Why not include the transformer within a negative feedback loop, to reduce any distortion it may introduce
What transformer?
I don't know. I'll just get a reputable one from a reputable manufacturer, and I've been sold ones that weren't, a little oversized, and hope for the best. We're looking for practical solutions here, not sci-fi stuff.
Why not...
I've thought about that....
I don't know. I'll just get a reputable one from a reputable manufacturer, and I've been sold ones that weren't, a little oversized, and hope for the best. We're looking for practical solutions here, not sci-fi stuff.
Why not...
I've thought about that....
Well then I'd suggest that you start by picking the motor, then the transformer, power supply, amplifier and so on ...
Well i am not so much in the mechanics but i see it as if you have two mechanical low pass filters. One through the weight of the motor rotor itself and the other via the drive belt and the weight of the turntable. And you have very much the possibility of increasing the rumble distance by reducing the drive voltage for the motor when it has the correct speed. So it is a lot of room for calculations.
But i would not use a 60Hz motor.
A phase locked motor with a very good reference frequency just as all good video recorders had in the old ages will work more precise.
And the motor should be driven by a relative high frequency or DC.
But i would not use a 60Hz motor.
A phase locked motor with a very good reference frequency just as all good video recorders had in the old ages will work more precise.
And the motor should be driven by a relative high frequency or DC.
Yes, it is not the "purity" of the sinewave that governs torque ripple but the moment of inertia of the motor and the connected mechanical load. Besides, the electrical time constant (inductance etc.) of the motor (though not dominant) also contributes to some "filtering".
Torque ripple depends only on the driving waveform and the shape of the poles. The torque ripple is then low-pass-filtered by the moment of inertia of the combined load to give a speed ripple. Adding more mass to load will reduce speed ripple but not by changing the torque ripple.
Disagree, torque and torque ripple are direct result of the current waveform while the voltage waveform could still be far from sinusoidal like PWM etc. Many drives do not use filters on the PWM but still end up getting a fairly sinusoidal current through the windings. This is more important than the voltage purity as the spatial flux distribution inside the motor is generally kept sinusoidal from the factory / manufacturing.
Yes, agreed, sorry it's the speed ripple, you're right.
T_e - T_load = J dw / dt
The torque ripple is entirely within the LHS of the above equation which is then filtered to give the speed / platter ripple which manifests itself as wow /flutter in the audio.
I picked up a cheap VIZ WR-550B function generator so i can learn to use one properly. I hooked it up to my scope and noticed some distortion on the output that I would like to eliminate if possible. My primary concern is the distorted shape of the sine wave and the two ripples at 1 MHz - it's similar at lower frequencies but the distortion isn't quite as pronounced. Square and triangle (at 10kHz) look pretty good, but have some overshoot at the peaks. Any thoughts on what to look at? I tested the caps in circuit with a DER DE-5000 and they appear to be good for dissipation and ESR. The only thing i noticed on the board is that Q5 appears to have some rust at the base . . . doesn't seem like that would cause a problem, though.