ELECTRICAL NOISE AND CRYSTAL OSCILLATORS?

Question by Kevin: ELECTRICAL NOISE AND CRYSTAL OSCILLATORS?
everything with a crystal oscillator has the potential for electrical noise, RFI, noise pollution.

since a caluclator has one, how can the “potential” be “unlocked”
how can it (the calcu) transmit electrical noise?

can putting a radio near it help? cus it seems to be reacting to it.

Best answer:

Answer by Stephen P
Take a portable AM radio, set it between stations with the volume turned up.

Place the radio’s AM antenna (usually a ferrite bar & coil inside the top of the radio) next to the display of the calculator, press some keys on the calculator. If the radio has a telescoping rod, retract it. It is almost certainly an FM antenna and not used in the AM band.

This worked better in the good old days when calculators had LED displays, but it still worked with a cheap solar powered LCD calculator just now.

While you have the radio out, wave it around your computer, TV, CFL, and so on. A lot of appliances put out RF hash that can be found in the AM radio band ( ~ 1 megahertz)

>crystal oscillator has the potential for electrical noise

It doesn’t have to be a crystal oscillator; compact florescent lights sure don’t have crystal oscillators; I just waved my transistor radio by one and it was putting out a lot of short range interference. .

Cheap motors with bushings can put out a lot of wideband RF interference.

OK, now for a stupid story. I pulled out an old (circa 1993) transistor radio to see if this trick still worked. And indeed it still works.

Then I opened up the battery compartment. Two of the three AA batteries were “glued” together with white corrosion gunk that had leaked from one of the batteries. The batteries were marked “Best if installed by Jul 94”. I’m sure I installed them before July 1994!

Anyway, I washed the corrosion crud off the two good batteries, reinstalled them with some old battery that was laying loose with some other junk. Now my “broadband RFI detector” works even better and is ready for a few more years of stand by service…. 😎

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