60 to 50 Hz converter

[eastwestboy]

Hello,
I have 2 record players from Europe, one is pretty decent. They run on 50hz, so here in Canada with 60 Hz they run a little fast. What would be a simple way to convert to 50 Hz, the players need about 10 W, the most.

Thangx from eastwest

 

[audioguru]

A gramophone? My grandmother had one.
I haven't played mine for about 30 years.

The AC motor in your record player is made for 50Hz. It is difficult to make a 120V 50Hz power oscillator to run it at the correct speed.

 

[Mike_2545]

Heck,my 1920's era wind up phonograph has a speed control. Check there first.

 

[Willbe]

With enough inertia in the player turntable, you could feed the 60 Hz through a chopper at a precise
5/6 ths duty cycle. The power to the player is certainly low enough.

I don't know how low you can go in frequency for this AM scheme not to be noticeable. I doubt it would have to be synchronous with zero-crossings.

The output would average 25 cycles per half second.

 

[eastwestboy]

Maybe I wasn't accurate enough. One is a Philips record player from 1981. It turns synchronised with AC. The correct speed is with 50Hz, here we have 60 Hz and it turns 20% too fast. So all I need is 50 Hz and 220V. The 220V is no problem, I 'll get that with a transformer. There is no speed control on the players, also there is nothing I can do inside around the belt. No pulley change or the like is possible.
Thanks from eastwest

 

[carmusic]

they simpliest way i think is to buy a inverter from europe which produce 50hz and run it with a car battery

 

[mneary]

Why is no pulley change possible? Most entertainment equipment at that time, especially from multinational manufacturers, had that sort of option.

 

[Nigel Goodwin]

Why is no pulley change possible? Most entertainment equipment at that time, especially from multinational manufacturers, had that sort of option.

First off, changing the pulley doesn't affect the speed, second he mentioned it was belt drive anyway.

Presumably the belt is driven directly from the motor, so it's the output shaft of the motor that needs reducing - a job for a lathe?.

 

[flat5]

Yes make the drive shaft a smaller diameter. If it's brass you might just use a file on the spinning motor. I would also use a hose vacuum cleaner at the same time to pick up the filings.

Perhaps contact Philips about another shaft or motor.

 

[k7elp60]

I once had a similair problem. I used an op amp to generate a sine wave, fed it to a 20W audio amplifier and then to a 12V filament transformer secondary connected to the amplifier and the primary had the AC.

 

[crutschow]

I once had a similair problem. I used an op amp to generate a sine wave, fed it to a 20W audio amplifier and then to a 12V filament transformer secondary connected to the amplifier and the primary had the AC.

Looks like a good home-brew way to generate the 50Hz power.

For higher efficiency you could use a switching (PWM) audio amp.

If you want good frequency accuracy and stability (some audiophiles are very fussy about the turntable speed) you could use a crystal controlled sine-wave oscillator such as www.fairchildsemi.com/an/AN/AN-42025.pdf.

Willbe's idea of chopping the 60Hz to get 50Hz is interesting but I think it might generate audible noise from the motor.

 

[audioguru]

Speed variation on a record player is called "wowww and fluttter".

 

[crutschow]

Speed variation on a record player is called "wowww and fluttter".

And of course there's also "rummmble" due to imperfections in the turntable bearing.

 

[audioguru]

I can remember seeing the woofer cone in a ported enclosure wobbling all over the place due to wow, flutter and rumble from a record player.

 

[crutschow]

To think we gave that all up, along with various record hisses, scratches, groove dust noise and inner track distortion, for the featureless sound of a CD.

Makes one nostalgic.

 

[flat5]

Let's not forget record warp, scratches, groove wear, skips.

Reminds me of the old jukebox joke:

"I'm in the mood for love,
Simply because your near me,
Funny but...Funny but...Funny but...Funny but...

 

[carmusic]

or you could take a monophase motor drive and set it to 50hz output