Things that terrify you on the bench.

[bd139]

I find you have to wash with IPA then water then IPA then water again before the sticky goes away. It's annoying but it works.

As for safety encouragement, if you buy a bottle of it from RS, then they send it in a massive box with about 30 pages of hazardous chemical data!

Considering investing in an ultrasonic bath. You can get them for around £30 on Amazon.

[Mr. Scram]

I find you have to wash with IPA then water then IPA then water again before the sticky goes away. It's annoying but it works.

As for safety encouragement, if you buy a bottle of it from RS, then they send it in a massive box with about 30 pages of hazardous chemical data!

Considering investing in an ultrasonic bath. You can get them for around £30 on Amazon.

I think the general advice is to avoid the jewelry cleaner types. I've been eyeing ultrasonic cleaners for a while now too, but doing it right means spending some money.

[paulca]

As for safety encouragement, if you buy a bottle of it from RS, then they send it in a massive box with about 30 pages of hazardous chemical data!

Yep.  I got my flux pen in a box big enough to put a soccer ball in with a print out of the full 50 page safety datasheet and a HUGE hazardous materials sticker on the box.  The solder they sent in a much smaller envelope with it's 20 page safety datasheet.

[Mr. Scram]

That's the problem. If you do that with everything, it loses its punch. Of course, it's good to have the information nearby if something does go awry.

[mikerj]

Simple 240V, I'm scared to death of it, seriously. I would never have made a sparky.

Yep me too, and any HT circuits (e.g. working the back of an old CRT monitor/TV). My worrying tends to lead to sweaty palms as well, not really ideal

[paulca]

Simple 240V, I'm scared to death of it, seriously. I would never have made a sparky.

Yep me too, and any HT circuits (e.g. working the back of an old CRT monitor/TV). My worrying tends to lead to sweaty palms as well, not really ideal

I have been on the receiving end of the tube pull up caps on a CRT monitor.  Not something I want to repeat. Launched me clean across the room and left me as a shaking wreck in the corner, took an hour before I felt normal again.  But I'm still here and a little wiser.

[bd139]

Not sure if I'm higher impedance than the average person or not, but I've had a few zaps and don't find them particularly memorable. Couple of 240v ones made me say "fuck" followed by "mmmm bacon" and I discharged a CRT through myself once and didn't feel anything other than a ting on my toe where it came out.

[tautech]

Best one I ever got was from a valve PSU I built when I was ~13.....zap from the 700V plate terminals on a 5Z4.
45 years later I still remember bouncing off the bed on the other side of the room.
Had a zap or two from a Villiers engine I used to muck with but the 700V is always the one never forgotten.

The things we do  but that's how we learn.

[TheUnnamedNewbie]

Things I don't understand. Mains and tube amp get me thinking twice about every move I make, but if you know what you are dealing with, you also know how to do it safely. But if there is something on the bench and I don't know if it is isolated, or how it is wired up, or what voltages are present, that scares me. Where does the mains go? Are these huge-ass DC caps on the primary side of the DC/DC discharged on power-off?

That and Airsoft/RC batteries. These things don't come with current limit and the good big ones will happily deliver 250+ A on short... I've had to work on airsoft guns a few times and I always make sure to check for shorts 20 times, as well as powering it up with a lab supply (but not firing, since those guns can draw near 100 A peak, 40 A continuous) to check that there are no actives doing strange things.

[Johnboy]

One of my teachers t ITT was a radar tech.  He worked on shipboard radar while live.  He also worked on the big phased array ground radar and said while testing, he watched a deer explode as it passed in front of the array.

...and to think I was looking in the direction of my bench for potential terror. I think this "venison stew surprise" anecdote shocked me more than any of the things I have plugged in around here.

[bd139]

That's an old wives tale passed around. I worked on radar test rigs in a little metal room (stop RF getting in!) many years ago. Even at the business end of things on some massive phased array doodah, you'd get a little warm and that was about it. Most of the reasons for the wives tale existing came from the fact that humans, particularly ones carrying things, get in the way of the signals and don't give a crap about it. That is unless you tell them they're toast if they go near it.

The only time I've seen anything toasted properly was a pigeon became a short on the third rail on the tube in the UK with some loose ground strapping at Stratford. It just smoked a bit and it cleared. Smelled bloody awful.

[paulca]

I'm sure it's an "old engineers tale", but it is told that the microwave oven idea came from radar when they found perfectly cooked seagulls on the radar in Dover.

[Mr. Scram]

I'm sure it's an "old engineers tale", but it is told that the microwave oven idea came from radar when they found perfectly cooked seagulls on the radar in Dover.

The version I know of is engineers finding melted chocolate in their pockets. I'll admit, that version draws less attention than the seagulls.

[bd139]

When I put chocolate in my pocket it melts anyway.

[Mr. Scram]

Wikipedia at least agrees with the candy bar version. The seagull story seems to be an artistic embellishment.

"In 1945, the specific heating effect of a high-power microwave beam was accidentally discovered by Percy Spencer, an American self-taught engineer from Howland, Maine. Employed by Raytheon at the time, he noticed that microwaves from an active radar set he was working on started to melt a candy bar he had in his pocket. The first food deliberately cooked with Spencer's microwave was popcorn, and the second was an egg, which exploded in the face of one of the experimenters.[9][10] To verify his finding, Spencer created a high density electromagnetic field by feeding microwave power from a magnetron into a metal box from which it had no way to escape. When food was placed in the box with the microwave energy, the temperature of the food rose rapidly. On 8 October 1945, Raytheon filed a United States patent application for Spencer's microwave cooking process, and an oven that heated food using microwave energy from a magnetron was soon placed in a Boston restaurant for testing.[11]"

https://en.wikipedia.org/wiki/Microwave_oven#Discovery

[bd139]

Interesting. I worked for them once for a few weeks and had no idea about that 

[GreyWoolfe]

That's an old wives tale passed around. I worked on radar test rigs in a little metal room (stop RF getting in!) many years ago. Even at the business end of things on some massive phased array doodah, you'd get a little warm and that was about it. Most of the reasons for the wives tale existing came from the fact that humans, particularly ones carrying things, get in the way of the signals and don't give a crap about it. That is unless you tell them they're toast if they go near it.

The only time I've seen anything toasted properly was a pigeon became a short on the third rail on the tube in the UK with some loose ground strapping at Stratford. It just smoked a bit and it cleared. Smelled bloody awful.

Not sure why he would tell a tale like that.  He also said that the grass was dead for hundreds of feet in front and the ground was littered with the corpses and bones of animals.  The other thing he said that when working on shipboard radar live, as the antenna rotated, you could hear a hum from the superstructure as the antenna passed it.  I would like to think it wasn't all 

[Mr. Scram]

When I put chocolate in my pocket it melts anyway.

Apparently it was a peanut cluster bar, which melts at a higher temperature and of which Spencer was a fan. If he liked pure chocolate, we may not have had a disappointing way of reheating sad leftovers.

[paulca]

Not sure why he would tell a tale like that.  He also said that the grass was dead for hundreds of feet in front and the ground was littered with the corpses and bones of animals.  The other thing he said that when working on shipboard radar live, as the antenna rotated, you could hear a hum from the superstructure as the antenna passed it.  I would like to think it wasn't all 

I know that when I try and use my phone outside of work, which is about 1000 yards from the Belfast City airport radar it cuts out with the same regularity that the radar rotates.  If I walk around the other side of the building it's fine.  I expect anything that breaks the line of sight to the radar would help.

[Mr. Scram]

Not sure why he would tell a tale like that.  He also said that the grass was dead for hundreds of feet in front and the ground was littered with the corpses and bones of animals.  The other thing he said that when working on shipboard radar live, as the antenna rotated, you could hear a hum from the superstructure as the antenna passed it.  I would like to think it wasn't all 

I don't know why someone would tell spectacular stories about death rays and violence, which also happen to be nearly impossible to verify. 

[BrianHG]

This 10k$ Mitsubishi AM3501R 35 inch multiscan computer monitor.  After paying half price for it used at the time, I had to service it.  And a few mods, after stretching it's horizontal scan rate to 45Khz and RGB drive amp change, and refocusing a few times, I once got the shock of my life from it when my hand slipped doing a live adjustment in the back.

Even the powerup cycle, that 450watt switching would wine up like a rapid electric camera flash charging, but much deeper and louder scared a few of my friends until you got used to it.
However, being the only one at home with a 1024x768 (after mods) progressive scan 35 inch screen with perfect RGB convergence from corner to corner in 1994, with a home made de-intelacer for TV & DVDs lateron the PC in progressive scan as well, you couldn't get better picture at the time.

[bd139]

Not sure why he would tell a tale like that.  He also said that the grass was dead for hundreds of feet in front and the ground was littered with the corpses and bones of animals.  The other thing he said that when working on shipboard radar live, as the antenna rotated, you could hear a hum from the superstructure as the antenna passed it.  I would like to think it wasn't all 

That's probably from the oodles of poisoned pellets they scatter around to stop them shitting on the building and aperture.

[Neilm]

When I put chocolate in my pocket it melts anyway.

When I put chocolate in my pocket, it disappears (my excuse)

[Johnboy]

I've been studying for the GMDSS Maintainer license and the horror story which Grey Woolfe related frankly dovetails with the effusive, repeated safety warnings about even repairing slotted arrays and so on. While I don't feel particularly comfortable working with RADAR systems anyway, I have to wonder what legitimate damage microwave energy is genuinely capable of doing on a grand scale-- my gut says that the technology has been thoroughly tested for more applications than mere echolocation.

[bd139]

It usually causes non penetrating surface burns. Look for Active Denial System on YouTube etc.