Electronic coin dispenser

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:


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?

caitlinsdad2 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.

psmith37 (author) 2 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

For the price of a solinoid you can buy and actual programable coin acceptor.