On Mon, 27 Nov 2006 02:32:43 GMT, "Farce Milverk"
wrote:


"John Fields" wrote in message
.. .
On Sun, 26 Nov 2006 17:20:03 GMT, "Farce Milverk"
wrote:

Hi,

I have 2 crystals rated at 3.57 MHz (for driving video)

One is 2 pin, and the other is a 4 pin. I have the 4 pin working, but
not
the 2 pin -

I am looking for info on how to substitute a 2 pin in place of a 4 pin.

---
For the 2 pin you must build an oscillator.

--
JF

Hi John,

Can you point me to info on why this is the case?

Thanks!

Farce


What John means is that the 4 pin device you have is an active
oscillator while the 2 pin device is simply a crystal which requires
other active components to get it to oscillate. The 4 pin oscillators
are commonly used to produce clock signals for IC devices. 2 of its
pins are simply to provide + and - power for the internal oscillator
which uses a crystal to set the frequency. The 2 pin crystal doesn't
have the oscillator part so you need to provide it.