Which are the cheap & more expensive way to know if there is self-oscillation ?

[kagliostro]

Assuming there is a self-oscillation on a circuit which are the more cheap and the more expensive solution to discover it ?

I'm thinking to something that can't be hear like when the self-oscillation isn't at audio frequency

how is possible to discover it for sure in the cheaper way ?

exist an expensive way to discover it, a devoted instrument, something like a frequency scanner ?

Thanks

K

[HotBluePlates]

Cheap: thinking about why the amp is not working

Expensive: oscilloscope

EDIT: Mid-price: A.M. radio tuned between stations. An oscillation in the kHz range will likely show up as a noise other than the normal static on an a.m. radio.

[kagliostro]

Hi HBP

A.M. radio tuned between stations

Very simple and ingenious !

at the moment, here in Italy, are about to be closed even the latest medium wave stations

that is something to give a taste  

K