Punch Cards

Before the Commodore 64, the IBM PC, and even the Apple I, most computers took input data from a type of non-magnetic storage medium that is rarely used today: the punched card. These pieces of cardstock held programs, data, and pretty much everything used to run computers in the before-time. But with all of that paper floating around, how did a programmer or user keep up with everything? Enter the punch card sorter and [Ken Shirriff[‘s eloquent explanation of how these machines operate.

Card sorters work by reading information on the punched card and shuffling the cards into a series of stacks. As [Ken] explains, the cards can be run through the machine multiple times if they need to be sorted into more groups than the machine can manage during one run, using a radix sort algorithm.

The card reader that [Ken] examines in detail uses vacuum tubes and relays to handle the logical operation to handle memory and logic operations. This particular specimen is more than half a century old, rather robust, and a perfect piece for the Computer History Museum in Mountain View.

It’s always interesting to go back and examine (mostly) obsolete technology. There are often some things that get lost in the shuffle (so to speak). Even today, punched cards live on in the automation world, where it’s still an efficient way of programming various robots and other equipment. Another place that it lives on is in voting machines in jurisdictions where physical votes must be cast. Hanging chads, anyone?

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A.R.T. sorts your recyclables for you

[Yuhin Wu] wrote in to let us know about the Automated Recycling Sorter that was built with a group of classmates at the University of Toronto. They entered it the school’s student design contest and we’re happy to report that it took first place.

The angled sled has been designed to separate glass, plastic, and metal containers. The first sorting happens at the intake area. A set of moment arms are used to weed out the glass bottles. Since there are several of them in a row, a larger and heavier plastic container will not be falsely sorted and the same goes for smaller glass bottles.

With the glass out of the mix the team goes on to separate metal and plastic. An Arduino was used for this purpose. It senses an electrical disturbance caused by a metal can passing through the chute and actuates a trap door to sort it. Plastic has no effect on this sensor and slides past the trap to its own sorting bin.

Don’t miss both demo videos which we’ve included after the break.

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NXT machine sorts LEGO blocks automatically

Smart people don’t put their toys away, they build machines to do it for them. Case and point: this NXT project which can sort LEGO pieces. Just dump a bucket of random blocks in a hopper on one end of the machine. One slice at a time, these plastic pieces will be lifted onto a conveyor system made up of several different belts, which allows for separation of the parts. One block at a time, each piece enters a specially lighted chamber where they are visually identified by the NXT brick. Once it identifies the block, a carousel of plastic containers rotates to place the correct home for the block below the output shoot seen above.

So do we now have a completed LEGO circle of life? Not quite. You can build structures automatically using a 3D LEGO printer and this sorter will have no problem organizing the parts for that purpose. But we still need a LEGO machine that can tear assembled bricks apart.

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LEGO pick and place

Turn your volume down and take a look at the brick sorting robot in the video above. It’s built using LEGO and powered by four different NXT modules. It sorts differently colored bricks on the intake conveyor and places them on three output conveyors. The build is solid and was [Chris Shepherd’s] impetus for starting a blog. We appreciate the pneumatic tricks that he detailed in some of his earlier posts such as a compressor, pressure switch, and air tank system. His advice is “build, build, build” and that’s what you’d have to do to perfect a monster of this size and scope.

Color detection using an RGB LED

[Kyri] has made a simple circuit to do color detection using an RGB LED. Simply set the LED to the color you want to detect then wave the object over it. Another LED will light up if the object is the same color as the LED. The detection is done by a photo resistor. The theory is that an object will reflect more of the light that matches its surface color. She shows that this kind of detection could be useful for sorting in robotics.