Re: Electrets (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 19 Jan 2004 10:59:38 +1030
From: Matthew Smith <matt@xxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Electrets (fwd)


> Matt: The original electrics were made with wax, but any insulating resin
> like polyester ( fiberglass)  will make much more durable electrics. Any
> flyback coil can provide more than enough voltage to charge them while the
> resin hardens.Only voltage not power is required. A flyback circuit from a
> old TV or monitor will give over 20  kV.
>    Robert   H

Thanks for that, Robert.

So - how does this sound?  I take a short length of PVC tubing and either put a
metal plug in the base or glue it to a metal disc.

Fill with polyester resin with the minimum amount of hardener (slowest cure) and
sit an electrode (a coin?) on top with some restraing to stop it from sinking.

Apply HV and wait...

Being used to thinking capacitors, should my electret be broad and short as
opposed to narrow and tall?  In other words, small electrode spacing, large
surface area as opposed to the other way around.

Seems like a good, cheap, opportunity for experimentation here using "common
household materials" (I always have polyester resin to hand, so this counts as
household to me).

Cheers

M

-- 
Matthew Smith
Kadina Business Consultancy
South Australia
http://www.kbc.net.au