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In the Forum: Analog Playback
In the Thread: Copper Mat on a Micro Seiki Gun Metal Platter
Post Subject: Power supply regulatorPosted by Wellington on: 10/10/2017
I was asked for more information on my power supply regulator, which allows the original 100V power line (Japan) to be plugged directly into a 120V line (US), while greatly smoothing the ripple going to the motor.
I must have drawn my schematic on a piece of paper and it is now somewhere in a box. Usually I put my designs into digital format, but I must not have here. If I can locate the papers, I will provide more information later.
For now, I can show two images. One shows how I mounted an LM317T onto the underside of the chassis for heatsinking. I used an existing stand-off stud which supports the PCBs. Note that I insulated the LM317T's tab from the chassis. The other shot shows the tiny added prototype board that holds the associated components. This board is about 1.5" by 1.5". It mounts on that same stud, between two existing PCBs. You can see the red heatshrink tubing coming from below the little added board, through a Molex type connector. This connector allows me to be able to remove the PCBs for service without having to dismount the LM317T. The circuit is simple if you know the venerable LM317. The upper resistor is 249 ohms (1%) and the lower resistor is 5.49K (1%). I added two safety diodes and two small caps, per the usual LM317 design. The resistor ratio gives about 29 V out. Note the large dark blue main cap above the added board. I increased the PS capacitance dramatically to make sure that the LM317 is always getting enough input voltage to stay in regulation. I don't recall the value but it is probably about twice the original value. All other electrolytic caps were replaced with the same values.
Hope this helps. A technically-oriented person can figure it out from this.
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