diverted from
Got SmartBook G138 Yesterday - Need Advice!
ah, this brings back fond memories
(not so fond for my teachers when they were marking my exams papers!
) ...
Here's a revision for myself ...
In Fig 1,
ok, while we are at it ...
... if your device has a 3A fuse, and there is another device drawing 5A *and* in series with this device ... the 3A fuse will blow.
Internal resistance seen for L1 is 2ohm while L2 is 1.2ohm total resistance in series is 3.2ohm. Resultant current is 12v / 3.2ohm = 3.75A. This would blow the 3A fuse while the L2 load would still be underpowered. This assumes that both devices run at full load.
In Fig 2,
In order for L1 and L2 to run properly, a zener diode is introduced such that it creates a constant 6v voltage drop. ok, don't quiz me on how that is done or is possible.
... I can only think of a zener diode for now, without changing other parameters of the circuit ... hahahaha In the case of a diode, its current rating is more like that of a fuse, ie it will allow up to 5A of current to pass through without blowing.
The parallel load of L1 + L2 would be 3A + 4A = 7A ... in this case, this would blow the 5A fuse or the 5A diode ... prob the fuse in the power supply first, if not both.
For standard electrical wiring, appliances are almost always in parallel. Hence when the total power from all appliances on those multi-socket power slab exceeds the power rating on the wall socket
(typically 13A for normal usage, 15A for fridge, washing machines and stuffs, higher for industrial machines
), the fuse on the MCB
(Main Circuit Breaker
) would trip
(or blow in older setup
).
In parallel setup, another phenomena one may experience is how when certain heavy load devices start up in the house or office, the lights would dim for a sec. This is due to the inertia for the power supply from the mains to react to the sudden increase in load.
ok, I'm not sure if I am still making sense here ...
And please correct the diagrams where necessary ... electric circuits are really a faint memory for me already ...
(series.jpg)
(parallel.jpg)Attachments
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series.jpg (8KB - 11 downloads) parallel.jpg (11KB - 10 downloads)
