coin operated? ideas?

[rhonald]

hi guys,

i have an idea about coin operated water dispensers and tried to search everywhere for a circuit that could help me on my project. im planning to use 555 timer and 4510 bcd counters though i havent tested it yet id like to ask for some of you opinions. the main idea is to have a slot for the coin. after inserting a specified amount it will automatically dispense water. it will be very greatful to hear from you guys. thanks in advance.

 

[Marks256]

Well, this may be tricky. You could weigh the coins, and have a microcontroller calculate the weight variance. Or you could measure the height of the coins. Not to be rude, but shouldn't water be free?

 

[dknguyen]

Are you saying no one pays your water bills? Perhaps you should ask your parents.

I'm not quite sure if they sort coins through a mechanical or electronic process. You could use through beams, or hall effect sensors for ferritic coins. But to know what coin was put in? Maybe google or howstuffworks.com knows.

 

[HarveyH42]

Well, first there are already coin operated filtered water dispensers... Hope this wasn't a commercial business idea.

Having had some recent experience in the coin operated field, I can say the sorting/rejection is mostly mechanical. The coins roll down a pathway and sorted by size. Couple of weeks ago, three japanese slot machines were dumped off on me. I just finished converting one to accept quarters. Haven't check to see if I defeated it's ability to reject other coins, but it wasn't a concern. It origional took 30mm tokens (half dollar size). I found out buying tokens would cost about 20 cents each with shipping...

An opto-interupter detects a valid coin. I'm not sure if it would be worth time and money trying to build something like in these machines at home, unless you have some serious shop tools. Coin accepters didn't seem too expensive when I was searching for documentation and tokens for the slots.

Personally, I think bottled/filter water is a huge scam. If the tap water is really that bad, people should get it fixed. If you have a well, get your own filter system, at $1.00 for a 20 ounce bottle mostly likely pay for itself first year...

 

[rhonald]

thanks for your ideas. i agree about the sorting of coins would definitely be mechanical. what im looking for is the circuit for the main process. its actually a thesis solution for the purified water refiling stations. after the coin is inserted a signal will be send to the circuit and it will open the valve for water to pour out and stop.

 

[Tarsil]

thanks for your ideas. i agree about the sorting of coins would definitely be mechanical. what im looking for is the circuit for the main process. its actually a thesis solution for the purified water refiling stations. after the coin is inserted a signal will be send to the circuit and it will open the valve for water to pour out and stop.

Limit the size of the slot's "Hole". for sorting coins. Use a bright LED an a photoresistor.The coin drops, the photoresistor is bloked for a moment and, using a triger, sends an impuls to the counter.
Use a comparator (like LM339)

 

[Marks256]

We used to own a mechanical coin sorting machine. As a matter of fact, i think it is still out in my Dad's shed. Any ways, it too had slots on a long hopper. It then had slots in the hopper for quarters, nickles, dimes, and pennies. It also had an electric motor on it, but this was only so it could the coins from a bin. The hopper/slot setup was setup so it would drop the small coins first, and then the big coins last. There was a problem with this setup, though. Sometimes the little coins would "jump" their hole, and end up in a different coin bin.
If you go with this method, then make sure you get ALL of the bugs out of the system. People won't want to use your dispenser if it is defective. I would have to second the optical switch idea. They are cheap, easy to interface, and they are very small and light weight.

 

[HarveyH42]

Personally, I wouldn't get too complicated. How many people do you really believe are going to rip off the water machine. How much do you plan to charge anyway? Quarters are your best bet, otherwise some SOB will fill your machine with nickels, and you'll loose sales or need to service the machine too often (cuts profits as well). Even if someone does pass some washers, slugs, or Canadian money, water is cheap (the fifths of the planet surface, and plenty underground...).

 

[stevez]

Is the main effort of the project supposed to be focused on the dispenser itself or the coin operation portion of the project?

 

[Marks256]

Why not use the honor system? Sure, chances are you will get ripped-off once in a while, but all you would need is a cup, and a valve!

 

[rhonald]

Originally posted by stevez
Is the main effort of the project supposed to be focused on the dispenser itself or the coin operation portion of the project?

the project focuses on counting number of coins inserted and automatically dispensing water. for example water is charged for a quarter/1 gallon of water. if the customer inserted 3 quarters the circuit will then refill a 3 gallon of water.

 

[HarveyH42]

A 4017 can be used to count 10 quarters, but 5 ought to be fine. Don't think you'll see many 5 gallon containers, let alone much bigger because of the weight. Use the 4017 outputs with different value resistors to set the duration of a 555 monostable timer, to control a solenoid valve.

The coin acceptor could be an opto-interuptor, after you figured out the mechanics of rejecting coins larger/small than a quarter, and of course canadian quarters... Would definately consider a pre-built mechanism here, check some prices. To make something on your own will take some trial and error, and good precision in construction to avoid coins from getting jammed up.

 

[rhonald]

thanks harvey ill check out the 4017 and post some feedback as soon as im finished. thanks to all of you guys. if ever you got ideas to share feel free to post up.

 

[rhonald]

i was able to check out some data for 4017 and according to what ive read it inputs a clockpulse. does your clockpulse needs to be synchronized? i mean can you trigger it manually. sorry for the question but i am just curious about it coz i cant test till tomorrow comes coz the shops are already closed. hehe thanks guys

 

[HiTech]

Just go visit a vending machine company near you and they'll likely have scads of coin mechanisms lying around. The mechs. have a micro-switch that will supply the pulse for your counter circuit, it will have adjustment screws to accurately count quarters, and it will also have a magnet to pull aside the chincy steel Canadian quarters! You can get coin mechs. that accept a combo of quarters, nickels and dimes. They might give you old ones for free or for a small amount of cash. You'd just have to figure out how to mount it to your coin operated water dispenser. Another good place to check for similar devices is at laundromats. Those Speedqueens have nice coin mechs in them and often the owner will have old spares on hand somewhere.

 

[HarveyH42]

i was able to check out some data for 4017 and according to what ive read it inputs a clockpulse. does your clockpulse needs to be synchronized? i mean can you trigger it manually. sorry for the question but i am just curious about it coz i cant test till tomorrow comes coz the shops are already closed. hehe thanks guys

You could trigger it with a simple push-button if you wanted to. Oh, you might want to put something in to reject money, after its reach the max amount, like 5-5 gallons. 4017 has a reset pin, so after the timer does its thing it will be simple enough to get everything ready for the next customer.

Can't believe the PIC word hasn't come up yet... Surprising for this forum. Anyway, you are looking maybe 15-20 parts, mostly descreets. This probably wouldn't be a bad beginner project for a microcontroller, personally I stick to what I know. Someday, I'll take the dive, but really have come across much that I really need to learn that stuff yet.

 

[Hero999]

Have you looked around?

You might be able to by pre-built coin operated moduels you can just connect to your watewr dispenser. They might not be cheap but they'll be secure and not easilly frauded.

 

[Marks256]

But building things are funner!

 

[Hero999]

Until someone rips you off and steals all your money.

 

[HarveyH42]

But building things are funner!

Edit: But building things are funnier!
*sorry, don't usually correct spelling...