Turntable Hack
March 19, 2012 by stefankueppers
The other week Alice and Mandy started evolving ideas around the use of Zoetropes. Mandy produced some wonderful origami birds and Alice sketched out a series of cardboard mock-ups on a wooden ‘cheese board’ turning platter. These worked nicely for some very initial sketches but would not allow filming well and the rotation speed would vary.
Alice found some great turntable hacks for Zoetrope out on the web that got us thinking: Our Zoetrope experiments needed more control and flexibility in the electronic and mechanical design aspects so rotation speed could be controlled more precisely in future design iterations.
The hacked turntable ensemble
Ok: The Public Goods Lab (i.e. myself and the kit…) got involved in its technical capacity to support this. Alice brought in her old Technics turntable and I had a go at making our own motor driven Zoetrope as a hack from it: As it turned out with her turntable the real issue was that it it did not allow placing arbitrary size objects on the platter as the Technics model was designed as a slide-out chassis so we needed to do something with it before we could use it for Zoetrope testing.
I got onto disassembling the chassis getting the rotating platter out of it with its motor. The electronics were so tied to the chassis that I decided to just fix a stepper motor on the side of the platter base and made a little Arduino controller and breadboard motor driver circuit to go with it. The driver circuit is just suing a ULN2003A chip for a quick and simple test ( That chip is a multi-transistor package so I did not have to roll my own H-bridge).
I first used a unipolar stepper [4 connections] but the circuit [I used this post from eLABZ blog ] was getting a bit hot with a floating voltage across the driver chip so I ended up reverting to a bi-polar stepper motor (still using the same circuit as above but dropping the floating voltage and this works just fine without the driver chip overheating. There are two poer supplies, one driving 5V for the Arduino board and another 12V supply for the stepper motor driver. Both were taken from an old hard disk power supply and wired into a breadboard. The circuit used has a tow small switches that let you change the stepper direction which is a nice convenience.
Arduino + Stepper driver electronics
More code hints for Arduino stepper control see the
introductory Arduino stepper control tutorials
The code can be tuned to change the speed of the stepper a little bit but this could alaso be extended with more control buttons in the circuit which we may do if we really need it.
