Thread: why 12V?
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Old March 7th 17, 08:43 PM posted to uk.tech.digital-tv
Woody[_5_]
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Default why 12V?


"Bill Wright" wrote in message
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So many things run on 12V DC. Firstly, why has that become the
standard? Is it all because of the nominal voltage of a car battery?
Secondly, wouldn't 24 or 48V be more convenient for many things?

I heard a few years back something about new cars being 48V in the
near future. Did it ever happen?


There seems to be or have been a number of 'standard' voltages.
6V was used on motorbikes and some cars - the 'Puddle Jumper' a.k.a.
Renault 4 for example - and those big torches of which the battery
formed part of the unit.
9V for portable radios - remember the PP3 and PP?
12V - nuff said
19V seems to be a very common voltage for laptop chargers
24V for commercial vehicles and trains(?)
48V for telephone systems and associated microwave links and nowadays
fibre equipments and always positive earth
90V used to be used for batteries in old portable valve radios
(remember them Bill?)
100V was also common - I used to have a SMPS mared 100/12 i.e. 100V
12A

I bet there's a lot more, but equally for battery supplies I would
think there is more 12V and 48V than anything else.


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Woody

harrogate3 at ntlworld dot com