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Electronics => Projects, Designs, and Technical Stuff => Topic started by: drummerdimitri on February 20, 2015, 12:27:20 am

Title: Where can I find a high frequency crystal oscillator?
Post by: drummerdimitri on February 20, 2015, 12:27:20 am
I was wondering in what electronic devices I might have at home could I find a crystal oscillator in the 20 Mhz range to test my new oscilloscope's bandwidth by checking the rise time on a square wave.
Title: Re: Where can I find a high frequency crystal oscillator?
Post by: dannyf on February 20, 2015, 01:36:37 am
20 - 32Mhz crystals are fairly common.

36Mhz or 48Mhz+ ones are rare.
Title: Re: Where can I find a high frequency crystal oscillator?
Post by: TiN on February 20, 2015, 02:26:07 am
If you happen to have broken VGA card, they usually have 27MHz
Title: Re: Where can I find a high frequency crystal oscillator?
Post by: lincoln on February 20, 2015, 05:33:04 am
keep in mind not all oscillators will have a square wave out put, many have clipped sine wave. To test the bandwidth you don't necessarily need high frequency, just a fast rise time on the square wave.
Title: Re: Where can I find a high frequency crystal oscillator?
Post by: jwm_ on February 20, 2015, 05:39:38 am
I have about 100 20mhz stand alone oscillators. I can send you a couple for the cost of a stamp. Will throw in a 48mhz one too.
Title: Re: Where can I find a high frequency crystal oscillator?
Post by: tggzzz on February 20, 2015, 11:16:00 am
For checking the risetime, a crystal oscillator is unnecessary and, depending on the oscillator may be wrong.

The simplest technique is to use a 74X14 as an RC relaxation oscillator that drives one or more 74X14 or 74X04 in parallel. Good choices are NC7SZ14M5X or 74LVC1G14, which should achieve transition times of ~1ns.