Yes; see the OP at this thread:
DIY 4 Phase Sinewave Generator for Turntable Motor Drive
DIY member Seth Hensel distributes them in the US, Ralphfcooke for the ROW.
An amplifier is of course not an "SMPS" (switched mode power supply), you can power an amplifier with an SMPS, which can be anything you like. As this amplifier and its power supply is powering a measly ~ 3W motor load, any small amp and 60Hz wall wart can work. As long as the HF noise from whatever SMPS and/or class-D amplifier does not radiate or conduct noise it should be OK, and not find its way back to the very low level of MM/MC input, which commonly have HF filters.
There are plenty of class-D "TPA3116D2" amps on Amazon for few bucks that will be more than able and handle this, and much more.
There are plenty of class-D "TPA3116D2" amps on Amazon for few bucks that will be more than able and handle this, and much more.
I built my SG4 originally to power the mains level 2 phase Hurst motor on my AR-XB turntable. I have since added a Schiit Sol to my rack, which has a 16VAC Hurst motor. So now I want to leverage one SG4 to power both turntables, not necessarily at the same time, I would switch the outputs.
The SG4 feeds a 8K2/1K8 voltage divider resulting in .454v into the TDA7492. The TDA7492 then feeds 2 Amgis L01-6362 xformers 90 out of phase for a 120VAC output on each motor phase. The TDA7492 outputs 14.97VAC/channel without a load.
My question is, can I simply change the voltage divider to 7K5/1K8 achieve the 16VAC I need through the TDA7492 and power the Schiit Sol motor directly off the output of the TDA7492? Does the TDA7492 then need a .22uF cap across the outputs to filter out HF noise? What else do I need to be considering?
The SG4 feeds a 8K2/1K8 voltage divider resulting in .454v into the TDA7492. The TDA7492 then feeds 2 Amgis L01-6362 xformers 90 out of phase for a 120VAC output on each motor phase. The TDA7492 outputs 14.97VAC/channel without a load.
My question is, can I simply change the voltage divider to 7K5/1K8 achieve the 16VAC I need through the TDA7492 and power the Schiit Sol motor directly off the output of the TDA7492? Does the TDA7492 then need a .22uF cap across the outputs to filter out HF noise? What else do I need to be considering?
If you are powering the TDA7492 from a regulated 24VDC supply, you should be able to achieve 16VAC in bridge mode. The pre-made amps will have a LPF on them, but they are designed to pass 20kHz, so you might get better filtering by increasing the caps in the filter. The switching freq of the 7492 is ~300kHz, so you don't need a real steep filter; the PCB most likely has a simple 2 pole LC filter on it.
You may need to look at the DC resistance of the 16V motor; the 7492 does not like to see extremely low DC resistance at start up and the protection circuitry is very sensitive. If it shuts down, you may need to add a small series resistor between the 7492 and the motor windings.
You may need to look at the DC resistance of the 16V motor; the 7492 does not like to see extremely low DC resistance at start up and the protection circuitry is very sensitive. If it shuts down, you may need to add a small series resistor between the 7492 and the motor windings.
I’m catching on, thanks! Since I already have an operational SG4 setup powering my AR turntable, I ordered another TDA7492 to play around with. I’ll get that one to work with the 16VAC motor, then I’ll update my functional SG4 setup to switch between 16 and 120 vac.
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I bought another amp and after some experimentation achieved just under 16v out @1.01v/60hz input. I used 8ohm load resistors on each channel out. Next step is to replace the load resistors with the motor. Once I have that setup functioning well, I will reconfigure my completed SG4/TDA7492 to toggle between 120vac for my AR turntable and 16VAC for my Schiit Sol turntable.
Appreciate the help here - Thank you!
Appreciate the help here - Thank you!
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That should work fine, with one caveat; the optimum phase settings for the two motors may not be the same.
You could chose to optimise for one, and put up with a little more vibration in the other, or to find a happy medium,
with neither perfect, but both close enough for practical purposes.
You could chose to optimise for one, and put up with a little more vibration in the other, or to find a happy medium,
with neither perfect, but both close enough for practical purposes.
I am bringing this somewhat dormant thread back to life to ask a question about which amplifier would be the best to use. I have an SG4 board and all of the parts for it from a few years ago and will build it soon. From reading over this thread, I believe the recommended transformers to use are the AMGIS. This is for a Linn LP12 so I will need two of them for 2 phase and I have found them at Digi-Key. The question I have is which amplifier would be the best. I have found a TDA7492 based amp at Parts Express, a TPA3116 based amp at PE, and a TDA7498 based amp on Ebay from a guy in San Fransisco (I am in the US also.) They are all close enough in price so as not to make a difference. Any suggestions? Your thoughts would be greatly appreciated.
Ken
Ken