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Electronic coin dispenser Answered

I'm trying to build an electrically controlled coin dispenser (all the coins will be the same type).

I have a metal tube -just the right diameter for the coins - mounted vertically, with a piece of wood horizontally at the bottom. There is a gap between them of approx 1mm, just enough for a single coin to be visible. I've been experimenting with using a solenoid to swipe a coin from the bottom. Rather like the image here: https://www.instructables.com/answers/Petty-Coin-Bank-Design-Coin-Dispenser-What-shou/

Solenoids aren't cheap, and I was aware that the weight of the pile of coins (I'd like to be able to hold around 100) would mean it needed to be fairly powerful. In the end I bought some cheapo solenoids from ebay (around $7 each). They are rated 2A and have a hold force of 20N - this seemed a lot more powerful than I could find elsewhere for even 10 times the price. Given how cheap they are, I could even use two in parallel if I still need more power.

I'm using coins with a 20mm diameter, but after the solenoids arrived I realised they only had a 10mm stroke - obviously not enough to fully push the coin away. I've tried using the solenoid to pull a lever, but this doesn't seem to work very well.

Previously I'd also tried a stepper motor linked up to a disk with a coin-sized hold cut on it, rather like this:

https://cdn.instructables.com/F49/GK0I/H703O9VD/F49GK0IH703O9VD.RECTANGLE1.jpg

That worked pretty well but was very slow - it would take 3 or 4 seconds to dispense each coin.

So, I'm looking for a bit of advice. Would I be better off splashing out on a more expensive solenoid with a 20mm+ stroke? Am I approaching it the wrong way?


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caitlinsdad

4 years ago

Why not have a second solenoid push it the rest of the way? Mount a spring or push-up clip to the solenoid ram under the coin midway. When the coin edge passes by, it automatically catches and then you engage the soleniod. Have it shaped like a door latch which only catches one way and will retract under the next coin when it pulls back. Maybe have the exit slot or coin slanted a little bit so gravity helps shoot it out. Good luck.

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psmith37

4 years ago

Those only accept coins, then drop them through after being checked though, yes? I'd looked around places like adafruit but couldn't see anything for dispensing coins, just accepting