John,


Replace the Tungsten lamp with a variable resistor.  Adjust the variable
resistor until you obtain resonance.

However, are you sure you want to use a Wein Bridge?  The typical
operating range of this type of circuit is 5 Hz to 1 MHz.  Is this what
you want?

To calculate the frequency, use the formula:

fosc = 1/(2piRC)    - pi as in 3.142857......

where R and C are the values of the capacitors and resistors in the
lead lag network.

For the resistances in the resistive leg, the Tungsten replacing resistor
should be twice as big as the other one.

eg.    Make an oscillator with a frequency of 1 kHz.

(lead lag leg)

Use 1uF caps, thus   R = 1/(2 * pi * 1000 * 1E-6) = 159.09 ohms.  Standard
value 160 ohms.

(resistive leg)

use 10k

Rtungsten = 2 * 10K  = 20 k ohms


Following these formulas, you can get whatever freq you want.


Craig

-----Original Message-----
From: John Midgley <John.Midgley@ENORFOLK-HA.ANGLOX.NHS.UK>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Monday, March 16, 1998 8:48 AM
Subject: Ceramic Resonators



Fellow Piclisters

How do I go about connecting a *two* pin resonator to an '84? The schematics
I've seen so far show a *three* pin device, with a pin to ground. And are
external
caps required?

And while you're here, everyone who's an electronics bod will know
instinctively
how to make a Wein Bridge oscillator, but I'm a computer bod, so I don't. If
anyone could oblige with a schematic (ascii or otherwise) with values on
components, I'd be very grateful. Horowitz and Hill have an example, but
with
a miniature incandescent lamp that I can't identify. Adjustable frequency
would
be a special bonus.

Regards

John Midgley