LED lights and strobe discs don't mix!

[barnettrp21122]

I've been swapping out incandescent bulbs for the efficient LED's throughout the house, but noticed that stobe discs won't work with them. Too bad-they're the simplest way to regulate a turntable!
I have one of those laser rpm things for the cylinder machines, so I guess I'll have to start using it for the turntables. Or else, start carrying a little regular plug-in lamp around the house!
Bob

[Chuck]

It's a simple matter to make a very good little
strobe viewing lamp.

This is what I use to view strobe disks:

Parts:

1) Small neon lamp such as NE-2. or equivalent.
2) 100,000 ohm, 0.5 watt resistor.
3) A length of lamp cord with a plug on the end.

Procedure:

Connect resistor in series with lamp, and connect
this series string to the end of the cord. Solder
the joints. Insulate with electrical tape or use
heatshrink tubing for a neater job.

The neon lamp needs the resistor in series in order to keep the current low. Connecting a neon lamp directly
across the A-C powerline will destroy the lamp.

Plug it in and hold the neon lamp close to the disk
as it spins.

I also make my own strobe disks for cylinder
phonographs. Draw straight lines on a blank paper
disk, the lines being 8 degrees apart. This will make
a strobe disk for 160 rpm.

The secret of it is that the light source must
shut off every time the power company's A-C sine
wave crosses zero. With a 60 cycle per second
wave, this zero-crossing happens 120 times every second.

The rest of it works because as the disk spins,
it takes exactly 1/120th of a second for it to
rotate 8 degrees, when the disk is spinning at
160 rpm. It then appears to stand still.

Other speeds are workable too.
For instance, for 80 rpm, it is 4 degrees.

Bottom line, the light must blink on and off
in order to make the disk appear to stand still.

Any lamp with a filament in it is really rather
poor at being able to do this, because of the time
it takes each time it "shuts off". Filaments
take time to cool. Neon shuts off much faster,
in a few nanoseconds.

An LED could be used too, because those shut off
instantly as well. But, lord only knows that they've
got in those newfangled "LED bulbs" that change
the frequency, so that's why it doesn't work.

A neon lamp still works best, in my humble
opinion.

Chuck

[Henry]

Or you could buy one of these: http://www.amazon.com/professional-tach ... pm+counter

[Scott]

Or you could buy one of these: http://www.amazon.com/professional-tach ... pm+counter

That's a little more my speed...

[Phonofreak]

I go one of these a few years ago. They work great on both cylinder and disk machines.
Harvey Kravitz

Or you could buy one of these: http://www.amazon.com/professional-tach ... pm+counter

That's a little more my speed...

[VintageTechnologies]

The new LED bulbs won't work as practical strobe lights because their internal power supplies not only step down the voltage, but also increase the frequency from 60 Hz to minimize flicker before rectifying the current to DC. The cheap units do a poor job of DC current filtration and some people claim sensitivity to the high frequency flicker. I have seen demonstrations of a number of LED brands using an oscilloscope coupled to a photo cell. By far, the smoothest light output comes from the better Phillips bulbs.

[De Soto Frank]

LED lights are evil. EVIL, I tell you !


I was momentarily flummoxed a few years ago when I was trying to regulate the speed on a Grafonola, and I couldn't figure-out while I couldn't get the pattern to slow-down or stop... no matter what I did to the speed of the machine.

Then it dawned on me... I was working in a room under natural daylight...


I guess sunlight isn't 60 hz either...

[howardpgh]

Try this thing. It's tiny, but it works well.
https://www.tindie.com/products/bot_tho ... le-strobe/