How can I buy or make an electret with oriented dipoles?

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Discussion Overview

The discussion centers on the interest in purchasing or creating electrets, specifically those with oriented dipoles, as opposed to more common versions that rely on surface charge. Participants explore various methods and materials for making electrets, as well as the availability of commercial options.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses a desire to find or create an electret with oriented dipoles, mentioning traditional methods involving beeswax, carnauba wax, and rosin, while seeking newer materials and procedures.
  • Another participant suggests purchasing electret microphones from Radio Shack, providing details about the product and its specifications.
  • A participant who bought electret microphones reports disappointment in their lack of noticeable electrostatic properties, speculating that the charge may be insufficient for such demonstrations.
  • Concerns are raised about the nature of static cling films and whether they can be classified as electrets, with a specific interest in their charge type (ionic vs. oriented dipole).
  • One participant clarifies that electret microphones operate at low voltages and questions the expectation of attraction between the microphones, emphasizing their design as condenser microphones with built-in amplifiers.
  • Another participant reiterates the difficulty in finding suppliers for electrets, suggesting that manufacturers may not cater to individual consumers.

Areas of Agreement / Disagreement

Participants express differing views on the properties and applications of electrets, particularly regarding the effectiveness of electret microphones and the classification of static cling materials. There is no consensus on the best methods for creating or sourcing oriented dipole electrets.

Contextual Notes

The discussion highlights limitations in sourcing electrets and the potential misunderstanding of their properties, particularly in relation to the voltages involved and the nature of the materials discussed.

Lewis R
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I am interested in buying or making an electret - preferably the oriented dipole version - not the probably more common real or surface charge version. I have read about the old procedure of making an electret from a mixture of beeswax, carnuba wax and rosin, but I think that by now there must be newer materials and procedures that produce better and longer-lasting electrets. Any thoughts? Thanks
 
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You can buy them at Radio Shack. Price $3.79.


Electret Microphone Element with Leads
Model: 270-092 | Catalog #: 270-092

This omnidirectional microphone element has a wide 30-15,000Hz frequency response. Requires 4-10VDC.

Probably cheaper ones around if you go hunting.

These have an amplifier built into them and you need to add a load resistor of about 4.7K.
 
Thanks for the tip on the Radio Shack electret microphones. So I bought two microphones and removed their electret diaphragms, but I was disappointed to find they did not exhibit any noticeable attraction or repulsion to each other or to anything. Perhaps because the opposite sides of the diaphragm might be charged to only a few hundred volts ( adequate for microphone operation but inadequate for electrostatic demonstrations, which usually involve thousands of volts). To measure such a static-charge voltage I would need a special meter, which I don't have.
Since electrets are interesting, I thought I could easily buy them from science supply houses- but no such luck. I have read that electrets are used in microphones, air filters, copy machines and static cling films (for windows, stickers, etc.). Thus, I am thinking about buying some static cling stickers since they might be electrets. But I can't find any source that states definitely that static cling film is an electret, only that the film is made from PVC. And I would like to know which type of electret- ionic or oriented dipole. And what about the old child's toy, Colorforms (vinyl static cling stickers)? Are they electrets?
Thoughts? Thanks
 
Maybe we are talking about different things.

Electret microphones only ever work on small voltages, up to 10 Volts, maybe.
They are just condenser microphones with an amplifier attached.

I don't see why they would attract each other. They are just microphones and have no magnets in them and not enough electric charge to attract anything.
 
Lewis R said:
I am interested in buying or making an electret - preferably the oriented dipole version - not the probably more common real or surface charge version. I have read about the old procedure of making an electret from a mixture of beeswax, carnuba wax and rosin, but I think that by now there must be newer materials and procedures that produce better and longer-lasting electrets. Any thoughts? Thanks

It appears you're not alone. I have searched for some time to find a supplier, and they simply do not exist on the web. As I mentioned to someone else on the forum, I think electric manufacturers are not interested in selling to individuals, but only to other manufacturers.
 
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