question about crystal oscillator output waveforms

MrChips

Joined Oct 2, 2009
22,101
Ok. Next question.
What are you using to power your chips?
Have you looked at the power supply rail with the scope?
Do you have 10μF electrolytic capacitor and 0.1μF ceramic capacitor across the power supply rails?
 

Thread Starter

Jidis

Joined Nov 26, 2013
13
MrChips-

It's all coming from an HP6205C bench supply. Looking at the supply now, it's pretty clean if I disconnect the two chips (7404 oscillator & 74HC14 gates), but there's quite a bit of noise added as each one is reconnected. Don't know if I'm doing things right, but it almost looks like over a half volt of ripple on the supply when they're both up and running.

I'll see what I can do with some bypass caps. Can the unused pins of those two ICs here be safely left open, or could that add noise?

Thanks!
 

Thread Starter

Jidis

Joined Nov 26, 2013
13
I did get some of that ripple down adding the bypass caps to both chips, but I'm not sure if it was just from moving jumper wires around. Unfortunately, my wave output from that crystal circuit looks roughly like it did before.
 

Thread Starter

Jidis

Joined Nov 26, 2013
13
MrChips-

I think you were onto something with the probe stuff. I disconnected and moved the probe and some wires around and it snapped into something much nicer looking (attached picture). That overshoot thing can be tamed down with the scope's filters, but I'm not sure it would matter to whatever I sent the signal to anyhow.

I guess these high frequency types don't approve of my messy workspace. :(

- Much Appreciated!
 

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