Circuit Question.

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olivergw

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Hi Guys,

I have been looking at this diagram a friend showed me - of 2 lightbulbs, 2 switches and wire in between, he has put a truth table and he asked how does this circuit work - he said he there is nothing hidden.

he may be pulling my leg i dunno - i have copied it out onto paper then scanned, as it was originally written on a scrap bit of paper in a pub so... hehe

**broken link removed**

**broken link removed**

thanks Ollie
 
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Is it? i have drawn it identically to how he did - he has done the boolean for it too.

As . Bs = Al

As . Bs = Bl

by 1 i mean the switch is closed and 0 open
 
Gcity gave you the right answer. If either switch is open the lights will never light up. Also if both switches are close both lights will light.
 
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If switch A affects only light A and switch B affects only light B, then...

there are hidden parts.

What did the demo hardware look like?
 
It would work with hidden diodes and AC power but the brightness would be at one to four levels.
I have not thought about this very long so I'm just guessing.
 
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flat5 said:
It would work with hidden diodes and AC power but the brightness would be at one to four levels.
I have not thought about this very long so I'm just guessing.
Click to expand...
With a hidden diode across each switch and each lamp, the truth table is correct, and there will only be two brightness levels: Off and half power.
 
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flat5 said:
I see. With both switches closed the bulbs are still in series so half power.
Click to expand...
When one switch is on and one is off, the corresponding bulb only conducts during a half cycle. When both switches are on, each bulb conducts on alternate half cycles. The half cycle accounts for the half power. Actually, when only one switch is on, the diode across the other bulb conducts on one half cycle, so the bulb has a miniscule amount of current flowing through it.
 

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