Electronic Analogue To A Slinky

[Bret Cahill]

Would alternating a lot of capacitors and inductors in series
approximate a Slinky spring?


Bret Cahill

 

[Charles Schuler]

Would alternating a lot of capacitors and inductors in series
approximate a Slinky spring?

A simple model would be a parallel resonant circuit (RLC). L and C would
dictate the oscillation frequency and R the damping factor.

 

[Charles Schuler]

A simple model would be a parallel resonant circuit (RLC). L and C would
dictate the oscillation frequency and R the damping factor.

But, if you are talking about a slinky walking down a flight of stairs,
forget about simple models.

 

[Homer J Simpson]

Would alternating a lot of capacitors and inductors in series
approximate a Slinky spring?

In what sense?


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[Bret Cahill]

Would alternating a lot of capacitors and inductors in series

But, if you are talking about a slinky walking down a flight of stairs,
forget about simple models.

Ah HA! Finally a situation where mechanics is more sophisticated than
electronics!

We have a Slinky that can walk down steps and you guys don't have
anything to compare..

Na na Na na NA NA.

It probably wouldn't be too difficult to make an electronic "slinky"
that could "walk" down a voltage.

It would make a really obnoxious car alarm.

Is it too late to cancel this post?


Bret Cahill

 

[jasen]

Would alternating a lot of capacitors and inductors in series
approximate a Slinky spring?

I think a slinky spring, being basically a coil, is mostly inductance :^)


If you're doing wave experiments with it however, it's a physical
delay line,

one way to make an electrical delay line is lots of inductors in series
and capacitors to ground.

--+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+-ww-+--
| | | | | | | | | | | | |
=== === === === === === === === === === === === ===
| | | | | | | | | | | | |
--+----+----+----+----+----+----+----+----+----+----+----+----+--


Bye.
Jasen

 

[Bob Eld]

Would alternating a lot of capacitors and inductors in series
approximate a Slinky spring?


Bret Cahill

No...Placing a number of capacitors and inductors in series simply lumps
them as one capacitor and one inductor. The inductance adds: L1 + L2 +
L3.... and the reciprical of the capacitace adds: 1/C1 + 1/C2 + 1/C3....etc.
The result is a single capacitance, a single inductance and a single
resonant frequency. Apparently you are looking for a coupled group of
resonators each separate from yet dependent on the other. There are circuits
like this. Look up chaotic oscillators.

 

[Bret Cahill]

them as one capacitor and one inductor. The inductance adds: L1 + L2 +
L3.... and the reciprical of the capacitace adds: 1/C1 + 1/C2 + 1/C3....etc.
The result is a single capacitance, a single inductance and a single
resonant frequency. Apparently you are looking for a coupled group of
resonators each separate from yet dependent on the other. There are circuits
like this. Look up chaotic oscillators.

As long as no new auto alarms come out of this . . .


Bret Cahill

 

[Baron]

No: That would be more like a transmission line representation !

 

[Charles Schuler]

But, if you are talking about a slinky walking down a flight of stairs,
forget about simple models.

Ah HA! Finally a situation where mechanics is more sophisticated than
electronics!


The analogies between the two are mostly simple ones. I little direct
experience, but I'll guess that finite element analysis would do a great job
of modeling a slinky doing slinky-like tricks. Bad news is that those
software packages are REALLY expensive (might be some low cost versions ...
again, not my field). Ansys and Comsol are two FEA tools that I have played
with (demos only). Neat stuff!

 

[Rich Grise]

Ah HA! Finally a situation where mechanics is more sophisticated than
electronics!

We have a Slinky that can walk down steps and you guys don't have
anything to compare..

Na na Na na NA NA.

It probably wouldn't be too difficult to make an electronic "slinky"
that could "walk" down a voltage.

It would make a really obnoxious car alarm.

Is it too late to cancel this post?

It is now. ;-)

So, write an equation for the motion of a slinky walking down the stairs,
and we'll simulate it. ;-)

Cheers!
Rich

 

[Rich Grise]

Ah HA! Finally a situation where mechanics is more sophisticated than
electronics!

The analogies between the two are mostly simple ones. I little direct
experience, but I'll guess that finite element analysis would do a great job
of modeling a slinky doing slinky-like tricks. Bad news is that those
software packages are REALLY expensive (might be some low cost versions ...
again, not my field). Ansys and Comsol are two FEA tools that I have played
with (demos only). Neat stuff!

But, that's not electronics, that's software. ;-)

Cheers!
Rich

 

[Bret Cahill]

So, write an equation for the motion of a slinky walking down the stairs,

and we'll simulate it. ;-)

That's why I came here. To see if it was worth screwing around with
the math. All I have is a qualitative understanding:

From the angular momentum POV it isn't much different than a ball

rolling down a hill or down steps for that matter.

The torque from gravity in the y direction acting to accelerate one end
about the center of mass adds enough angular momentum to keep it going.

The difference is at the end of each "step" the angular momentum needs
to go somewhere and it goes to the flip. After each flip the angular
momentum goes back to rolling the coil.

Both the ball and spring both have translational as well as angular
momentum.

From the energy POV, since it doesn't accelerate from step to step we

know all the potential energy for each step ends up as heat as the
coils slap together.

It might not be that ugly a problem.


Bret Cahill

 

[ehsjr]

But, if you are talking about a slinky walking down a flight of stairs,
forget about simple models.

I suppose it depends on what he means by
"approximate". You can make a simple stair
case with a counter driving voltage dividers.
Stuff the outputs through diodes into an RC
so that the steps take some time, start out
high and go to low. Heck, you can even make
the "electronic slinky" go *UP* the steps!

Ed

 

[Rich Grise]

.

know all the potential energy for each step ends up as heat as the
coils slap together.

It might not be that ugly a problem.

Are Slinkys really made of recycled piston rings? ;-)

Cheers!
Rich

 

[Rich Grise]

As long as no new auto alarms come out of this . . .

Most people ignore car alarms anyway. Did you ever see "South Park Bigger
Longer and Uncut"? A guy jumps out of a window and lands on some car,
which sets off the alarm. The car owner comes out, looks at the corpse
on top of his car, scowls, turns the alarm off, and goes back to whatever
he was doing before the alarm.

Cheers!
Rich

 

[Bret Cahill]

Lightening or anything sets them off so no one notices.

One guy in San Diego made millions off of auto alarms and financed the
recall of Grey Davis. When he realized he opened the door for Arnold
he pulled his funding but by then it was too late.

Unintended consequences seem to be the rule in crime and politics.


Bret Cahill


"The best laid plans o mice and men . . ."

-- Burns