So, an on-off switch and a mechanism to reverse the polarity of the DC current. Now that we have DC, we need to be able to get the power to the motor, to be able to turn it on and off, and be able to reverse the motor in case of jams. You can check out this Wikipedia article for more detail and some pictures. I guess this design is more popular with higher voltages. The one I got for this project is the square type. The square one has the AC come in opposite corners and the DC out of the other two corners, just like you would see in a circuit diagram. The rectangle type usually have the AC come in the center pins and the DC out of the outer pins, with the positive towards the beveled corner. It can be simply 4 diodes soldered on the circuit board, or it can be an integrated circuit taking the form of an upright rectangle with a beveled corner, or a square unit that lays flat on the board. There are 3 popular diode arrangements to make those bridges. Well, it is usually an arrangement of 4 diodes that will act like traffic cops, directing all the electrons going in one direction to one wire (the negative, normally black wire), do their loop on the circuit, and come back through another wire (the positive, normally red wire). Ok, so now I know that I need a bridge rectifier, but what is it exactly? Just remember that it's part of the AC wiring. I won't talk about it either in the following steps. If you dig a bit deeper, you can find a micro switch that cuts power to the unit if the bin is removed. Note : the actual voltage from the outlets in your home may vary. We now also know that we need a way to convert 120V AC to 120V DC.Įnter the magical world of rectifier bridges!
The fact that this is a 120V motor can be considered a good thing, since no transformer will be needed in the new circuit. The other two are blue, and from what I can tell, they are probably from a sensor of sorts, since there was an overload LED on the cover. In this case it's a 120V DC motor. Note that there are 4 wires coming out of the motor,and two of those are obviously the DC power wires since they are black and red. When taking out the motor, check for a sticker with the specs. correct me if I'm wrong, but nonetheless. I have my doubts about reversible AC motors. I of course kept the board for any salvageable components in a future project.Īpparently, this shredder came in a version with an AC motor, and a version with a DC motor. In my case, I had no clue as to what was broken, so I just removed the circuit board and cut the wires as close to the board as possible, in order to give me some room to move later on. Soldering iron and solder - recommended, but it's possible to do without.ĭremel - again, recommended, but it's possible to use other cutting tools Insulator for some connections - heat shrink, electrical tape, marettes.Ĭrazy long philips screwdriver - I used an 8 inch #2, but it was tight, so maybe a #1 would work better On-off switch - optional if your DPDT switch has an off position let's say that I hadn't quite grasped the mindset of photographing for instructables yet. The downside is that this project was done way back in February 2010, and the first steps were not documented with photos. This is my first published instructable, yay! The simple fix is to make a basic circuit that will run the motor forwards and backwards. I always wanted to get a shredder to dispose of sensitive documents, so when I stumbled on an ad for a broken shredder to give away, I jumped on the occasion!īasically, the electronics inside were shot, but the motor was in perfect working order. Here is one way to inexpensively bring a shredder into your home office!
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