The Official Turntable Drive System/Motor Thread!

[a.wayne]

Hello Stew ,

Thanks for the response .. I'm looking for an replacement to my noisy AR motor and you did mention yours was noisy until lubricating , I want one quiet out of the box , noisy out of the box might be a problem, long term ...




regards

[gtyler]

I have a question.

I have this motor:
HURST 300 RPM SYNCHRONOUS MOTOR/STEPPER MOTOR - eBay (item 380176978259 end time Dec-06-10 16:48:45 PST)

And two of these transformers:
Antek - AN-0209

My plan, as i mentioned before, is to use an amplifier to boost the signal form an mp3 file that I have created to drive the motor. Then to use the transformers to boost the voltage to the required level for the motor. I have finally got all the components, and I would really like to try this motor out, however, when I first got everything together I gave it a try and it fried the amp that I was using. The amp was on it's way out anyway. It was having some severe problems, but it was working to drive a smaller stepper motor that I had. When I hooked it up to the transformers, and to the motor, it worked for about 5 seconds then it quit forever. It may have been my bad connections shorting or coming loose that caused it to blow, but I'm worried it was the load.

So what do you think? I have been told before that an amp should have no problem driving this setup, but I'm skeptical. If I get another amp am I just going to blow it too as soon as I hook it up? Do I need a more powerful amp or a different type of amp to drive this setup? Is there a way that I can measure the impedance of the motor and transformer assembly? Please let me know if you have any comments.

Thanks for all your help!!

[rcthweatt]

gtyler -Had to add 4 one 0hm 10W resistors(Ratshack) with my Dayton T-amp, which solved the problem. My transformers are 24:120/240/480V control transformers, driving the 24V winding(very low DC resistance), 480V is out to motor.

[Greg M]

I have a motor that I need some help with. I've had it for sometime and have always wanted to do something with it because it such a lunker.
I need some help hooking it up. Here's what the ID plate says....

Elinco Hysteresis Synchronous Motor
115vac.....1 phase........60cycle...... 1/40 hp
1800 rpm.....0.6 amps......Temp Rise 40° C
Cap Value 3 uF.......Cap Volts 220......Duty Cont
Insulation Class A

It has 4 wires
white w blue stripe
white w yellow stripe
white w red stripe
white w green stripe

I'd like to hook it up just to see if it's even in the ball park.


Anyone help with the wiring?

[jackinnj]

Originally Posted by Nanook

Using an AC motor, one needs to find something that can create a rock solid frequency.

Recent article in AudioXpress describes a method of dividing down a crystal, then using a switched cap low pass filter to derive a very stable sine wave -- the same general idea was described by Gary Galo in 1986 (Audio Amateur, predecessor to AX -- and cited a previously written article in Electronics World, I believe that was the publication). Linn LINGO seems to use 2 XO's for 33.3 and 45RPM.

The problem gets trickier if you want to listen to discs that were recorded when speeds were somewhat less standardized -- but you could do this with a DSP chip from ADI or TXN.

[benb]

For direct digital synthesis there are chips such as this:
AD9833 | +2.3 V to +5.5 V, Low Power (20 mW), Programmable Waveform Generator in 10-Pin µSOIC Package | Direct Digital Synthesis ( DDS) & Modulators | RF / IF ICs | Analog Devices
At the stated max output frequency of 25MHz it has a frequency resolution of 0.00625Hz, which should be enough for most people - the frequency steps around 60Hz would be:
59.99375
60.00000
60.00625
...
and if that's not good enough resolution, just lower the input clock frequency and the steps drop in size proportionally. It needs a serial interface to set up the registers for the proper output frequency, easily done with a microcontroller, which can also be used to drive a display showing output frequency, or even scale it to show turntable speed in RPM.

Even a small microcontroller by itself can give a good crystal-based 60Hz sine wave with increments of 0.001Hz or smaller with the proper programming to implement a numerically controlled oscillator in software. A DSP for 60Hz is overkill.

Here's the Wikipedia articles, though they have much technical info but little in basic explanation - surely there are other web articles on the subject that explain the basics better - the idea isn't that complicated:
Direct digital synthesizer - Wikipedia, the free encyclopedia
Numerically-controlled oscillator - Wikipedia, the free encyclopedia
All the stuff about suprious signals and noise is for generating RF sines in the MHz or tens of MHZ range. At 60Hz some simple filtering will make a sine wave with less noise and distortion than one ever sees from the power line.

[Mark Kelly]

Originally Posted by Greg M

I have a motor that I need some help with.

Elinco Hysteresis Synchronous Motor
115vac.....1 phase........60cycle...... 1/40 hp
1800 rpm.....0.6 amps......Temp Rise 40° C
Cap Value 3 uF.......Cap Volts 220......Duty Cont
Insulation Class A

It has 4 wires
white w blue stripe
white w yellow stripe
white w red stripe
white w green stripe

I'd like to hook it up just to see if it's even in the ball park.


Anyone help with the wiring?

Yes.

Despite what the label says it's actually a three phase motor. The combination of the phasing cap and the winding inductance can be used to create two faked phases to run it on a single phase supply. An article which explains how this works without me having to type it is Here.

Motor performance is however vastly improved if it is run on a dedicated three phase supply.

I'm guessing that the four wires mean that the actual motor is star wired: looking at Fig. 1 there are four junctions that lead to the coils - one at the outer end of each coil and one in the centre of all three. You can confirm this by measuring the wire to wire resistance - there are 6 possible pairs of wires and three pair will show half the resistance of the other three pairs. One wire will be common to each of the first three pairs and it is the centre of the star.

,,

[Greg M]

Thank you
I've been trying to figure this motor out for years

[Nanook]

I just got a copy of November's issue of audioXpress, where an AC turntable power supply has been presented using a 20.0 MHz microprocessor. This has a lot of appeal to me, a complete standalone solution. I'm certainly not an electronics designer (unlike Mark Kelly), nor have I ever pretended to be. I mainly work on the relatively (tweaky) simple mechanical side of things. I've developed patience when hunting down and isolating mechanical noises and aberrations, but haven't really delved into much digital, or electronics stuff. In the past I have, but I now have little patience for that side of things. I may have to re-develop that skill set.

jackinnj, as you suggest, using a faster running processor could provide more accurate adjustments, but only if I can validate the speed of rotation. A frequency generator and counter would make a lot of sense, but are not in my budget currently. I use a digital tach (+/- 0.05 RPM) to verify speed performance. My old Oracle has a stable speed (measured) of 33.4 RPM. This equates into a 0.2% speed error or .1 RPM, +/- 0.05 RPM. Better than I can hear.

The other solution that I have presented numerous times is the use of an mp3 player as suggested by Charles Altmann.

Both the frequency generator and an mp3 player require an amplifier , a trim pot somewhere, and a transformer of some sort. I do like the idea of microprocessor control though.

thanks again for the references

[Greg M]

Originally Posted by Mark Kelly

Yes.

Despite what the label says it's actually a three phase motor. The combination of the phasing cap and the winding inductance can be used to create two faked phases to run it on a single phase supply. An article which explains how this works without me having to type it is Here.

Motor performance is however vastly improved if it is run on a dedicated three phase supply.

I'm guessing that the four wires mean that the actual motor is star wired: looking at Fig. 1 there are four junctions that lead to the coils - one at the outer end of each coil and one in the centre of all three. You can confirm this by measuring the wire to wire resistance - there are 6 possible pairs of wires and three pair will show half the resistance of the other three pairs. One wire will be common to each of the first three pairs and it is the centre of the star.

,,

Checking this motor, my Fluke meter tells me that there are only two combinations that yield any resistance.

Blue-----Yellow 200 ohms
Green-----Red 58 ohms

not what I was expecting?