have been accidents, and they hurt (the pool pump run cap fails approximately annually in this climate and if I paid someone to change it every time, I'd be a lot poorer).

That said, the food demodulating the signal into audible noise is badass.




Cement is surpisingly conductive. I have a thick rubber mat I stand on when doing high voltage (CRT, etc) repair work, and even then I have a full set of rated protective gear, and precautions (one hand in pocket, etc)


Just short the terminals with a screwdriver before you touch anything else? (Look away in case there's an brief arc flash)


Oh man, that reminds me of a mistake I made a few years back.

I had opened up a motor controller to fix it, and I knew to discharge the cap before messing around inside. I applied a screwdriver across the terminals to short it out, and was rewarded with a beautiful long and skinny arc as the screwdriver came into contact. I said out loud, "That was cool", and my coworker sitting behind me said, "What was cool"? I told him that I had just shorted out the cap and the arc looked really cool. So he said, "Can you show me?" I said sure, and plugged the controller in for a few seconds to recharge it, then unplugged it and proceeded to repeat what I had just done.

What I had forgotten was that previously the motor controller had been unplugged overnight. When I touched the screwdriver to the freshly charged capacitor, there was a boom, a three inch fireball, and the end of the screwdriver was completely gone. As I sat there thunderstruck, my coworker said, "You're right. That was pretty cool".


Well, your comment was my deep laugh for the day. excellent story. When I was younger, I saw my father working on a ceiling fan...while it was on. I asked him why he did not flip the breaker first and he said "well, as long as you don't touch both wires at the same time, you'll be fine "

Fast forward a few days later I am at school, and I see in one of the outlets one of the prongs for a power cable had broken off in it. I remembered his advice about not touching both sides and proceeded to try and pull it out using my fingers...you can probably imagine what happened. It grabbed hold of me for a few seconds and a lesson was learned.


In theory, if you were wearing rubber shoes and not touching any other path to ground, you would have been fine.


I think supporting myself by holding the metal of one of those school desks was a factor possibly.


Ideally you’d short a run cap with a suitable resistor, but you’re right, short the cap right after de-energizing the motor circuit before touching it with your hands.


Yeah, I try to bleed it with a long-handle screwdriver for 30 seconds. In fact, the couple times I've managed to zap myself was with residual current even after that, so I can't imagine what the full potential is. It's just a no-fun job.


Does your pool pump run capacitor actually not have a bleed resistor? I thought that was standard issue in start/run capacitors.


Why standing on cement? Wouldn't cement be considered a ground?


Indeed it is. Anybody who's spent time jamming in old basements with bad ground or two-prong plugs has learned this the hard way via a microphone or guitar (myself included). Shoes are essential - not even flip-flops are good enough because even something as simple as walking across a wet lawn will leave enough residual moisture to zap you.




Consider applying for YC's Spring batch! Applications are open till Feb 11.

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: