Hendershot Replications

[mlurye]

morpher44,
Are you using dual coils in your build? If you do where did you buy it?

[morpher44]

dual coils...

morpher44,
Are you using dual coils in your build? If you do where did you buy it?

By "coils" I assume you means the Hendershot coil.
I'm working on a 2nd coil ... but it isn't finished yet.
You can buy: wire, 1/8" dowels, wood, electrical tape, etc.
from hardware stores, radio shack, or online at various electronic stores.

[mlurye]

By "coils" I assume you means the Hendershot coil.
I'm working on a 2nd coil ... but it isn't finished yet.
You can buy: wire, 1/8" dowels, wood, electrical tape, etc.
from hardware stores, radio shack, or online at various electronic stores.

morpher44,
Sorry for being unclear I meant electromagnet with double coils.

[morpher44]

buzzer

morpher44,
Sorry for being unclear I meant electromagnet with double coils.

Oh that is just a buzzer "made in china".
I got that at a surplus electronics store for about $1.50 USD.
I had to solder an extra wire to gain access to the other coil wire.

Hendershot used solenoids extracted from doorbells.

You can also attempt to wrap your own solenoids.
There is probably a large benefit in using soft-IRON cores
instead of steal. You can try welding rods as the core which
is what the "Bedini SSG" folks use.

[mlurye]

Did you buy it online? Can you give me a link? It's easier to buy it for 1.50 then do it yourself
In what direction did you wind coils (clockwise/counter clockwise)?

L1
L2
L3
L4

[morpher44]

buzzer / coils

Did you buy it online? Can you give me a link? It's easier to buy it for 1.50 then do it yourself
In what direction did you wind coils (clockwise/counter clockwise)?

L1
L2
L3
L4

Its a bit hard to find a dual-coil buzzer online since you cannot see
inside them.
Here is a link:
Thomas & Betts DH920 AP Enclosed Buzzer - Electrical & Lighting - Wireless Doorbell Chimes & Buttons - Bells & Buzzers

There are many many buzzers & doorbells out there.

I wound all coils L1-L4 the same direction -- CCW facing down into coil
from top. I don't think this direction matters except for all coils
on the same form must be in the same direction.

I believe Hendershot wound his coils in the same direction -- i.e. both
coils wired the exact same way ... and then in the circuit he
wires they differently.
Had the coils been wound one CCW and the other CC,
his circuit might change to swap the coil wires for the CC coil, for
example.
I think these phase relationships matter ... and some experimentation
is in order to get the correct circuit diagram ... depending upon
how you wrapped your coils.

[morpher44]

Non-Conservative Fields

Does anyone have experience with the concept
of "negative reactance" and how to exploit it?

I've started this other thread on Non-Conservative Fields.
This concept is so foreign to me and mutual inductance
effects in coils do such odd things.

A coil by itself would behave in a very linear way with
respect to inductance.
But pulse that coil with energy from some magnetic field
that you've produced and Faraday's induction law
would have you add yet another voltage to the mix.
Time it just right with respect to waves you are sending
through the coil and you have created a regenerative
interference.

Magnets produce a nice steady magnetic field.
Solenoids place near magnets can perturb that field ..
bend it ... tweak it.

The Earth's magnetic field is just there for you to exploit
in the absence of other fields.

So "if" you could tweak your magnetic fields near your coils,
coils with a high magnetic permeability, you can induce a current
in them.
Certainly one way is the rotating generator.
But rotation is not the only way of doing this ... and the
shaft providing the rotation will be subject to the back-pressure
(mechanical loss).

There are possibly several other ways of
creating a wiggling magnetic field ... ones that are not
subject to this back-pressure.
Put a magnet into resonance, for example, and the
oscillating field lines will spread out around it. Nearby coils
will certainly "feel" the oscillation ... and Faraday's induction will occur.
These coils would be stationary.
The magnet need not move great distances.
Rather, its vibrations can be in the millimeter to micrometer scale.
If the magnet is STRONG, however, its field lines will reach out
quite far.

I suspect also that if near the magnet is placed a metal core -- soft iron --
and if that magnet is allowed to come in contact with that core, and then broken away from it ...
that the magnet SNAPs out a much larger pulse.
So by resonating a magnet and vibrating it on-and-off metal,
there is a crashing pulse spike that conveys lots of magnet current.
Magnets, when they get really really close to metal, can align the
atoms so much better. Pull it away rapidly, and the metal responds
to the earth's field instead.

With a cylinder metalic shape, if you can create a SPINNING field in
the cylinder, and there is a coil wrapped around it, you can again
get induced current ... even though it appears as if nothing is moving.
There is something moving, however. The field is moving.

[mlurye]

morpher44,
I would agree that all coils should be wound in the same direction. Based on the Ed Skilling picture and Mark Hendershot comment on page 119(Barry Hilton book) coils were wound in counter clockwise direction.
But I don't think buzzer on the link has correct coil for electromagnet, the one that was used in Hendershot device was 110V.

Its a bit hard to find a dual-coil buzzer online since you cannot see
inside them.
Here is a link:
Thomas & Betts DH920 AP Enclosed Buzzer - Electrical & Lighting - Wireless Doorbell Chimes & Buttons - Bells & Buzzers

There are many many buzzers & doorbells out there.

I wound all coils L1-L4 the same direction -- CCW facing down into coil
from top. I don't think this direction matters except for all coils
on the same form must be in the same direction.

I believe Hendershot wound his coils in the same direction -- i.e. both
coils wired the exact same way ... and then in the circuit he
wires they differently.
Had the coils been wound one CCW and the other CC,
his circuit might change to swap the coil wires for the CC coil, for
example.
I think these phase relationships matter ... and some experimentation
is in order to get the correct circuit diagram ... depending upon
how you wrapped your coils.

[morpher44]

magnet / solenoid / bar

But I don't think buzzer on the link has correct coil for electromagnet, the one that was used in Hendershot device was 110V.

This statement from Barry Hilton book:

"When a field is induced in the solenoid cores through electrical action
within the bobbin windings, the magnetic force of the solenoid overcomes
the resistance of the permanent magnet and draws the bar toward the
solenoids. At the appropriate point of the electromagnetic cycle
the cores momentarily cease to be magnetically active, and the clapper
returns to the poles of the magnet."

So I think this is what is to be achieved by whatever means
you can invent to do so.
There is a large variety of magnets (Hendershot used
a STRONG 3-pole Radar magnet ... a bit hard to find).
There are a many different types of solenoids -- with varying
wires gauges and configurations.
And the placement of the bar is a mystery.

R.H. Crabb appears to have used something closer to a relay.

Also in Barry Hilton's book, page 134, there is a discussion
of the "Fluxgate phenomenon" and a speculation that
Hendershot figured out how to exploit that effect.

A modern fluxgate magnetometer has a toroid that has
one half brought into saturation, the other half, 180 degrees away
is not yet saturated, creating a flux imbalance.
This non-symmetric situation induces voltages in a
secondary winding.

Perhaps Hendershot was doing a similar 180 degree flux
imbalance trick in his two solenoids (and larger coils).

[mlurye]

morpher44,
It is good explanation on how buzzer works, but I do believe there is more to it then we can observe.
And I don't want to speculate on how this device works, the only person who knew it was Hendershot.
About magnet, I'm going to use 2 cylindrical neodium magnets fixed on a plate and I'm planning to use a piece of wood between magnets and bar to regulate strength of magnets.

[mlurye]

Can someone translate this document http://www.overunity.de/index.php?ac...downfile&id=14 from German to English?
Tried it with Google translator, doesn't work to good
Thank you in advance.

[morpher44]

Hand Wound Capacitor

The Hendershot circuit calls for a .0078 MFD capacitor.
There is also mention that it can be 1.3 MFD ... a large difference.

Using the formula for a plat capacitor, and assuming
a wax paper thickness of .001 inches
and dielectric constant of about 2.5,
a rough calculation for capacitance results in :

Enter width of plate (inches). > 91.125
Enter height of plate (inches) > 2.75
A = 0.161673 sq meters
Distance between plates (inches) > .001
Dielectric constant (farads/meter) > 2.5
C = 0.140894 uF

This does not account for the cylinder which might add
capacitance ... and the wrapping style, which has
overlapping plates.

This is leading me to conclude that the capacitance
is larger which actually makes sense if he was
trying to create a tank circuit that responds better
-- has resonance -- down in the buzzer frequencies
of 60 to 200 Hz.

The Barry Hilton document mentions the capacitance value
doesn't matter ... as long as both hand-made ones
are the same value with 1% to 2% (a challenge in itself).

But I think the capacitance value does matter if you don't
want to attenuate the buzzer frequency.

So I'm leaning toward the idea that these capacitors have
a larger value than 7.8nF.

[Joit]

Can someone translate this document http://www.overunity.de/index.php?ac...downfile&id=14 from German to English?
Tried it with Google translator, doesn't work to good
Thank you in advance.

Yuk, you make me work. i will do what i can at the Weekend, when i got more Time.

[morpher44]

hand wound capacitor experiment...

Using the formula for a plate capacitor, and assuming
a wax paper thickness of .001 inches
and dielectric constant of about 2.5

I just hand-wound another capacitor respecting
the instructions a bit more carefully.
I have one 92 x 2.75 inch plate, wax paper,
and then two plates of about 45 x 2.75 in with
a gap between them.

Wrapping around the cylinder proved to be
very difficult because I had trouble
keeping it taught and making it line up.
I thus had to loosen it up a bit and struggle with
it until it was all wound.

After doing so, I measure a capacitance of about 12nF.
Using my calculator:

Enter width of plate (inches). > 92
Enter height of plate (inches) > 2.5
A = 0.148387 sq meters
Distance between plates (inches) > .0105
Dielectric constant (farads/meter) > 2.5
C = 0.012316 uF

implying that even though the wax paper might
be around .001 inch thick, my sloppy capacitor
has an average distance between plates more
on the order of 10 paper thicknesses give or take.
Apply pressure to the cylinder would
have the affect of increasing the capacitance as the
plates are physically moved closer.
In this way, the capacitor can be made sort of ---variable---.

But, an interesting insight here is that Hendershot's
capacitor *may have been* sloppy as well ... with
a capacitance that wiggles around as the thing vibrates.
These physical vibrations -- originating from the magnet / solenoid --
could perturb the results.
Hendershot would seal everything in paraffin -- probably
to keep his coils and capacitor from being too wiggly.

I think I'll try this new "sloppy" capacitor out ... and see what occurs...

[morpher44]

better capacitor

I think I'll try this new "sloppy" capacitor out ... and see what occurs...

Ah. I am seeing better results.
With the new capacitor I can now make a neon bulb light
using only a 1.5V D cell with a 20mA current draw (30mWatts).

Neon bulbs require high voltages ... and so with the new capacitor,
if I remove it from the coil and put it OUTSIDE the coil, I can
get much larger ringing ... much higher voltages to the load.
Yet, at the same time, I think it reduces the current back
to the solenoid, make it harder to get going with the magnet.
When I put the cylinder back in the coil, which appears
to increase the frequency of the ringing -- lowering the voltage --
the relay is easy to get buzzing with the magnet nearby.

When I use a 6V battery, neon lights brighter with 67mA (.402Watts).
This is very much a function of the pulse rate -- frequency -- however.
I can vary the frequency using the magnet ... 67mA was
the lowest frequency before it stops. I can up the frequency,
consuming upwards to 1/2 watt as the Neon lights brighter.

So the improvement here, I think, is to use a capacitor
respecting the Hendershot dimensions of about 92 inch by 2.75 in.
This larger area appears to yield better ringing in the tank circuit,
which is then fed back into the circuit proper.

I experimented with moving the relay / bar / magnet
around physically near and away from the Hendershot coil
to see if the induced voltages would change.
I didn't notice very much happening with respect to that....
although this was just a quick experiment.

I was wondering about electric fields within coils and
see that this physics problem is a bit tricky.
I found this paper ... which is interesting.

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and here I found this quote:

5244-5248

"The time-varying electric field inside a solenoidal coil is measured using a new sensor that minimizes the
field disturbance. The experimental results clearly indicate that the main field inside a solenoidal coil is not
in the azimuthal direction, but in the axial direction. It is shown that this axial field is generated by surface
charges, which are formed to cancel the inductive field inside a conducting wire. "