Great finds especially on the Rosie!
The best for my random effort to check Coinstars for many years now was a single 5 Euro cent coin - and that is it. I guess too many around here are looking too
Anyone know
how exactly the machine 'rejects' some coins and 'why' the tendency to always kick out foreign coins and often silver dimes and quarters???? Weight???? Curious people want to know.
TLDR - Coins magnetism and metal composition
I know a little after working with some vending/coin related machines over the years. Depending on how much you want to know - parts of the process is
specific to the industry,
patented by Coinstar, some is internal software beyond hardware, and some are company/trade secrets (ie not patented to prevent copycats/theft, short of stealing a machine and going through it with devices, but would be of little help due to encryption/custom ICs/etc).
The basics are the machine has a rotating internal drum that sorts off any trash (pocket lint, paper, dirt, etc) by air and gravity also doing a pre-sort of the coins size by diameter and thickness - the sound you hear of the Coinstar when in use. That is enough to reject many foreign coins as the sizes are very precise (and why some coins normally have to be put back in several times before acceptance from either wear/dirt of the coin). Even old tech can be set to
ten-thousandths of an inch if desired.
The coins then travel through more advanced sensors to detect the coins magnetism and metal composition. Which is enough to sort out the rest of the foreign coins, slugs, silver coins usually, and other rejects. The technology can be simple as that used widely in 80s
arcade machine coin mechanism to present times more sophisticated
coin mechanisms, and more likely beyond common knowledge.
Honestly if Coinstar then tests coins more thoroughly with optical sensors, cameras, perhaps weight as you said, and whatever else too I have no way of knowing.