What Happens When You Point a Video Camera at the Monitor That Is Displaying What The Camera Sees? Runaway Visual Echo... Technical Name is Video Feedback Loop...

The Basic Idea was written about in a Book Called Godel, Escher Bach by Douglas Hofstadter.
https://en.wikipedia.org/wiki/Video_feedback

While I was working as a clerk at Radio Shack, I Had use of all that equipment... after the store was closed... I payed with this idea and had a lot of fun...

Ham Radio... Selling Equipment at Radio Shack in the 1990s - I Met a Lot of Interesting and Obsessive People who were Amateurs.

It was Really Fun to Be Introduced to The Ham Radio Culture... a World I Had No Contact With...

Dot Dot Dot DASH DASH DASH Dot Dot Dot... SOS...  

Link to More About Ham Radio Operators...

https://gvan42.blogspot.com/2020/05/ham-radio-selling-equipment-at-radio.html