4 ms·

It‘s amazing how much opposition there apparently was against AC current – a technology that noone is afraid of today.

Gibbon1 9y ago
The open question for me is why did Edison even bother with DC at all? A DC generator requires a commutator. If there is anything that screams dodgy, that would be it. Sliding friction. high current contacts. 60 times a second? Seriously?
- xxpor 9y ago
  Do incandescent bulbs last longer with DC, since they're not switching on and off 60 times a second?
  - cr0sh 9y ago
    There used to exist these "buttons" (for lack of a better term) that you could place at the bottom of a lamp socket to make your bulbs last longer. They were actually a diode shaped like a disc (more or less), that ultimately halved the amount of voltage going to the lamp (while also acting as a half-wave rectifier to form a noisy DC current). So in such an application - yeah, running a lamp at half its rated voltage would lengthen the life of the lamp (while reducing its brightness of course). There was once the argument that DC would cause the lamp filament to vibrate like AC would (in the presence of the Earth's magnetic field?) - and thus if you ran your lamp on DC it would last longer due to not being mechanically stressed (I think this was one of the pitches behind those buttons, too). I think it was later found that the argument had little validity, and was more a marketing pitch. That said, a lamp does experience a moment where, when the current (AC or DC) is switched on, the filament does "flex" - partially from magnetism, partially from thermal loading as it heats up. This flex, over time, does produce a mechanical stress on the filament. It's a major reason why incandescent lamps typically burn out when you turn them on.
  - lostlogin 9y ago
    Are they though? Bulbs take a brief period to turn off when hot and that cool down period is likely longer than 1/60th of a second.
rdtsc 9y ago
Just like in politics, a lot of that opposition was manufactured by PR. Apparently Edison's company publicly executed an elephant using AC current to show the "dangers of AC". https://en.wikipedia.org/wiki/Electrocuting_an_Elephant https://en.wikipedia.org/wiki/Electrocuting_an_Elephant
pmarreck 9y ago
Perhaps 100 years from now, it will be amazing how much opposition there was against human-caused global warming today – a connection that none may doubt then I blame politics for both

The open question for me is why did Edison even bother with DC at all? A DC generator requires a commutator. If there is anything that screams dodgy, that would be it. Sliding friction. high current contacts. 60 times a second? Seriously?

xxpor 9y ago
Do incandescent bulbs last longer with DC, since they're not switching on and off 60 times a second?
- cr0sh 9y ago
  There used to exist these "buttons" (for lack of a better term) that you could place at the bottom of a lamp socket to make your bulbs last longer. They were actually a diode shaped like a disc (more or less), that ultimately halved the amount of voltage going to the lamp (while also acting as a half-wave rectifier to form a noisy DC current). So in such an application - yeah, running a lamp at half its rated voltage would lengthen the life of the lamp (while reducing its brightness of course). There was once the argument that DC would cause the lamp filament to vibrate like AC would (in the presence of the Earth's magnetic field?) - and thus if you ran your lamp on DC it would last longer due to not being mechanically stressed (I think this was one of the pitches behind those buttons, too). I think it was later found that the argument had little validity, and was more a marketing pitch. That said, a lamp does experience a moment where, when the current (AC or DC) is switched on, the filament does "flex" - partially from magnetism, partially from thermal loading as it heats up. This flex, over time, does produce a mechanical stress on the filament. It's a major reason why incandescent lamps typically burn out when you turn them on.
- lostlogin 9y ago
  Are they though? Bulbs take a brief period to turn off when hot and that cool down period is likely longer than 1/60th of a second.

rdtsc 9y ago

Just like in politics, a lot of that opposition was manufactured by PR. Apparently Edison's company publicly executed an elephant using AC current to show the "dangers of AC". https://en.wikipedia.org/wiki/Electrocuting_an_Elephant https://en.wikipedia.org/wiki/Electrocuting_an_Elephant

pmarreck 9y ago

Perhaps 100 years from now, it will be amazing how much opposition there was against human-caused global warming today – a connection that none may doubt then I blame politics for both