LP12 Basik power supply
- Thread starter JMP
- Start date
It *is* very simple. The Armageddon is equally simple, once the transformer is taken into account. You only need a capacitor to supply the field coils with mains 90 deg out of phase and the motor will run. The resistor just limits the current, and you're in. Oh, the joys of synchronous motors.
martin clark
pinko bodger
The resistor doesn't actually limit the current - the high inductance and resistance of the motor does that (c. 4.7- 5H and around 10Kohm total impedance at 50Hz). These motor values dominate in calculating suitable R, C values.
So the resistor just drops the voltage appearing across the motor. Bigger resistor = lower voltage = less vibration, limited only by needing enough volts to make the turntable actually start-up.
For values, try R=4700ohms to 6800ohms, C=0.2uF. You'll see C=0.22 in many circuits, but two 0.1uF caps in parallel gives a more accurate 90degree phaseshift for the Linn motor on 50Hz mains.
As Steve says, the Armageddon only adds an isolation transformer to the basik(sic) idea.
Don't overlook RichardH's excellent article in the Reference room:
http://www.pinkfishmedia.net/forum/showthread.php?t=22291
So the resistor just drops the voltage appearing across the motor. Bigger resistor = lower voltage = less vibration, limited only by needing enough volts to make the turntable actually start-up.
For values, try R=4700ohms to 6800ohms, C=0.2uF. You'll see C=0.22 in many circuits, but two 0.1uF caps in parallel gives a more accurate 90degree phaseshift for the Linn motor on 50Hz mains.
As Steve says, the Armageddon only adds an isolation transformer to the basik(sic) idea.
Don't overlook RichardH's excellent article in the Reference room:
http://www.pinkfishmedia.net/forum/showthread.php?t=22291
337alant
Negatively Biased
You can also get the 1973 wiring diag from the vinyl engine site
http://www.vinylengine.com/library/linn/lp-12-sondek.shtml
I was going to build one based on that diag so I can try out my old flutter buster.
Martin your suggestion seems much simpler could you post a diag with suggested best componants to use
http://www.vinylengine.com/library/linn/lp-12-sondek.shtml
I was going to build one based on that diag so I can try out my old flutter buster.
Martin your suggestion seems much simpler could you post a diag with suggested best componants to use
flatpopely
Prog Rock/Moderator
neiljadman
Senior Member
Kind of on & off the subject - does anyone have a spare used but serviceable 60hHz motor available?