The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Subject: Re: What kind cap should I choose?
Date: Fri, 1 Nov 2002 23:35:26 -0800
Organization: SCN Research of Tigard, Oregon, USA.
NNTP-Posting-Date: Sat, 2 Nov 2002 07:37:30 +0000 (UTC)
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
0.1pF - 180pF, 1% Tolerance
0402 RF Capacitor
Capacitance Stability from 1 MHz to Several GHz*
The only 0402 Device with ±1% Accuracy for Capacitors over 22pF
Silicon-based SMD RF Capacitor
* Patent Pending
"Bill Sloman" wrote in message
> "Bob Wilson" wrote in message
> > In article <firstname.lastname@example.org>, email@example.com
> > says...
> > >
> > >Hi all,
> > >
> > >I need help please. I am building a very simple transmitter. I have a
> > uH
> > >coilin in the Drain of 2n7000 (N type MOSFET) and a cap inparallel
> > the
> > >coil and the Source to ground. The Gate is pulse with an I/O of the
> > >microcontroller. Let's say that I tune the resonance frequenct at
> > >This means I have to choose 110 nF cap (F=1/2.0* PI*SQRT(LC)).
> > >I tried two different cap.
> > > I received two different signal base on the material type that I
> > >.
> > >Is it an standard cap material they select for transmitter type of
> > circuitery?
> > >
> > >If yes which kind is the best, please?
> > There is no special "transmitter" cap. All you need is a stable, low
> > cap. This is pretty basic. Use an NO0 (also known as a C0G type)
> > the frequency you are working at (which is pretty low), even an X7R type
> > will do the job.
> The recommendation for NPO parts is dubious advice. A COG ceramic
> would be admirably stable, but IIRR you can't get 110nF capacitors in COG
> ceramic. X7R capacitors are much more sensitive to temperature.
> In fact you can't get 110nF capacitors off the shelf from any supplier I
> know. Farnell stock +/-2% polyphenlene sulphide surface mount capacitors
> to 100nF, which are probably as stable as anything that is easily
> at around that value.
> The also have +/-1% metalised polypropylene film capacitors, but only up
> 47nF - you've got to buy at least five, so get your 110nF as five 22nF
> and wire them in in parallel.
> Neither polypropylene nor polyphenylene sulphide dielectrics are
> particularly lossy at 38kHz and both would seem likely to work well in the
> Bill Sloman, Nijmegen
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup