Heat the rolls with a induction coil (eddy currents). Then scan the roll length wise with an infra red detector. The temperatures of the silver and copper coins will be different. Count the "copper" vs "silver" temperature occurrences
BFO Metal Detector will discriminate metals.
You can search for "BFO Metal Detector circuit" by google and start to test it.
one might investigate the electrical power variation when moving the roll through the electrically stimulated coil.
A silver coin (of good electrical conductivity) among ordinary copper plated coins will result in higher damping of the electrical oscillations, given lower signal amplitude.
Sorry for the bump, but - what is an easy way to set something like this up? This sounds like just the ticket, but I'm not sure how to measure 'electrical power variations...signal amplitude." Are we talking about an oscilliscope? If so, I don't own one, nor know how to operate one... but if that's the only way... 8-O I guess I could buy one and learn. I was hoping there was something simpler to set up... like some sort of simple meter?one might investigate the electrical power variation when moving the roll through the electrically stimulated coil.
A silver coin (of good electrical conductivity) among ordinary copper plated coins will result in higher damping of the electrical oscillations, given lower signal amplitude.
You've sold me on the 'thermal' vs. 'electronic' (for lack of a better term) approach.The thermal conductivity of copper and silver are 400 and 429 respectively
Heating a roll of coins in an oven (including an induction oven ) for a short while and then viewing the rolls with a suitable FLIR camera will show the silver and copper coins
The trick is to use a cheaper type of "FLIR" camera ; but perhaps the real of the self FLIR camera will be cheaper than the development cost.
That would work - but I need to do the whole stack/roll withOUT unwrapping it.In coin selector box, it discrinate coin by using physical properties. For example
- coin size
- coin weigh
- coin electromagnetic property
https://en.wikipedia.org/wiki/Silver
https://en.wikipedia.org/wiki/Copper
That's a great question - and that was my first inclination as well. After weighing several hundred rolls (and then opening them), I discovered that - with a 0.001g precision scale - it was relatively easy to detect a roll with at least one 90% coin in it, but the difference in weight between a copper-clad and a 40% silver coin was WELL within one standard deviation of the average roll weight. I actually measured some rolls that contained TWO 40% coins that weighed LESS than some all-copper-clad rolls. 8-O Those would have slipped right past if I were relying on weight alone.Could you not just weigh the entire roll of coins? If the weight equals (weight of non-silver coin)*(number of coins) then you know there are no silver coins in the roll.
Or is the partial composition of the silver coins some metal that causes the coin to weigh the same?
(Sorry if that is an obvious question to some, but I'm no expert in US coins).
Basic indeed. See my previous post. I wish it were that easy (I tried). If I were willing to let the 40% coins go (I'm not), that method would (and indeed - does) work.From the link you gave
https://en.wikipedia.org/wiki/Kennedy_half_dollar
Mass 11.34 grams
(as copper-nickel clad)
40% silver clad: 11.50 grams
90% silver: 12.50 grams g
Diameter 30.6 mm
Thickness 2.15 mm
So, the 90% silver coil has weigh more than the 40% silver coin 1 gram per coin (12.5-11.5) gram. If a roll of coin has 10 coin, it wold has a weigh different of 10 gram per roll. It's a very basic math.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?