Michell GyroOrbe Pabst AC Motor Power Supply

A much cheaper 48V SMPS could be used to make this six component design work without any functional effect if you want to cut costs.https://uploads.tapatalk-cdn.com/202...654ca7ca0e.jpghttps://uploads.tapatalk-cdn.com/202...f91f794158.jpg

Point of note. I got the phase shift correct merely by dropping the voltage to the value you see on the scope plot. The 22V is the value the Michell dude told me so no surprise maybe.

Pabst motor winding impedances were 51 & 46 Ohms.

What I still don't really understand is why the cheap Michell PS had the 22uF cap in parallel with the transformer outputs. In this solution, the cap is in series with one output. Placing it in parallel did drive the motor super mega slow with no visible phase shift on the scope (but there must have been a tinsy bit).

Grok just fed me something about the current having the phase shift in the Michell design, rather than the voltage. Read like BS to me.

The AD9833 should give 0.0007 WRMS wow & flutter i.e. well within the ultra high end audiophile range, according to Grok.

The Owon scope suggests this isn't the case, but Grok thinks it is possibly the scope misleading me. Or maybe the PGA creates artifacts that confuse the scope. Or the TPA3255.

My gut says it's the scope. I know it's not the TPA3255 as I saw the same thing on the AD9833 output via the PGA and via VOUT (not amplified).

TBH I could spend forever looking into it and still not be 100% sure. But I am fairly certain. With the results I do see, it is still very good indeed. So I will just try listening to it.

Also, I will have a look at any harmonics that could cause rumble using the scopes FFT function. But the motor seems to be running ultra smoothly so I don't expect much of significance.

Well I can't see any trace of harmonics using the OWON VDS 1022I scope FFT function - just the fundamental.

Get something better I can't recommend it.

That's not to say that it is zero, the scope just doesn't appear to be good enough to detect any.

Decades ago I realise I was massively spoilt with some amazing Hewlett Packard scopes and logic analysers. Wish I had one here.

I declare Badman Phasinator development terminated.

Source code. Very simple.

TBH there should be enough here to make one quite easily, so I will leave it at this. Just ask an AI if you get stuck.

Anyone has permission to use this even for commercial purposes.


https://uploads.tapatalk-cdn.com/202...2929a7e00e.jpg

On the AD9833 board connect:

FSY to pin 10
CLK to pin 13
DAT to pin 11
CS to pin 9

on the Arduino board.

Few points worth making, I feel.

The SMPS, Arduino and amp module all have LEDs. This leads to a very nice red glow coming out of the case vent at night, much like it was running a load of tubes inside. Though it's more red than orange.

I think Firebottle used these cases for phono stages. They are nice. It doesn't look out of place on top of a what was once a £10K Luxman power amp. That's not where it will ultimately live, BTW.

https://uploads.tapatalk-cdn.com/202...40516942ce.jpg

Next up is the reality that other factors affect the platter speed and stability.

I have been using an Android app on a OnePlus 13 called RPM Speed and Wow.

When I first tried this I wasn't particularly happy. Over multiple uses speed came out at an average of about 33.26 RPM with wow around 0.18%.

Cleaning the platter, motor spindle and belt significantly improved this to an average of about what you see in the screen shot. Best case wow was 0.1%.

However, the belt is old, I am am only using one. There is still a degree of slippage, I reckon. The Gyrodec is designed to use two, so I have ordered another one. One failed a while ago. Will post the updated results.

I haven't listened to it yet as I am currently doing a loudspeaker mod on my Apogees. Should be complete on the speakers in a few days.

Grok reckons all wow figures I got even with the dirty setup would be inaudible, BTW. It's just nice to get it as good as possible.https://uploads.tapatalk-cdn.com/202...8fb4c7152e.jpg

One more thing. The amp module has two failure indication LEDs. The non-failure condition is both LEDs on, which caused me some confusion until I looked it up.

Phasinator plasma drive.https://uploads.tapatalk-cdn.com/202...3c79c419cb.jpg

That looks a lot better in real life as you move around the reflection off the slits changes with the viewing angle. Dead cool, really.

I bought a fake Michell belt for half the price on ebay. The wow performance is well dodgy and the platter now spins over speed.

Gonna run it for a few days to see if it gets better in dual or single belt mode.

A little knowledge is a dangerous thing. I wish I had a decent Technics direct drive to compare it with.