Hi everyone, I need help to detect coins, I'm making a piggy bank. But I need to know the value of each coin. I don't want to sort the coins.
Can someone help me?

 

Possibilities -

1) Using canatilever spring loaded LVDT platform to measure weight
of coin. UP with hi res A/D. PSOC (with onchip 20 bit DelSig) + some code.

2) Image recognition of coin, maybe Raspberry PI with camera solution.

3) Thermal mass generated test by heating coin and finding step response
of its T.

4) Spectral response to light source, or reflectivity....

Just some ideas.

Regards, Dana.

 

If you allow each coin to roll downwards, within a narrow straight path, appropriately sized tubes will allow the coins to drop in the order of increasing diameter ... dimes first, pennies, nickels, and then quarters. Set up a reed switch or similar device in each tube to count individual coins. This might require some adjustment of the specific drop opening measurements, but the scheme does work ... It is commercially produced in a manual non-electronic version.
This device was manufactured as the 'Sort-n-Save Bank'.

 

Form a narrow sloping race which the coins roll down and off the end. At the location where the coins fall, position a narrow-beam light source and photo-transistor such that the light beam is broken by the falling coin. By experiment, determine the transistor off time for each coin value of interest.

 

I agree with Hymie. Height / width / total occluded area. With a broad light source such as an LED behind a piece of frosted plastic, and an unfocused photo transistor, each coin will have a distinctive shadow pattern as it passes through the light, producing a (hopefully) unique voltage output for each coin diameter.

ak

 

I agree with Hymie. Height / width / total occluded area. With a broad light source such as an LED behind a piece of frosted plastic, and an unfocused photo transistor, each coin will have a distinctive shadow pattern as it passes through the light, producing a (hopefully) unique voltage output for each coin diameter.

ak

With this method Can I avoid counting other metals as coins?

 

If whatever rolls down the coin race, and then produces the same beam-breakage signature/time signal as a genuine coin, then it will not discriminate between the two.

But for this to occur, the two coin disks would need to be the same diameter.

 

If whatever rolls down the coin race, and then produces the same beam-breakage signature/time signal as a genuine coin, then it will not discriminate between the two.

But for this to occur, the two coin disks would need to be the same diameter.

Thank you so much!

 

With this method Can I avoid counting other metals as coins?

I think that a strong permanent magnet near the coin path can change the speed the coin rolls. If so, coins of different materials roll at different speeds.

A magnet can also be used to deflect a steel coin into a reject path.

 

If you allow each coin to roll downwards, within a narrow straight path, appropriately sized tubes will allow the coins to drop in the order of increasing diameter ... dimes first, pennies, nickels, and then quarters. Set up a reed switch or similar device in each tube to count individual coins. This might require some adjustment of the specific drop opening measurements, but the scheme does work ... It is commercially produced in a manual non-electronic version.
This device was manufactured as the 'Sort-n-Save Bank'.

They can also use an LED and photo-transistor pair to detect where the coin drops and hence able to determine the coin type.