Vending machine

[dairin]

can anyone help me with designing of simple vending machine ??

it accepts only 5cts and 10cts coins
once the money total up to 15 cts, the dispense led will light up and waiting for consumer to press the button to dispense the product

but if the money more than 15cts, it will need to light up the change led

once the dispense button is pressed, it will need to reset all

anyone ?? i really need it for my project

 

[Agent 009]

Is your project involving Logic Design? I mean, you're using TTL chip family or so? If your project consists of using logic gates with flip-flops, you'll first need to draw a state diagram, or they call it also state graph. Then you'll build up a state table, and then you'll find out what are your flip-flops input equations... If you want that, just say so while I figure out a way to include a picture of the state diagram, cause frankly I dunno how to include pictures on MY computer in my replies. Do I have to upload them onto a Internet server before posting'em???

 

[Optikon]

can anyone help me with designing of simple vending machine ??

it accepts only 5cts and 10cts coins
once the money total up to 15 cts, the dispense led will light up and waiting for consumer to press the button to dispense the product

but if the money more than 15cts, it will need to light up the change led

once the dispense button is pressed, it will need to reset all

anyone ?? i really need it for my project

This sounds like a school assignment.
Here is what I would suggest to you: Try and work out the design yourself first and along the way, when you have problems/questions, see if others can help. Believe me, you will get MUCH MUCH more out of your assignment if you try it yourself. There are many users on here quite capable of posting a solution for you but that leaves you incapable of coming up with one yourself. If you are serious about learning digital electronics, take the time to work on this problem - Trust me.

 

[kitedude]

i did a very similar project to this a while back.

i used a basic stamp 2 to do most the work.
i used 3 7seg displays to output display.

lookit just send a mail to kitedude@kitedemon.com and i'll send you on some good pointers.

 

[Sebi]

And what is the coin sensor?

 

[kitedude]

For the coin sensor. I just used buttons to simulate coin entry.

heres some more detail.

10 product buttons and 6 coin buttons.
I used a 74c922, this uses a 4x4 matrix to provide 16 buttons. the output is in 4 bit binary fed in to a stamp.

i then used a 4 bit bus to display on out on 3 7-seg displays.
i used three 74hct4543 for each 7seg.
the 4543 takes a binary number and displys it on the 7 seg.

i also used a 74hct154 to display product release leds. i used the same data bus as for the 7segs, as i just used the enable to shut off the 7-seg

the code for the stamp is failry easy. i'l;l let you figure that out for yourself.

 

[Agent 009]

Look, I had this problem in the final exam of my Logic Design course. But It didn't use any 7-seg displays or coin sensors.. We just had to do the design, and the "real" practical part was left over. We just drew a state graph, and... As I said before... By the way, how machines senses which coin it is? I mean, the 10, 5 or 25 cents, or so??

 

[Manandp84]

This is to answer Agent 009’s question...

At first I thought that the coin would be sensed due to is size and thickness, seeing that 10 cents is thinner and smaller than 5 cents. I realized that this would allow me to put in a false coin (a peace of circular metal with the same dimensions) and still get my "candy", this is completely untrue and can't happen in today’s Vending Machines… so I decided to do some research, :idea: and found that the machines judge the coins by the size and the metallic content of the coin.

First, when the coin is inserted it rolls down a ramp and passes between two pieces of magnets. The magnetic field produced by the magnets, slows the coin to a pre-programmed speed according to is metallic content.

The coin also passes through a Laser Emitting Diode (LED), which measures the speed and diameter of the coin as it passes through the path of the laser beam and sensor, the speed and diameter is calculated by the program.
Now the program will compare the values to a pre-programmed range of values for the speed and size of a particular coin.

 

[Electric Rain]

I'm not sure if this is too... "assembled", but how about this?: **broken link removed**

Please let me know if this will work for you, no one ever does so it would be appreciated if you did so.

 

[Agent 009]

Wow, i didn't think that it was so complicated...
About the site mentioned, well it contains a lot of coin selectors, but how abt their mechanism???

 

[Agent 009]

Well... I changed my mind. @ first it looked boring (everything was for sale...) but then, it did in fact tell a little about how each selector worked.. I was just interested abt how to build such things. I repeat, I did the design in an academic course, but the building process was not even reached...