Cecil,

There's a little check you can make on the accuracy of program SOLNOID3
regarding the self-resonant frequency of a solenoid.


The resonant frequency is due to the stray capacitance of the coil being in
shunt with the inductance.


The program allows the length of a coil to be stretched out until it is as
long as the wire it was wound with. Throughout the process, as L and C
change with coil length, the self-resonant frequency is calculated.


Resonant frequency is calculated up to the point when the original N turns
are stretched out into a straight length of wire. You can do a simple check
using your space-man's pocket calculator.


Does the program-calculated resonant frequency coincide with the resonant
frequency of the straight wire considered as a 1/2-wave dipole ?


Incidentally, when the coil is only partly stretched out, the program can be
used to estimate the resonant frequency of "Slinky's". Never having had a
Slinky I cannot say precisely how accurate this might be.
----
Happy Xmas to you and yours and all that sort of thing.
----
Reg.

Reg Edwards wrote:
The resonant frequency is due to the stray capacitance of the coil being in
shunt with the inductance.

Hi Reg, that answers my question. I'm glad you didn't go the
"lumped" route. Do you have a program that calculates the delay
through a real-world coil?

Incidentally, when the coil is only partly stretched out, the program can be
used to estimate the resonant frequency of "Slinky's". Never having had a
Slinky I cannot say precisely how accurate this might be.

Did you take into account that some Slinky's are made out of
plastic. :-)
--
73, Cecil, W5DXP