DoN. Nichols wrote:

According to Jim Chandler :

Don Foreman wrote:


[ ... ]


And also #24, which they describe as a parallel circuit. Sure, the two lamps
are in parallel -- but they're in series with the switch...


Switches are not considered as part of the circuit for series/parallel
determination.

Jim Chandler


Perhaps not by diesel mechanics. They're treated the same as any
other circuit element in circuit network analysis. For example, they
are sometimes used in parallel with other circuit elements, as in the
question with three light bulbs.

98.


Still not considered a part of the load though, Don. As an amateur radio
operator (N5COT) and an Air force electronics tech. we never considered
a switch as p[art of the load. It is part of the pathway to the load
resistance only.


But switches can make logic arrays. In particular with relay
logic. An example on a CNC machine could be a series of switches (axis
limit switches) in series, with a parallel set of contacts on a manual
override switch (which would also limit axis speeds to a minimum to
allow you to move the axis with problems away from the limit switch.

And for normal automotive applications, there are multiple door
switches in parallel to control the dome light -- and those are in
series with a master switch which often has three positions:

1) Dome light *always* off.

2) Dome light switched by door switches. Any single door, or any
combination of doors open turns on the light, otherwise it is
off.

3) Dome light *always* on.

So -- they can reasonably be referred to as being in
series-parallel combinations.

Enjoy,
DoN.

But nowadays the dome light is probably controlled by the output of some
damn computer and you'd have to be a digital Houdini to figure it all out.

The dome lights in our two "21st century" cars slooooooowly dim down to
off under certain conditions of the doors, ignition, ambient lighting
and G-d only knows what else. I haven't bothered to study that enough to
understand it. That slow dimming to off suggest to me what dying might
feel like someday. G

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.