Jim Wilkins wrote:
"Tom Gardner" Mars@Tacks wrote in message
news
On 2/26/2014 9:20 PM, RogerN wrote:
"Tom Gardner" wrote in message
...

Thanks for all the replies and knowledge. My other battery
charger is a
one pound electronic machine. It works OK, supplies 2, 6 and 12
amps and
has all sorts of buttons and lights! What it won't do is charge a
totally
dead battery...thus repairing the old Craftsman. It displays:
"BAD
BATTERY" and I have to hook-up jumper cables from another vehicle
to get a
few percent of a charge to get the electronic charger to work.

I also confess I don't know enough about electronics. Is there a
good book
to start with that isn't too stupid yet not over my head? I think
I can
still learn stuff.

Comparing to piping, hydraulics, fluidics, pneumatics...

Volts are pressure
Amps is flow
Resistance is opposition to flow, a restriction in the line.
Power (watts) is the product of flow and pressure.

Rectifiers are like check valves.
capacitors are like storage tanks, accumulators or air tanks.
transistors are like pilot operated valves

AC would be kind of like a piston pump with no check valves, the
power goes
one way and then the other.
So. using this back and forth fluid could drive a piston one size
that is
connected to a different size piston, either increasing pressure
and
decreasing volume, or increasing volume and decreasing pressure.
That would
be kind of like a transformer, it takes alternating current to make
it work.
So if you transformed your pumps force and pressure, it could be
changed
after the transformer by adding check valves at that point.

The old fashioned battery charger transforms the line voltage to a
lower
voltage at a higher current. Then a rectifier causes it to flow
only one
way into the battery.

Magnetic field going through a wire induces a voltage in the wire,
not sure
what that would compare to in hydraulics. The magnetic field
inducing
voltage has to do with transformers, motors, inductors, antenna,
and other.

RogerN




Good analogies Roger!

The water analogy of pressure = voltage, flow = current is useful when
you are first learning about Direct Current circuits, but it falls
apart quickly for Alternating Current because moving water's inertia
isn't the same as inductance, and we don't have the hands-on intuitive
experience with AC reversing flows that we do with DC garden hoses.

Gas is actually a better analogy than liquid for electrcity, but once that
makes sense you no longer need the analogies anymore. Oh well.