Converting 50Hz to 60Hz???

[eclectic2k]

Originally posted by Steerpike
You can - if pressed- make up a cheap strobe with any LED, which must be powered by *full-wave rectified* AC, but NO smoothing capacitor. And a suitable current limiting resistor (1k for 12V ac.)

12V full wave rectified AC can be got from an *old* AC wall transformer/adapter, as used for portable tape recorders, answering machines, etc. You need the old style with transformer - not a modern switched-mode one.
All you do is chop out the big smoothing capacitor.

after this thread started, I was thinking exactly this. - with so many LED lights available these days... Maybe a couple of bright white LED's...

LED's should make a nice strobe as there is little to no persistence.

thinking out load: couldn't you connect two LED's anti-parallel, directly to the AC transformer? (then you just need a transformer, a couple of LED's, and a resistor?)

[Steerpike]

couldn't you connect two LED's anti-parallel, directly to the AC transformer? (then you just need a transformer, a couple of LED's, and a resistor?)

Yes indeed you could do it that way. You just need to ensure that you mix the light from the two leds - not have them pointing in different directions.

[Antripodean]

Thanks for all the suggestions. I managed to borrow a desk lamp with one of those modern fluorescent tubes All set up with the lights off and then the results - Speed at 33.3 is spot on according to the strobe disc. Speed at 45 is not so good. It is drifting backwards, counterclockwise. Guess that means it is slow?
I figure this is now moving to a how to adjust speed on my PS-X60 question. I appreciate all of your help. At least I know my ears were not playing tricks on me.

[Steerpike]

Speed at 45 is not so good. It is drifting backwards, counterclockwise. Guess that means it is slow?

How fast is it drifting?
A 45 rpm strobe disc (at 50Hz) should theoretically have 133.33333333 bars on it. But that's impossible to print (a third of a bar) so they round it off to 133 bars. That means a strobe disc is never absolutely accurate for 45rpm!
The error may seem small - 0.25%, but it's big in comparison to the accuracy a quartz pll drive can achieve.

(A 33.3333 rpm strobe disc requires exactly 180 bars, so there is no error introduced.)

[Antripodean]

It seems to drift backwards quite slowly. To give it some sense of measure, it takes over a second for one of the bars of the strobe disc to 'move' counter clock wise to the position of the next strobe bar.
I have been thinking about what you said about the number of marks (never realised this! ) and how it would not be accurate measuring 45rpm at 50Hz. Given the 33rpm speed measure is spot on then wouldn't it be highly unlikely for the 45rpm to be out?

[Steerpike]

My quartz PLL tt shows a backward drift of one bar every 4 to 5 seconds on 45 - which I believe is correct.

The Sony manual describes this corrective action:

[Antripodean]

Thanks again Steerpike! I will see what I can do