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I just tried it, and the pattern doesn't "stand still" until the speed is -way- above 80. Neither Edison nor anybody else was using strobe discs at that time. Edison didn't even have a 60Hz line at the Lab or factories - they generated their own DC. The pattern is only a decoration.

ps - Timed it twice, with 2 different Edison records: 89rpm .

+1 to Edisone.

Some time ago, there was a discussion about this on an email list. It was right around 90 RPM before the "strobe" effect worked. I can remember trying it then, but just for kicks I tried it again on my modern setup and it doesn't work.

Sean

fran604g wrote:

pughphonos wrote:Fran, VT is right; I've read that in many sources also (re. that pattern not being a strobe pattern).

What I ended up doing is buying off E-bay (for a whopping $15) one of those hand-held laser tachometers, and they work great! You just put a small piece of reflective tape on the side of the turntable, direct the laser point onto the turntable side, and the tachometer will show the RPM in its screen. I'm really, really obsessive about correct speeds, so the tachometer has been a real blessing. Counting turntable revolutions with a watch is inaccurate to the point of being useless--whereas the tachometer will give you a decimal reading (e.g. 79.7, 80.3, etc.).

Ralph

That sounds interesting, thanks, Ralph.

I have several timing discs for my standard turntables, I wonder if anyone ever created one for 80 RPM's? I like using them.

Fran

The strobe for 80 rpm will have 90 hash marks. Cliff

OrthoSean wrote:+1 to Edisone.

Some time ago, there was a discussion about this on an email list. It was right around 90 RPM before the "strobe" effect worked. I can remember trying it then, but just for kicks I tried it again on my modern setup and it doesn't work.

Sean

It works fine if you like Billy Munchkin ... or Munchkin Kellner & his Dinner Music for Chipmunks Ensemble.

Cliff is right. 90 marks around the circle stands
still at 80 rpm.

Here's the general boiled down formula for it:

The total number of marks around the circle
equals 7200 divided by the RPM.

So for 80 RPM, that ends up as 7200/80 = 90 marks.

Why is it this way?

This is due to the fact that at an alternating current power frequency of 60 cycles per second, the fluorescent or neon lamp goes dark 120 times each second. It also turns on 120 times each second, and so can be thought of as a flashing light which flashes 120 times each second. This is because for each complete cycle of alternating
current sine wave, there are two peaks and two zero-crossings.

120 flashes per second then, times 60 seconds = 7200
flashes per minute.

If we want each mark to end up at the exact spot where
the previous mark was on the previous flash, we must
make sure that the distance traveled by the mark
corresponds with the time between flashes.

This is what creates the illusion that the marks
"stand still".

So, if you live in a country where the powerline
frequency is 50 cycles instead of 60, then
you'd use 100 flashes per second times 60, which
comes to 6000. In that case the total marks equal
6000/RPM so for 80 RPM in England, it would be 75 marks.

This can be taken even one step farther by calculating
the degrees between marks so you can lay it out yourself
and make your own. 360/90 = 4, so it's 4 degrees between
marks for 80 RPM using 60 cycles.

I use my 160 RPM strobe disk all the time for my
C-250 DD machine. It has marks every 8 degrees, for
a total of 45 marks.

But it also works fine for 80 RPM as well, it lights
them up midway through their 8 degree angular displacement on the DD machine, making them appear
to be 4 degrees apart, not the full 8 degrees such
as when turning 160 RPM on the Edison cylinder machine.

Pretty amazing that even long before 60 cycle power
and strobe disks and all of this, Mr. Edison designed
those cylinder machines to run at 160 RPM and the
DD machines at 80 RPM, and so he saved me the trouble
of even having to make an 80 RPM strobe disk. I just use
the 160 and it works fine! Edison did things that
make sense.

Chuck

Chuck wrote: Pretty amazing that even long before 60 cycle power
and strobe disks and all of this, Mr. Edison designed
those cylinder machines to run at 160 RPM and the
DD machines at 80 RPM, and so he saved me the trouble
of even having to make an 80 RPM strobe disk. I just use
the 160 and it works fine! Edison did things that
make sense.

Chuck

With all respect to Mr. Edison, I think that his engineers (such as Weber, Aiken, Conable, etc.) deserve the lion's share of the credit for this.

George P.

Another important note I'd like to point out:

When the reproducer isn't on the record and the feed isn't engaged, the turntable rotates at significantly higher RPMs. When timing your turntable, you NEED to have the reproducer lowered into playing position, on a record, with the feed engaged to accurately time it. In order to do this operation, you might want to cut down the strobe wheel I posted to the 80 RPM circumference so that it doesn't interfere with the reproducer when it travels toward the spindle on the record in step no. 7.

The process I used to time my Chippendale was:

1)Wind motor as you normally would for playback
2)Place strobe wheel on spindle (no record) and start the turntable with the reproducer UP (feed NOT engaged).
3)When the turntable is up to full speed, check the strobe wheel RPMs with the designated 80 RPM marks using a 60Hz incandescent light source, an ordinary table lamp in close proximity works fine.
4)Adjust RPMs with turntable speed control knob so that the 80 RPM marks appear to be stationary.
5)Stop turntable and remove strobe wheel from spindle.
6)Place a record on the turntable, place the strobe wheel on top of the record aligning the center hole of the strobe wheel with the spindle or the center of the record (the spindle doesn't protrude from the record enough for the strobe wheel to contact the spindle)
7)Start turntable, place reproducer in position over record and engage feed as you would for normal playback.
8)Check RPMs a second time and correct rotation speed to 80 RPMs.

The reason I use the extra steps without the record in place is so folks can see for themselves the increase in RPMs without the feed and reproducer engaged with a record for playback.

By the way, some probably think I'm nuts for doing it this way and I'm sure there are more precise and simpler methods (like a handheld RPM meter, I have an APP for that!) but the fun is in doing it old school...the way someone really high-tech could have figured out to do nearly a century ago.

Fran

fran604g wrote:Another important note I'd like to point out:

When the reproducer isn't on the record and the feed isn't engaged, the turntable rotates at significantly higher RPMs.

I'm concerned about this comment, Fran, because in my experience, engaging the reproducer should not affect the speed. If it does, something isn't adjusted and/or lubricated properly. I currently have a C-150, a B-19, and a C-19 in the house. I have tested and confirmed that all 3 run at the same speed whether the reproducer is up or down. All 3 of these have been serviced and adjusted within the last 2-3 years. Perhaps your motor needs a good cleaning and re-lube? I'd also check that your horn is set up correctly as described in the motor manual available on the board. I'll also be happy to answer any questions you have.

Cheers,
Kevin

@Kevin: I agree load shouldn't have an effect on speed (except at the moment the load is applied) but things don't always seem to work the way they are supposed to. That's why I always set speed under load on my machines - to lessen the chance of this happening. I also don't use my machines a lot, therefore I'm not as exacting about lubrication and adjustment as you may be.

@Fran: I love my tach. I've been using strobe discs since somewhere around 1960 both for myself and my job as an Audiovisual Equipment Technician. For me the cheap digital readout tachometer is wonderful to have. Not only is it not limited to two to four speeds, but it gives you the actual speed so you know where you stand instead of whether the speed is correct or not. The disadvantage of the tach is that you can't see "creep" because your readings are "snapshots" rather than continuous observation. One unexpected problem with strobes came along when electronic ballasts came into use for fluorescent lighting. These operate at a high frequency rather than 50 or 60 Hz. This high frequency operation renders a strobe useless. No longer could you depend on bench or room lighting to set speed. It was now necessary to have a neon lamp in your tool kit whereas it had previously been an option.
I'm not attempting to show any disrespect to you or anyone else who prefers older methods. It's just that I and probably others who worked with them for years welcome the new methods which would have made our daily work so much easier and accurate. So, enjoy your strobe disc if that's what you prefer to use. We are a diverse group here and I see that as a very good thing.

Jim

Great conversation on this topic. However, the Edison strobe when played just beyond the 78 rpm postion at 80rpms stabilizes when played on my Bogen 1960s turntable. Is it because of the fluorescent lighting above my turntable that causes the edison label to strobe differently compared to a regular light bulb? Or in today's world with all of us using the mercury bulbs does this cause the strobes to strobe differently?