HOWTO Determine Unknown XTAL Freq

What sort of equipment? That may tell us a lot. IF TVs for example, the Color Burst Crystals are one frequency. If from say computers - there are others used. Aside from that - they're usually stamped and if you can't make them out - then a crystal tester with associated readout device would help.

I'm assuming you don't have an oscilloscope? You might be able to use one at your local high school. If just hooking up the test leads doesn't start it oscillating, get it going with a 9V battery through some safe resistance, at least 10K probably.

I don't know anything about your electronics background, but if it's an option, and you don't have access to a scope, you could build a simple circuit with a PIC microcontroller and hook the crystal to it; then program a delay loop and flash an LED with some fraction of the crystal frequency. I don't know offhand what would happen if the crystal frequency were too high for the uC though. Probably nothing destructive, but you wouldn't get the correct reading. I'd get my hands on a scope if I were going to do much messing with crystals anyway. I've seen them pretty cheap on eBay but of course the shipping charges will get you.

LMAO!!!!!!!!!!

a 4060 or two might be more convenient than a UC for this task.

Bye. Jasen

It might, especially with a solderless breadboard. The basic idea is to make the invisible visible, and how you do it depends mostly on what you have available. My preference would be to use a microcontroller, since I'm more familiar with them, and changing the delay loop is just a matter of a few lines of assembly code rather than changing wiring. The last time I used a counter chip (a 4040) was

What I don't know, not having a scope available, and never having played much if at all with crystals, if a scope probe will start a crystal oscillating by itself, or if a voltage needs to be applied across it. I just bought one on eBay so I guess I'll find out in a few days.

Yes. There are many easy and accurate ways to determine the frequency of a crystal. They require some test equipment though. Rather than have the group guess what you have and to what lengths you might be willing to go to determine the frequencies, why not give us some more information?

I assume that if you had any of the equipment that would be needed, you would not be asking the question, and I strongly suspect that your curiosity about the crystal frequencies is not commensurate with the expenditure of time and money necessary to quench it.

Correct?

Chuck

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