The Arrow Turntable

Welcome to the shiny world of Vinyl !
After coming across some DIY efforts at building turntables, I too decided to give it a try…

I went for an all aluminium construction and a decidedly “mechanical” look. The frame consists of 2 aluminium sheets strongly bolted together, and the platter is a “sandwich” of aluminium-acrylate-aluminium epoxyed together for some vibration dampening.

For the drive I went for what I believe to be an original path. A bipolar stepper motor drives the platter through a toothed belt (to prevent slippage) at a 3:1 ratio.

Typically, steppers are not known for a smooth motion which is absolutely critical here. However, the stepper is driven by a special purpose Toshiba chip that generates two “pseudo” sinuswaves 90 degrees apart, to drive the stepper coils, thus avoiding any vibrations.
A Picaxe 28X1 controller running at 20Mhz provides the timing inputs to that chip with the required precision, both at 33 and 45 rpm.

Finally, the tonearm is a temporary affair salvaged from an old Sanyo unit. Temporary, because phase II of this project will involve building a joystick controlled linear translation tonearm… Stay tuned.

 

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About pjrebordao

Car nut, Porsche nut Works in IT to pay the bills...
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