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.
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.
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
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.
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.
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.
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.