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BLDC Controller

This is a controller for a new CNC machine (photo gallery) I'm working on.

2012-03-12 - status - got the firmware "stepper simulator" working right. Holds to 1/10 degree! 4000 step/rot demo on youtube



  60/120 volt DC isolated power supply for the motors. Design size: 360 watts (60v @ 6A or 120V @ 3A). Should provide the 15 VDC control power too, if it works the way I want. Hand-wound transformer, flyback design, toner transfer on single sided PCB. Based on a March 2011 Q&A article in Nuts and Volts magazine.

I rewound the two small secondaries to 9 and 10 turns, as they were not quite producing enough voltage. EMI is high enough to reset the controller board though. I got a big linear transformer that works with the primary side of the supply that I'm also testing.

Current status: the linear supply seems to be working OK for now, so no further power supply work is planned at the moment.

The main driver board uses an 80 MHz RX/62T microcontroller (center) and an FNB41560 three-phase driver chip (right). Interfaces include:

Full connector pinout documentation (mostly for my own reference)

The board also has an RGB status LED, current sensors for each motor phase, and motor voltage monitoring.


Note: no support whatsoever is offered for these design files; use at your own risk!


Shown 2X actual size

Click image for schematic (pdf)

Shown actual size

bldc top paste gerber


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