Coin Counting Circuit

[Mastahh]

Hey,

I am trying to make a circuit that detects coins and adds the total to an arrangement of seven segment displays.

I live in the UK, so the coins i wish to use are 1p, 2p, 5p, 10p, 20p, 50p, £1 and £2.

Can you suggest anything??

Thanks a lot
=]

 

[Grossel]

Suggestion: How about posting your work so far, then we take it from there?

 

[Mastahh]

That is my problem.

I have thought about using a 4029 as the up/down counter and GENIE PICs to input pulses, but i have been advised that that would not be the most ideal situation.

Should you still want me to, i will happily post that circuit.

I am merely asking for ideas on how you would do this.

Thanks

=]

 

[Grossel]

I have thought about using a 4029 as the up/down counter and GENIE PICs to input pulses, but i have been advised that that would not be the most ideal situation.

Any reason for that? Homework? Making the counter circuit by JK-flipflops and basic logic gates? Hint: Use the features of demux to control up/down sequenze.

Anyway, If you go for the 4029 solution, you need the datasheet here.

 

[Mastahh]

Its more of a project that i am doing... An Electronic Piggy Bank

4029 is not guaranteed, just more of an idea.
However, i was told that it may not be the best idea.

I have tried the flip flop and logic gates connection to the 4029 circuit.
It counts up in ones and down in ones, but that is great for only 1 pence coins.

Im from UK so i need pulses for 2p, 5p, 10p, 20p, 50p, £1 [100p], £2 [200p]

Each 'p' is a penny value and a pulse in my circuit.

Do you have any recommendations?

Thanks
=]

 

[blueroomelectronics]

I'd go with a microcontroller, it's going to take a fair amount of logic to sum up those coins and display them.

 

[Boncuk]

Hi,

I can only see the possibility to make different slots for different coins.

Vending machines accept different coins but I guess the logic involved with it is not just a slot with a micro switch or something else (photodiode) triggering the counter.

May be you have the chance to have a look at the electromechanical part of a slot machine when it is being maintained and have the logic explained by the maintenance personnel.

Slot machines in Germany accept 50C, 1 EURO and 2 EURO, all different in diameter, width and weight.

Yet better, try to get the receptacle of an outdated machine free and modify it according to your needs.

Boncuk

 

[KeepItSimpleStupid]

I had a little electromechanical coin counter stacker in my youth. When you inserted a coin, it went down a ramp and had slots for the different sizes. No counting. Counting might be done by detecting the speed of the coin. For a piggy bank, this would seem reasonable. You might be able to detect which slot it went inn. I believe that some coin counters detect flux with proximity sensors or a magnetic field and a hall sensor and others also make sure the coins don't have holes in them and thus reject them.

 

[ericgibbs]

hi,
Just to pad out what the OP is looking for [ from a current other thread]

For all the denominations of UK coins, the coin detector has to generate a train of pulses equal to the penny value of all the coins ie: £2 == 200 counts, which will be display the total sum of all coins inserted in pence.

He wants the detection of the coins to be done using an opto-coupler for each coin type.

He also wants the ability to use manual push switches to increment or decrement every decade of the pennies 4 decade LED display, individually as well a a global units push switch.

EDIT;
The output of the 4 decade pennies counter will clock a Genie PIC, which the OP needs to use.

 

[3lectrokid]

A device i had counted the coins and it worked by you pushing a coing through a small gap and it got bigger to the size of the coin which could be calculated with a log potentiometer. the other thing it had was a metal pad to see if it conducted electricity

it would be easiest to use a small microcontroller as all calculation can be done on 1 chip including calibration and then easily outputted on an LED display

 

[Mastahh]

Hey all,

Thanks for all your replies.

Boncuk: You said look at vending machines. I saw this video online where they exposed the inside of a vending machine on this website but i am not sure if i can reproduce the magnetic fields and LED timing to sense what coin it is.

Everyone else: Nearly everyone has stated that i should use a microcontroller in my circuit. Do you mind elaborating on this? What i mean is that how i would go about it? How would i do the calculations proposed etc?

Also, a lot of people have said that i should use different sized holes.
The attachment below is what i plan to do.

Thanks for your help!!

=]

 

[KeepItSimpleStupid]

Recently,I've learned of CPUStick™ and StickOS™ -- Embedded Systems Made Easy and www.atriatechnologies.com. Makes it easy when you can program in BASIC. The BASIC runs under DOS, so you can play with it. Search YouTube - Broadcast Yourself. for cpustick. You can interface displays as well. I'd do it in higher level language for your first project. BASIC isolates you somewhat from the archetecture of the machine.

Sensing drops through different sized holes seems easy.

For fun later on, add some area with a variable reluctance transducer or be able to experiment with a magnet and a hall effect transducer to reject magnetic coins. That would just be for giggles. Even an electromagnet to detect magnetic coins. Or you can just ignore it.

 

[Grossel]

Oh' I think I see the problem now (if µ controller is ruled out).

There is a couple of way to do this. First method I can think of is to use two simple registers (a row of d-flopflops) and a binary adder circuit. Thats just an inea, I haven't taught about how to connect them, but there sure is possible to get it done.

Second, size of the coins may pass several sensors so that the number of sencors that responds for a single coins is the same as number of pulses to counter will be. This solution I think is least realistic. It may not work as I think, but then I'm not very familiar with punds coins.

 

[KeepItSimpleStupid]

I see using a sensor for each coin. Detect the drop through the single hole.

Of, course the coins have to go through the smallest to largest size. The ramp must be steep enough no to let the coins get stuck.

 

[ericgibbs]

hi,
I would suggest before posting to this thread, you read my post #9 on this thread which outlines the OP requirements.

Its not coin detection thats the problem, the OP has a working slot system, its the counting of the value of the UK coins in pence and the need to manually control the counters U/D for all the 4 decades.

 

[Mastahh]

Expanding on what Eric said...

I have got the slots and sensors working.

My problem is that actual detection of what coin is what, and how to add these digits to the 7 segment displays.

Can you help me on this??

Thanks