Menticol
Active Member
Hello guys!
I have a very basic question than haunted me since I watched the movie Apollo 13, years ago. When giving some battery readouts, the astronaut mentioned something like this (I don't remember the exact literal conversation):
Battery A: Eleven volts, two amps.
Battery B: Zero volts, two amps.
Battery C: Five volts, zero amps.
I understood A and C conditions, but not B. If the battery is dead and no voltage is present, how can circuit B draw current from it?
The question raised again today when I powered a small Flyback transformer using my LM317T based power supply. PSU output voltage indicator fell to zero, even the pilot LED light turned off, but the arc at the end of the flyback was present.
PS: The original question was for DC, but while searching for an answer I found this post https://www.electro-tech-online.com/threads/design-a-zero-to-20v-20a-lab-supply.112573/. If at some point AC voltage crosses 0, why current doesn't drop to zero too?
I have a very basic question than haunted me since I watched the movie Apollo 13, years ago. When giving some battery readouts, the astronaut mentioned something like this (I don't remember the exact literal conversation):
Battery A: Eleven volts, two amps.
Battery B: Zero volts, two amps.
Battery C: Five volts, zero amps.
I understood A and C conditions, but not B. If the battery is dead and no voltage is present, how can circuit B draw current from it?
The question raised again today when I powered a small Flyback transformer using my LM317T based power supply. PSU output voltage indicator fell to zero, even the pilot LED light turned off, but the arc at the end of the flyback was present.
PS: The original question was for DC, but while searching for an answer I found this post https://www.electro-tech-online.com/threads/design-a-zero-to-20v-20a-lab-supply.112573/. If at some point AC voltage crosses 0, why current doesn't drop to zero too?
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