# Anyone know a simple circuit to make a signal generator using a crystal oscillator? (if possible)

#### Robert Hill

Mar 5, 2015
112
Hi all,

I salvaged two small crystal oscillators from some old electronics and i'm wondering if I can use them to create signal generators to kick out sine waves. I'm not particularly looking to power anything, just want to plug them in to the oscilloscope to see the wave.

The two I have are printed with 24.00014 and 29.4912

Any suggested reading/videos/schematics appreciated , unless it isn't really a good/possible idea to try in which case tell me that!
Ta,

#### BobK

Jan 5, 2010
7,682
If they are indeed crystal oscillators and not crystals, they will output a square wave. How many pins do these have? If 4 they are oscillators, if 2 they are crystals. If they are actually crystals, look for crystal oscillator circuits which will give you sine wave at the crystal frequency.

Bob

#### Robert Hill

Mar 5, 2015
112
They only have 2 pins so I guess they must just be crystals. I've not found anything yet online that is easy enough for me to understand. Can I just apply a voltage across them?

#### duke37

Jan 9, 2011
5,364
A picture would tell us if they are crystals or crystal oscillators.
If they are crystals putting a voltage across them will do nothing.

You will need a very good scope to look at those frequencies, 24MHz and 29.5MHz.

Probably there will be many circuits on the net. If the crystals are old or damaged they may be lazy.

I once had a boss called Robert Hill - nice chap.

May 8, 2012
4,960

#### duke37

Jan 9, 2011
5,364
Dave
"no you cannot you will damage the crystal"

Why is this? They are often run with a small voltage across them and of course pass AC when operating. They can be damaged by excess AC when used in a powerful valve oscillator.

Trevor

#### davenn

Moderator
Sep 5, 2009
14,271
Why is this? They are often run with a small voltage across them and of course pass AC when operating.

simply because it isn't the way crystals are meant to be used

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