Finally got around to finishing off this little phonograph. Only took 10 years! Anyway it plays good after I put a new pickup in it, but the speed is fast due to the higher line voltage (122). If I run it on a varic I can drop voltage (110 or so) to get the speed correct.
Has anyone added a small speed control pot to the line voltage side for the motor only? If not, any other way to regulate the motor speed? I did not see any governor adjustment on the motor or idler.
What did you use for the drive? If you used that classic transformer motor, its speed is simply independent of line voltage and only dependent on the frequency. Using proper mechanical advantage (pulley-to-pulley) you create a proper speed.
Otherwise you have to create a drive, no matter how you call it. Whether it is a DC, or variable speed AC.
Morzh
Yes I am using the original transformer drive with the idler wheel. Not an EE but if I understand you, with the original motor, I would need to control the frequency Hz just like a VFD. Well darn don't have any or those lying around.
In my simple mind I was thinking along the lines of a dimmer switch, but figured that would put out way too much RF.
So that must be why the older phonograph motors governor is friction controlled.
I have used a dimmer circuit to slow down a phonograph. When the record speed is dead on accurate, there isn't enough torque to operate the changer or get the turntable started turning. I still haven't figured out what to do with it.
I'm confused with this one. As Morzh said, a standard phono motor (since the late 30's, anyway) is an AC synchronous motor. I've run these anywhere from 60 to 130 volts without affecting the speed (the torque, yes, but not the speed). I've owned phonographs that used the standard 115 volt motor as a voltage drop for the tube in the amplifier (50C5), and the motor ran fine.
There was a discussion on old players running fast a few months ago. It was then pointed out indeed the motors used were voltage dependent to a certain degree. Lowering his A/C voltage on a variac brought the motor to proper speed. If I recall his line voltage was in the mid 120s. I was stunned! It was well explained in the thread, something to do with the motors not being synchronous as I recall but have since forgot.
Jerry
Edit: I found the discussion, look at the last couple posts on the first page.
http://antiqueradios.com/forums/viewtopi...able+speed
An observation I made when restoring the Philco M-15 album length 33 1/3 rpm record player is that it uses the exact same motor and idler wheel as the standard 78 rpm player used in the popular 1201 models. The difference being the 78 rpm uses a 1/4" diameter drive pin off the motor (which drives the idler wheel) and the 33 1/3 rpm uses a (roughly) 1/16" diameter drive pin. Don't know if it applies here but in that case, the diameter of the drive pin or shaft controls the turntable speed.
Jerry
Thanks for the link. I did try a variac again with a strobescope, I was able to dial the RPMs in at 90 to 91. House line voltage today is 121. It is warm here with AC running, line voltage is usually at 123 to 124. So maybe if I want to use this little player more then just to show off, I should get a small variac.
Hope this helped. Variac or bucking transformer. I'm surprised you had to get it down so low. Glad I could help even though I'm not a "collector". Enough about that.
Take care and thanks for your help when I needed a part. This is all about trying to help each other. Just my opinion.
Jerry
Brenda
Small correction: it is the Asynchronous motor (not sure which type but I think it is a squirrel-cage rotor type).
Small correction Morzh? Don't pick on BAD. Heck, I didn't know this stuff, I thought they were all synchronous motors. Glad I could add a little. No idea the difference.
Jerry
The difference is, the async has the frequency of rotor rotation not equal to frequency of stator's field rotaition, and is used for smaller power apps whereas synch motor has the frequencies equal. When you see a passive rotor (a squirrel cage or such) - this is an asynch.
It is the most popular motor today.
PS. I don't pick on anyone, especially Brenda Ann. She's a wonderful girl.
Well, agree with all (I know, Impossible,) but there are 50 cycle AC motors and of course 25 cycle moters, and who knows what else in the whole wide world out there, and some aging idler wheels have been "shaved down" to approximate roundness or recapped inaccurately, and bushings and bearings and lubes and other wonderful stuff on changers and turntables can be daunting. I can recall a turntable that used a clock motor and had to be "trained" to start in the proper direction, I believe it was Thorens, but anyway sold nicely way back when. When asked, I told them that they had two plants, one in Switzerland, the other in Australia and that's how bath tubs drain too. Also remember stuff that could equally be used for turning rather large pottery.
Then there was the Fisher Lincoln, which would play one side of an LP, and then turn it over and play the other side. Well I was a teenager then and mis-spent much of my youth in a distributer-jobber-retailer while going to junior and senior high school and home on breaks from college in my town. Different life after that, was a good 3 decades until I returned to hobby, which I now know is not all that unusual.
Don't know what I had for breakfast yesterday, but do remember some of these tidbits. Anyway, best to all, and "keep the hits on hitting."
Well, anyway, let's all be constructive and supportive of every one of the contributors. I've learned more about "stuff" in the last couple of years since I retired than I knew ever. Best to all and everyone.
A friend of mine had an A-R turntable that could be started with a slight spin in either direction. It was fun to listen to the "backward messaging" in some of those old rock records on it, we didn't have to try to hold the speed manually. Unfortunately, he later replaced it with a Beogram that bounced all over the record if you dared to move in the room while it was playing.
Don't tell my kids, but there was a time when I didn't know if the record was turning correctly or backwrds. Anyway, either a ton of cement or about 8 inches of foam under the base and a plastic top tamed most of feedback from floor and whatever back in the day. Had ears good then and decent vinyl stuff that we liked too.
Some of Bach's stuff sounds pretty good backwards too. Try recording a segment from a synth in MIDI and invert it, even if you are not a maestro. No samples to offer, haven't done it for a long time, but I was surprised.