Arduino Connected to a Paper Shredder (Maplin basic model)

Hi there,
I have noticed on the forum that someone else has tried to hack into a paper shredder, but his post had no reply, I hope this will have better luck.

I am trying to control a paper shredder from Arduino, basically I only need it to go ‘on’ and ‘off’ at specific times.
Whereas this should be an easy hack indeed, it is my first time trying to play with an external device.

Please see the attached photos: the model is pretty basic and comprised of:

  • a DC motor
  • a PC board connected to:
    – an external button that allows the user to choose between (automatic, only plays when a sheet of paper is inserted in the throat; FFWD, which starts the credit card cruncher; REV which inverts the direction of the motor and hence of the blades)
    – a microswitch which is activated by a tab whenever a sheet of paper is placed in the throat of the shredder.
  • a cable that goes to mains.

I am not interested in controlling the credit card shredder, but only the blades which shred the paper.

At the moment I can see a few options to do that:

  1. Connect a solenoid which triggers the microswitch (probably not an elegant solution, but could work)
  2. Connect the DC motor to the Arduino, bypassing the PC board (should I contemplate using a transistor in this case?
  3. Bypass the microswitch and connect the Arduino to the PC Board where the switch is connected to, but how would I do this exactly I still need to find out.

On the back of the shredder it reads:
Input 230VAC
50Hz 0.7A 180W
1 min on/40 min off

Many thanks in advance for your help.

Best wishes

SHRED_04.jpg

SHRED_08.jpg

SHRED_07.jpg

Of all of the methods you listed bypassing the microswitch would seem to be the simplest. Place a relay across those terminals and your Arduino could easily make and break that contact.

You could also drive the motor yourself. Doing that would give you speed and direction control from the Arduino. A transistor will not cut it for controlling the motor. At the very least I would suggest a mosfet, but a full on motor controller might be a good idea given that this is likely a fairly large motor.

One more idea. You could rig the shredder to alwase run when it has power and use one of these:

https://www.sparkfun.com/products/10747 to controll the 120VAC to the shredder itself.

Oh, and please by carefull with your fingers; they don't grow back.

Thanks! I had a look at the Powerswitch Tail 2, pretty useful, yes I could rig the shredder to make it work continuously, probably blocking the microswitch on the 'on' (pressed) position; pretty good invention, they sella version for the EU too: http://www.powerswitchtail.com/Pages/PSTIIU.aspx It takes some time to have it shipped to the UK, I might have to go for another option (for this time, as I really like the Powerswitch Tail)

About the relay, how should I connect it? By terminals. do you mean the terminals that connect the PCBoard to the microswitch? I guess I will have to carefully choose one according to the current running on the circuit?

To control the motor I was thinking about using an LD293D chip or similar, and then power the motor with the existant power cable connected to the board, but not to the Arduino. do you think this could work?

Many thanks for your help!

F

XD and yes… I will look after the fingers :smiley: although the blades are pretty harmless, they are just dented discs, not really blades, that could also be an additional upgrade I should do to the shredder at some point.

Yes,

The LD293D looks like a good choice. The only thing I would watch is the current, as it looks like that part caps out at 600mA, but it would probably be fine. The 293(no D) looks like it goes up to 1A, so you might look into that also.

I would guess that to make the shredder run you would need to short the two solder pads that lead to the microswitch. You could solder two wires to these pads and then connect them to the relay so that when power is applied the relay shorts across where the switch would. Finding a 1-2 A relay shouldn't be too hard, but any of these ways should work out fine.

Good luck.

Thanks for the advice! Relay always seems to be coming up as the magic word in the last days :) I have to study them a bit, but it's definitively worth giving it a go! Many thanks for the help, I will send an update re my progress!

Best

Is there no optical sensor you could use to control it?

Most have a make/break beam sensor to detect when an object is placed in the schreddar path to provide a signal to turn off/on the blade motor?

Hi, this specific model has a little dent that can be moved whenever a new sheet enters the throat of the shredder. You can see it in one of the pics posted, it looks like one of the dents that drive the paper towards the blades. Except that by moving it activates a microswitch.