For those who are interested in the numbers, the
capacity between two cars is somewhere around 1000 pf
car-to-car.
Which means that any one car to ground is probably
something like 2000 pf or thereabouts.
Jim
"jim rozen" wrote: (clip) capacity between two cars is somewhere around 1000
pf car-to-car.(clip)
^^^^^^^^^^^^^
Interesting fact, Jim, but where will I get a chance to use it? :-) Also,
since capacitance is dependent on the distance between the "plates" (cars),
what is the distance at which this figure is correct? Please respond soon,
in case I have to know.
Jim,
Does this mean 1000 pf is the capacitance of two cars very close together
with each forming one plate of a capacitor?
Bob (tired of the antenna thing) Swinney
With the earth in between. The implication is that
one car to ground is about 2000 pf. This is within
a factor of two from a simply calculated value, with
10 cm being the separation, and 10 sq M of plate area.
What this says is that at 1 MHz, the car body is coupled
to the ground via an approximately 80 ohm resistor. This
is large enough that there could be significant rf voltages
developed on the exterior of the car body at that frequency.
It implies that Jerry's suggestion (at am frequencies
the whip may be an electrostatic probe to measure the
body voltage) is indeed plausible.
Jim
What was the relative humidity?
Gunner
It's better to be a red person in a blue state
than a blue person in a red state. As a red
person, if your blue neighbors turn into a mob
at least you have a gun to protect yourself.
As a blue person, your only hope is to appease
the red mob with herbal tea and marinated tofu.
(Phil Garding)
Jim,
I have found the capacitance between cars to increase with the
distance. In fact, with the cars 6 inches the capacitance is zero.
Unless you use real skinny people. Then the capacitance rises with the
length of the cars.
ERS
Back in the good old days we used to charge our cars up with a model T
spark coil and a groundwire. Until the charge wore off, anyone touching
a door handle would get quite a jolt.
Engineman1
Is that free air capaciatance or using an oil dielectric?
If using an oil dielectric have you noticed any variation in changing
from 10W-40 to 5W-50??
Enquiring minds want to know-
H.
>jim rozen wrote:
>
>
>>For those who are interested in the numbers, the
>>capacity between two cars is somewhere around 1000 pf
>>car-to-car.
>>
>>Which means that any one car to ground is probably
>>something like 2000 pf or thereabouts.
>>
>>Jim
>>
>>
>>
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.