Turntable sequencer scratches with coins


[tvst] has an interesting take on a sequencer. His design uses coins on a turn table to trigger midi events in a loop. There are four tracks available, each having its own sensor above the spinning platform. The sensors consist of an IR transmitter and receiver setup as a voltage divider. When something passes below the IR transmitter and reflects the infrared waves back up to the receiver, the output of the sensor moves to digital high. The four sensors are connected to an Arduino which is used in conjunction with ttymidi, which converts the Arduino data into midi events.

We like projects that provide a more tangible interface for the user. Coins work well for this setup. They reflect infrared enough to trigger the sensors, and they’re easy to pick up and move without upsetting the rest of the tracks. It would be great if this could be expanded to differentiate between coins (pennies versus dimes, etc.) in order to increase the resolution from four different events to eight or more. Check out the video after the break. [Read more...]



[Mike] sent in this project. It’s a robot, designed to print on wooden coins while people watch. It was built to be in the iHobby Expo 08 in Chicago. The main movement is controlled by a BASIC Stamp2, while the ink jet system is run off of a Propeller. The entire system has 4 servos, 3 stepper motors, a DC motor, a hacked breast pump, an ink jet head, and 5 IR sensors. in case you missed that, it has a breast pump. We’re assuming that’s the part that picks up the wooden nickels with suction. He states that the project was meant to be entertaining, so there are lots of superfluous and inefficient actions as you can see in the video after the break. Great job [Mike].

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5 cent tilt sensor


This is a 5 cent tilt sensor. We know it cost more than 5 cents, but it is in fact a tilt sensor that utilizes a 5 cent coin. We’ve all done quick hacks to make quick sensors for various projects. We’ve seen tons of them, from stealing springs out of pens and shoving a resistor through them for flexible contact switches, to tin foil touch sensors. This one is new to us though. The design is fairly simple, you insert 4 bits of wire to serve as contacts and the coin will make contact with only two at a time. It isn’t analog, it isn’t extremely precise, but it is super quick and easy. Thanks for sharing [ix].


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