ES-Speed-Box-Power [KiCad/Board1]

Contributors (1)

CW

Colin Williams

4 commits 6mo ago

License

MIT

Full License Text

MIT License

Copyright (c) 2025 Colin Williams

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
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README

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Prototype. ## Introduction: A speed controller to suit Pro-Ject Turntables with 16VAC synchronous motors (Expression 3, etc). A clone of sorts of the off the shelf line of Pro-ject "SpeedBox" devices that allows for 33RPM and 45RPM speed selection electronically instead of changing the belt/pulley beneath the turntable platter. Speed selection is controlled in software using a DDS (direct digital synthesis) IC to generate a sinusoidal waveform of the appropriate frequency (~50Hz for 33RPM, ~67 for 45RPM). An I2C header allows for an optional external OLED screen to display speed selection. An 18VDC output provides power to a Pro-Ject Phonobox. The device can be WiFi enabled to allow the speed to be controlled remotely using MQTT auto-discovery via HomeAssistant. Power to the circuit is controlled via an SSR (solid state relay) and is intended to be connected to a 12V amplifier trigger output. Thus the device has no phantom power draw and only powers the turntable when the amplifier trigger output is on. ## Project Goals: 1. Powered on when the amplifier is on/phono aux input is on. 2. Provide power to both the turntable but also an Phono Box II pre-amp. 3. I2C interface to allow connection of an OLED screen to display speed and amp volume (amp volume via Yamaha API). 4. Low profile design to fit in a small rack mountable case.