Hello everyone,
I'd like to introduce you to a project that I've been working on since around 2011 - admittedly with longer breaks in between. It is a turntable speedbox (also called motor controller) and is called "MagicQuartz". I had already touched on the project many years ago in another thread here (https://www.diyaudio.com/community/threads/magicquartz-unit.281106/), but I had subsequently paused development due to various other projects. I've been actively working on it again since 2021.
The project comprises a firmware with extensive documentation and an open-source "blueprint" hardware design, called the "MagicQuartz TechDemo". The firmware is very flexible and runs on the TechDemo or any simply Arduino board. For the latter, you do not even need to have a display -- you can also interact with the firmware over a serial line from a computer. The hardware design comprises a PCB and a 3D-printable enclosure. I think it is very DIY-friendly.
This speedbox is essentially a true sine wave inverter based on a class D audio amplifier and a toroidal transformer to boost the voltage. The speed of the turntable is controlled by changing the AC frequency generated. This enables electronic switching between standard disc speeds (16, 33, 45 and 78 rpm) and real-time speed correction using an optical sensor. Note that this approach only works on turntables with an AC motor. In addition, the firmware support a special automatic voltage reduction, which can significantly reduce motor noise in some turntables (in my opinion, this is even more striking than the speed regulation).
Some pictures (OpenSCAD renderings) of the MagicQuartz TechDemo:
And here are two YouTube videos where I introduce the project in detail:
Hardware-Design: https://github.com/sebmate/MagicQuartz-TechDemo
Firmware: https://www.mate-labs.de/magicquartz/
Final note / disclosure: I originally wanted to commercialize the project. However, due to the (unfortunately!) very low demand and the high level of bureaucracy here in Germany, this is currently on hold. That's why everything is free at the moment.
Would be delighted to hear your feedback!
Sebastian
I'd like to introduce you to a project that I've been working on since around 2011 - admittedly with longer breaks in between. It is a turntable speedbox (also called motor controller) and is called "MagicQuartz". I had already touched on the project many years ago in another thread here (https://www.diyaudio.com/community/threads/magicquartz-unit.281106/), but I had subsequently paused development due to various other projects. I've been actively working on it again since 2021.
The project comprises a firmware with extensive documentation and an open-source "blueprint" hardware design, called the "MagicQuartz TechDemo". The firmware is very flexible and runs on the TechDemo or any simply Arduino board. For the latter, you do not even need to have a display -- you can also interact with the firmware over a serial line from a computer. The hardware design comprises a PCB and a 3D-printable enclosure. I think it is very DIY-friendly.
This speedbox is essentially a true sine wave inverter based on a class D audio amplifier and a toroidal transformer to boost the voltage. The speed of the turntable is controlled by changing the AC frequency generated. This enables electronic switching between standard disc speeds (16, 33, 45 and 78 rpm) and real-time speed correction using an optical sensor. Note that this approach only works on turntables with an AC motor. In addition, the firmware support a special automatic voltage reduction, which can significantly reduce motor noise in some turntables (in my opinion, this is even more striking than the speed regulation).
Some pictures (OpenSCAD renderings) of the MagicQuartz TechDemo:
And here are two YouTube videos where I introduce the project in detail:
Hardware-Design: https://github.com/sebmate/MagicQuartz-TechDemo
Firmware: https://www.mate-labs.de/magicquartz/
Final note / disclosure: I originally wanted to commercialize the project. However, due to the (unfortunately!) very low demand and the high level of bureaucracy here in Germany, this is currently on hold. That's why everything is free at the moment.
Would be delighted to hear your feedback!
Sebastian