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Author Topic: Making an Electret, or several actually.  (Read 13326 times)

Grumage

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Making an Electret, or several actually.
« on: January 01, 2018, 07:49:05 PM »
Hello All and a happy new year.

I started a thread here at OUR a few days ago.

http://www.overunityresearch.com/index.php?topic=3577.msg66260#msg66260

I hope you'll forgive me for a copy/paste introduction?

Cheers Graham.

Grumage

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Re: Making an Electret, or several actually.
« Reply #1 on: January 01, 2018, 07:52:57 PM »
Hello Everyone.

I have always been fascinated by Electrostatic phenomena, my father demonstrating to me as a child the famous balloon on the ceiling trick, yes it goes way back.

As many will remember I built a modern day Franklin Electrostatic motor earlier this year with the intention of testing one of our members, Smudge theories. That’s still in the pipeline, BTW.

These devices have really grabbed my attention, particularly when Verpies pointed out that the forces generated can exceed both gravity and magnetism.

Over the Christmas holidays I have been playing around with some simple experiments moving small masses by Electrostatic means, but my goal is to try and build an attraction motor that uses segmented Electrets so that no external HV supply will be required.

I have opened this thread to ask if any members here have made successful wax Electrets and to document my own attempts as well.

I have " bumped " here in the hope that some/any of the contributors here at OU.Com might be able to help me with this rather interesting area of Electrostatics.

Cheers Graham.

Here's some You Tube links to my recent Electrostatic experiments.

https://www.youtube.com/watch?v=koJ0qHNWlBM

https://www.youtube.com/watch?v=kIwHqV1NpHs

https://www.youtube.com/watch?v=-4XlD4YP5Kc 

https://www.youtube.com/watch?v=u53Vwodew_Y

sm0ky2

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Re: Making an Electret, or several actually.
« Reply #2 on: January 02, 2018, 02:51:58 PM »
Hi Graham,


The effects you are describing are what my Swiss contacts claim as
the driving force of the Testatika machines.


This is best demonstrated using two Whimshurst machines
One physically rotated, the other connected in parallel
through the output terminals.
The second machine rotates by electric force.


One of our members named LidMotor has a nice collection of
experiments on his YouTube channel. A quick search there will
lead you to his channel.


Also TK shows us a few tricks he has learned.


Hope this helps.


Void

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Re: Making an Electret, or several actually.
« Reply #3 on: January 02, 2018, 07:02:31 PM »
Hi Grum. I have never made an electret, but I find this interesting about electrets:

"When the oil reaches room temperature, turn off the power supply and remove the electret. Immediately fold the aluminum foil forward over the surface in contact with the top plate, short-circuiting the electret. The foil acts as a 'keeper' and is analogous to the soft-iron bar placed across the open jaws of a horseshoe magnet to preserve the magnetic flux. Electrets properly short-circuited have kept for longer than five years without noticeable loss of charge.

Now comes the puzzler that stumps the experts. If the electret's polarity is measured directly after its manufacture, its charge will be just what theory predicts it should be. The negative surface of the electret will be that which made contact with the positively charged polarizing electrode, and vice versa. This agrees with the north-south polarity of a bar of steel magnetized by contact with a permanent magnet. In contrast with the behavior of a magnet, however, the charge on the electret begins to diminish immediately, and in about a week it will have fallen to zero. The charge then begins to build up in opposite polarity to a final value that may be several times as large as the original charge. This may take as long as three months. The negative surface of the stabilized electret will be the face that made contact with the negatively charged polarizing electrode. In other words, the charge will correspond in sign to the polarity of the high-voltage field. Just why this reversal takes place has never been satisfactorily explained."
Cited source: How to Make an Electret - the Device That Permanently Maintains an Electric Charge - by C. L. Strong - Scientific American, November, 1960
https://sites.google.com/site/polymericmatrixmaterial/how-to-make-an-electret


The statement that you should 'short circuit' with aluminum foil after making the electret and leave it for several months
short circuited like that, and the electret will change polarity during this period, and this reversed polarity can be even
stronger than the original charge. That is a pretty odd effect. If the charge separation is sealed into the cooled wax,
I would have thought that the electrostatic charge would remain fixed like that for a long time, but apparently the charge
somehow reverses over a period of a few months when 'shorted' with aluminum foil. Very odd effect indeed. :)

All the best...

Grumage

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Re: Making an Electret, or several actually.
« Reply #4 on: January 02, 2018, 09:03:24 PM »
Hi Guys.

Many thanks for the information.

Tinsel Koala linked to a nice little pdf on my thread over at OUR.

http://www.overunityresearch.com/index.php?topic=3577.msg66266#msg66266

I have downloaded it myself but cannot seem to place it here from my PC.

In that article it also mentions this polarity reversal over time but they are suggesting hours rather than weeks.

Here's my " dream " copied from my post over at OUR.

“ Rotor?? “

I have an idea of a simple attraction motor. Your thoughts on how it might work, if at all, would be appreciated.

A disc of thin Aluminium sheet is covered by a slightly larger diameter of Polycarbonate. The Polycarbonate disc has got slots milled through its thickness. These slots extend from the centre point radially, just the same as the segments of a Wimshurst machine. I cook the wax mixture and pour into the slots cover with foil then pole the assembly with a positive potential applied to the base disc. I make a second one done the same way.

I then propose to mate the two discs back to back and provide an axle to be fitted into a pair of bearings mounted in a vertical fashion. The final part is a “ U “ section metal “ attractor “ ?? That goes to a good earth and is placed so that the rotor can run between the faces. Finished!

The above was written a few days ago, I have now changed my thoughts towards using circular wax Electrets inserted into a pre machined Polycarbonate rotor.

As a further update, the poling mould is virtually complete its dimensions are 50mm diameter by 10mm wide cavity. Poling voltage will be approximately 40,000 Volts DC provided by two 20KV air ionisers in series.

Cheers Graham.

Grumage

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Re: Making an Electret, or several actually.
« Reply #5 on: January 02, 2018, 09:47:09 PM »
 ;)

Void

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Re: Making an Electret, or several actually.
« Reply #6 on: January 02, 2018, 10:41:02 PM »
In that article it also mentions this polarity reversal over time but they are suggesting hours rather than weeks.

Hi Grum. I don't know, but maybe the charge reversal time varies depending on the exact composition and portions
used in the electret material.

All the best...


sm0ky2

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Re: Making an Electret, or several actually.
« Reply #7 on: January 03, 2018, 12:38:44 PM »
+ - + -


+        -+        -




- / / +




The above is a visual representation of thermodielectric induction
The center two charges are on either side of the dielectric
The outer charges are on the conductors


While the dielectric isulative, it’s surface charges conduct onto the conductor
in the same way a negative charged balloon transfers its charge onto the
objects it attracts.


There are two effects
First induction
Then conduction
(then induction again)


@void yes, Faraday said it does vary with materials

Grumage

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Re: Making an Electret, or several actually.
« Reply #8 on: January 03, 2018, 01:29:31 PM »
Hi Guys.

Ok, my poling mould is nearing completion and the raw materials have arrived from their various locations around the UK.

I have 500 grams of  Carnauba flakes, 500 grams of Rosin crystals and 200 grams of Beeswax. The recipe states a 45%, 45%, and 10% Beeswax by weight.

Am I correct that 100 grams of Beeswax added to the Kilogram of the other ingredients is right?

Cheers Graham.

sm0ky2

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Re: Making an Electret, or several actually.
« Reply #9 on: January 03, 2018, 02:38:11 PM »
Hi Guys.

Ok, my poling mould is nearing completion and the raw materials have arrived from their various locations around the UK.

I have 500 grams of  Carnauba flakes, 500 grams of Rosin crystals and 200 grams of Beeswax. The recipe states a 45%, 45%, and 10% Beeswax by weight.

Am I correct that 100 grams of Beeswax added to the Kilogram of the other ingredients is right?

Cheers Graham.


110


Or you can downsize it like Webby suggests.


It is the total that you want to take the % of

conradelektro

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Re: Making an Electret, or several actually.
« Reply #10 on: January 03, 2018, 02:54:29 PM »
It might be interesting to mix some 19th century electrets, but nowadays one can use plastic materials. I often use Plexiglass (Polymethylmethacrylat, PMMA) https://en.wikipedia.org/wiki/Poly(methyl_methacrylate)

The best is to rub the surface (e.g. only one surface of a disk) with real fur. I bought an old fur hat, be careful, it has to be real fur. Cat fur or fox fur works best. You want fur with very fine hair. The fur has to be dry.

The best surface is a disk. If you use other shapes, you could get several areas with opposite charge. Good shapes are also spheres (hard to get from Plexiglass) or tubes (one can use PVC tubes).

Many plastic materials work, but one has to find out which ones are best. Also many plastic foils work, but are hard to handle. I prefer thin plastic sheets which are stiff and can be cut with scissors.

https://www.youtube.com/watch?v=notE4ugcgvk

https://www.youtube.com/watch?v=_TmoQFEk8d0

https://www.youtube.com/watch?v=PzoUiZnR5QA

Greetings, Conrad

Grumage

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Re: Making an Electret, or several actually.
« Reply #11 on: January 03, 2018, 04:09:11 PM »
Thanks Guys.

I’m off to the workshop to mill the “ sprue “ hoping that 5mm depth will be sufficient “ head “ to allow for material shrinkage into the mould cavity.

Many thanks Conrad for the additional information about Electrets from plastics.

Cheers Graham.


Void

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Re: Making an Electret, or several actually.
« Reply #12 on: January 03, 2018, 05:35:34 PM »
I have 500 grams of  Carnauba flakes, 500 grams of Rosin crystals and 200 grams of Beeswax. The recipe states a 45%, 45%, and 10% Beeswax by weight.
Am I correct that 100 grams of Beeswax added to the Kilogram of the other ingredients is right?

Hi Grum. If you use 500g of carnauba and 500g of rosin and 100g of beeswax, you would calculate
the percentages like this:

First calculate the total weight:
500g + 500g + 100g = 1100g.

Then, to calculate the percentages by weight of the carauba and rosin:
(500 / 1100) x 100 = 45.45% for each

The percentage by weight of the beeswax is:
(100 /1100) x 100 = 9.09%

So, that is close to 45%/45%/10%.

P.S. It probably wouldn't matter much, but 500g + 500g + 111g would be even closer to 45%/45%/10%. :)


All the best...

Grumage

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Re: Making an Electret, or several actually.
« Reply #13 on: January 04, 2018, 12:41:06 PM »
Update.

Well, I didn’t manage to finish the mould because number 3 son who’s had a little time off work recently finished a project he’d started some nine years ago.

https://www.youtube.com/watch?v=-kNKswjpc20

This was one of many different  casting kits that I used to market a decade back.

I did however carefully measure the ingredients and cook up a batch of wax. The smell wasn’t too bad, almost organic.

I used clean Stainless Steel utensils got all the air out and allowed the mixture to cool and set. Upon touching the top surface a loud crack was heard, I assume the wax had adhered to the edges of the bowl I had used and then suddenly released. It promptly shattered into many smaller pieces.

From this exercise I noticed that there was little to no “ slump “ in the material so a deep “ sprue “ won’t be needed on the mould. A good polished surface however, is a must!

More to come, cheers Graham.

Grumage

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Re: Making an Electret, or several actually.
« Reply #14 on: January 04, 2018, 08:04:03 PM »
Hello Everyone.

How ( NOT ) to make an Electret. Take 1.

https://youtu.be/QEYXeuAxIqQ

                        :)

Cheers Graham.