DIY 4 Phase Sinewave Generator for Turntable Motor Drive

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coolmaster

Member
Joined 2005
Another update. After I've replaced the reset device to MCP101, it wasn't so bad. But again it does randomly happen and trigger to 68hz (45rpm). I think I could have assumed the cause. 1) To power the the SG4, I took the supply from the Class D amplifier board, around 28VDC, into a LM2596 switching DC regulator set to exactly 12VDC to power the SG4. 2) My class D amp is with built in delay relay for the amp output and will on within a few seconds after power up. Now, what I observe is when power up at the panel mains switch, SG4 switches on at Standby normally. The Class D amp powers on at the same moment. Its when the relay cuts in that the SG4 can randomly go 68hz (or whatever I've preset). This is random, doesn't happen all the time, maybe once in a few days or whenever it feels like misbehaving.
What I may do later on is do a separate simple PSU with LM317 DC regulator to 12VDC, This may involve extra real estate into my existing chassis which was just nice for everything I've put inside. I could use an ordinary wall wart if I wanted to but I feel better with a lil more sophistication. I hope this cure the problem.
 
Pyramid

Pyramid

Member
Joined 2006
You could try isolating the SG4 input from the output of the SMPS: Add a 1A diode (1N4001 or similar) in series with the 12VDC line (cathode side to SG4, anode to SMPS output). Add a reservoir cap (220uFd ~ 1000uFd) from diode cathode to ground. This should filter out any glitches.
 
Pyramid

Pyramid

Member
Joined 2006
trekpilot said:
Hi,
Is it possible to use a different color LED display (green or blue) ? I am planning on using a ribbon cable and header from the board to the display. I have very limited electronics knowledge so any help would be greatly appreciated.

Thanks,
Scott
Click to expand...

Lite-On make different colors of the display; change the last character to specify the color: G= Green, Y=Yellow, B=Blue, WC=Red. Mouser and Digikey don't stock anything other than Orange (E), but Arrow apparently has Green:

https://www.arrow.com/en/products/ltc-2723g/lite-on-technology

You can use a different display from another mfr, but it has to be a 4 digit multiplex display with common cathode. The pin out from other mfrs will be different, so you need to make a "chart" to translate where each connection is made on the display.
 
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coolmaster

Member
Joined 2005
Hello, I customed my ribbon cable and connectors that I can easily buy from a Arduino hobby shop, everything I want is conveniently there. I also tried different display sizes (whatever available on the cheap but must be red color), as long as I know the pinout and its a common cathode, I experimented from half inch to 0.38" segment to see which I liked. As long as the SG4 is correctly connected to whatever display you choose, it will work nicely
 
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C

coolmaster

Member
Joined 2005
Back to my SG4 power up issue. I've replaced the reset IC, tried the series diode fix, no improvement. I also temporarily disconnected the Class D amp output. power on/off/on/off to try emulate the fault. It seems to behave right. When fix back the output to transformer, the fault returned once in 5-10 tries. Back to the drawing board, I think I've to entirely separate the power supply to SG4 with another independent power supply and possibly another new chassis. Current chassis cannot accommodate another PSU.
 
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cakyol

Member
Joined 2014
A bit late for thisthread but I have an old Ariston RD11 fitted with a Linn Valhalla board.
I am not sure whether to rebuild/fix the Valhalla or go this route. This method seems safer since Valhalla is notorious for lethal hi voltages. I would normally put a 30VA isolation txformer in front of it anyway but....

So, is there any way this whole thing is sold as a complete unit including the amp :)

Thanks
 
Pyramid

Pyramid

Member
Joined 2006
There is no kit available, you will need to assemble the SG4. There are class AB and class D amps available on e-Bay that are complete and assembled kits. If you want to avoid step up transformers and high voltage, use a low voltage (12VAC) motor.

SOTA now sells a 3 phase motor and controller that could possibly be retro fit into your table.
 
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