street lights?

[things]

I think you'd appreciate the 50V/15A switch mode PSUs we do at work, they have a tendancy to explode on test... and boy do they go with a bang. Normally they blow the covers off a quad of high power FETs and vaporise some components. Sometimes it even catches fire!

COOL, i want to see that. what the whole thing explodes or do some of the components explode and causes the rest to blow? why do they blow? is it faulty components?

 

[spuffock]

Switch mode supplies? Usually some stupid buggre fits the electrolytics the wrong way round. Funny, he's been there since he left school, he'll be sixty next week. Nobody ever told him.
Come to think of it, that test engineer that just flew out into the aisle in a cloud of smoke looks familiar too.......................................

 

[ThermalRunaway]

Switch mode supplies? Usually some stupid buggre fits the electrolytics the wrong way round. Funny, he's been there since he left school, he'll be sixty next week. Nobody ever told him.
Come to think of it, that test engineer that just flew out into the aisle in a cloud of smoke looks familiar too.......................................

We've had that happen where electrolytics get fitted the wrong way around, but usually the cap explodes and that's about it. I think the problem with these particular PSUs is poor design as the FETs self destruct and it causes a cascade failure through the rest of the circuit resulting in quite an explosion indeed!
Quite a curious thing is that the bad FET survives, it's the good ones that explode!

Brian

 

[moody07747]

i have been wondering for many years how do they turn on the street lights along side the road. is it some sort of night dection or a pulse of current or does some guy just sit in front of about 500 switches turning them on at the right time . if any one knows how please let me know

photo cell...

and ya know what?
there's no 8 million switches...one for each house at the power company either
they turn your power off by taking out that meter and putting rubber boots on the terminals.

I always used to think some guy had the fun job of flicking each switch. lol

 

[plot]

Some have a light sensor at a main control box, which is why you sometimes see 30 highway lights come on at once. The norm is to have the light sensor on each light though, which is why some street lights go out every time you drive by them (sensor is aimed the wrong way!)

 

[Speakerguy]

When I was in high school, my hooligan friends and I would go around driving at night with a Q-beam spotlight (1M candlepower parabolic spotlight) and just drive down the road turning off the streetlights. They come back on as soon as the light is off and the bulb fires again (2-3 minutes for HID lamps like sodium or mercury vapor).