Security for Newer Vending Machines

Discussion in 'Power Electronics' started by Michael Elder, May 2, 2018.

1. Michael Elder

3
1
May 2, 2018
Let me start by saying I have no degrees in anything. I am currently studying for electrical engineering in my freshman year of college.

I wanted to know how well newer vending machines prevent against newer types of attacks. I want to see if I can make a proof of concept, or learn why my idea wouldnt work. My idea is as follows:

I have a theoretical vending machine, and I want to get whatever it is out of the machine without opening it, like a normal person would. It's encased completely in metal, and the objects are protected internally until the spiral bar that most vending machines have turns to dispense it.

I wanted to know if I could use a heavy enough duty inductor or copper wire coil, if this could activate the motor that controls the spinning spiral bar.
Would it be possible to make a proof of concept of this? I understand that steel and a few other metals would absorb the energy and heat up, but if it isn't entirely steel, could enough energy get through and turn to dispense an item? I apologize for not knowing exact values, like what power specs the motor would run at. And don' worry about how much coiling or inductors I need, since I live next to an engineering building, as well as any additional parts required.
Thanks for checking me put, as this is my first post I've made so far, and thanks for taking the time to respond or at least read this far. Have a great day!

2. kellys_eye

4,277
1,146
Jun 25, 2010
Short answer is a simple 'no' - you cannot make the motors work in the fashion you mention. Longer answer - the motors require a specific voltage, current and (most likely) a switching sequence that cannot be created by 'forced induction'.

3. Michael Elder

3
1
May 2, 2018
By switching sequence, you mean a series of ramping the voltage and/or current by means via control with other more complicated circuits?

4. kellys_eye

4,277
1,146
Jun 25, 2010
They commonly use stepper motors (sometimes servo motors) which require a particular step sequence (correct order, correct voltage etc) to make it rotate in a given direction. Wrong sequence and it could rotate backwards or not at all. Sequence speed determines rotation speed.

You can drive these motors using discrete components but commonly they use specifically designed IC's that contain all the necessary drive and current-limiting circuitry.

5. Alec_t

2,759
735
Jul 7, 2015
Considering the relatively low speed at which the typical spiral rotates, there is almost certainly a reduction gearbox between the spiral and its motor drive. This means that to force the spiral to rotate you would have to overcome very high frictional torque. But as the spiral is symmetrical about its longitudinal axis and is not iteself magnetically polarised, I can't conceive of any way an external coil could cause it to rotate.

6. shrtrnd

3,701
462
Jan 15, 2010
Vending machine manufacturers specifically design their equipment to prevent field losses of their products (and cash input).
If you're trying to defeat the vending machines in your freshman dorm, buddy-up to one of the rich kids, and have him (or her) subsidize your munchies.
Most of the vending machines I see now also take credit cards. You could try a college major in an electronics field that might help you create a hack that would defeat those.
(This is meant as a joke for you engineers with little to no sense of humor)

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7. kellys_eye

4,277
1,146
Jun 25, 2010
Here in the UK we find that a 'Yorkshire screwdriver' can open most things.

Note - Yorkshire screwdriver = big f.o. hammer.

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