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Home > Archive > Electrical Engineering > July 2005 > Variable Capacitor??
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Variable Capacitor??
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| gtslabs 2005-07-13, 6:25 pm |
| Is there shuch a thing as a variable capacitor? I am planning on
tunning my phase converter with run capacitors and did not know which
size would be best. I plan on testing it with no load and full load and
finding the best capacitance to balance my amps and volts.
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| Palindr☻me 2005-07-13, 11:25 pm |
| gtslabs wrote:
quote:
> Is there shuch a thing as a variable capacitor? I am planning on
> tunning my phase converter with run capacitors and did not know which
> size would be best. I plan on testing it with no load and full load and
> finding the best capacitance to balance my amps and volts.
>
Yes there are such things, but only for relatively small
values of capacitance.
A capacitor substitution box is probably what you are
after - you can buy posh multi-decade ones (ebay often has
them). Make sure it is rated for the voltages which you are
planning to use it with.
Or you can simply get a handfull of standard values,
adequately rated, capacitors and make your own simple
substitution box.
--
Sue
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| ngdbud@hotmail.com 2005-07-27, 12:21 am |
| Yes! there is such a thing as a variable capacitor, although as
Palindr=E2=98=BBme said i've never seen a value above the pico farad range.
Variable capacitors are much more common than you might think. They are
the most common way to tune small radios. The next time you get your
hands on a $5 radio or some price in that area open it up, i can almost
guarentee there will be a small translucent box with a rod sticking out
of it connected the tuneing knob. Turn the knob and look through the
plastic box, you should see metal plates moving inside.
this url will take you to a site that tells you how to build your own
(notice it's a radio site) http://www.eham.net/articles/5217
This one will take you to site that briefly describes variable
capacitors, you'll have to scroll down almost to the bottom
http://www.kpsec.freeuk.com/components/capac.htm
This web address will take you to Froogle, google's selling site
http://froogle.google.com/froogle?q...3D100&hl=3Den&=
lr=3D&rls=3DGGLG,GGLG:2005-28,GGLG:en&tab=3Dwf&scoring=3Dp
Enjoy!
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| Repeating Rifle 2005-07-27, 3:21 am |
| On 7/26/05 7:36 PM, in article
1122431814.750010.197860@g44g2000cwa.googlegroups.com, "ngdbud@hotmail.com"
<ngdbud@hotmail.com> wrote:
> Yes! there is such a thing as a variable capacitor, although as
> Palindr?me said i've never seen a value above the pico farad range.
> Variable capacitors are much more common than you might think. They are
> the most common way to tune small radios. The next time you get your
> hands on a $5 radio or some price in that area open it up, i can almost
> guarentee there will be a small translucent box with a rod sticking out
> of it connected the tuneing knob. Turn the knob and look through the
> plastic box, you should see metal plates moving inside.
>
> this url will take you to a site that tells you how to build your own
> (notice it's a radio site) http://www.eham.net/articles/5217
>
> This one will take you to site that briefly describes variable
> capacitors, you'll have to scroll down almost to the bottom
> http://www.kpsec.freeuk.com/components/capac.htm
>
> This web address will take you to Froogle, google's selling site
> http://froogle.google.com/froogle?q...hl=en&lr=&rls=G
> GLG,GGLG:2005-28,GGLG:en&tab=wf&scoring=p
>
> Enjoy!
>
I haven't looked much at cheap radios lately, but a variable capacitor and
its drive is likely to be one of the more expensive components.
I recently bought some FM radios at the 99¢ store. It uses a Philips chip of
considerable complexity to provide the complicated functions using digital
techniques. This includes a variable if strip! Performance is not bad. Its
biggest drawback is that it steps through the band.
Bill
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