motor and circuit for diy turntable project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
stuartarm: 1/2" thickness increase for a solid platter is a huge amount of mass being added. I didn't see the underside of the platter, but am assuming it is a solid disk of material. If not machined out, then a lot of energy is wasted and contributes little to the flywheel effect vs energy applied.There are a couple of ways to get to the same result. Multiple motors vs. massive platter is one. The key is to conserve momentum.

Feet have been designed in so many iterations that somewhere feet must exist. If wanting to do something strictly custom because you can, that's OK. However unless you have some fairly sophisticated measuring equipment it is unlikely you will improve on existing designs.

I look forward to seeing the end result.

Not solid...hollowed out to about 1/4" from top to accommodate bearing assembly so most of the mass is below top of bearing pivot...
 
Nigel,

Here is the motor I've ordered, 2 of them. Thanks for your suggestions. Looks like I may get away with an old 6.3VAC filament transformer.

24V STEPPER MOTOR
Portescap #S42L048S02-M5. 24V, 5 Ohm, 7.5 Degree per step. 42mm diameter x 22mm. Two mounting holes on 51mm centers. Four 3" leads. Shaft - 3mm diameter x 11mm long. 16 tooth, 9.75mm diameter ...
Read more
CAT# SMT- At AllElectronics. Should be in next week
$2.50 each

Do you have any idea why a 117 VAC synchronous 300rpm motor from an old BIC TT won't start? On turn on it buzzes but no start running. Give it a manual spin and it runs right on speed and very quiet. Ive tried belt tension and slippage adjustments to no avail. If it would start by itself I could it and be very pleased.
Hi, Im planning to build my own motor drive and motor unit, I'm looking into the exact portescap #S42L048S02-M5 model, but is this bipolar or unipolar?
If its bipolar, I can use a dual signal DDS to generate 2 sine wave that is 90 degree out of phase and connected to an audio amplifier and run them at any speed.
My previous experience was using a single wave DDS bought from ebay and a all pass filter to create a second 90 out of phase sine wave to drive my rega TT ( this too can adjust speed) but the all pass filter seem to generate noise on the second sine wave. A dual signal wave generator should generates 2 clean waves and solve this problem.
 
portescap stepper

Hi Frank2908,

To get my TT up and running with the stepper I used an audio editing application to generate a 60Hz sine wave and recorded as left and right stereo channels one being displaced from the other by 90 degrees. Used an old cd player and an old 30WPC receiver to supply the left and right channel output to the portescap coils and adjusted the volume control for minimum motor noise. It took some physical adjusting and tensioning of the motor mounting brackets to eliminate some audible hum of the motor in addition to adjusting the drive voltage. One of my 2 motors very quickly overheated badly. The other one is still running perfectly and stays stone cold after hours of continuous play. I would like to get away from the cd player drive someday but it works so well that I'm severely lacking in motivation. The motor is mounted on a 4x6x2 inch aluminum block and sits outboard of the TT in pod fashion. Power to the platter is transmitted by .006 inch diameter nylon thread from the motor pulley to the TT platter rim. Good luck with your unit. I hope you will be as pleased as I am.
Dealing with the thread drive belt takes some practice, but once you get the hang of it, it just goes on and on with no trouble at all.
Rgds,
BillG

Frank2908;4098441]Hi, Im planning to build my own motor drive and motor unit, I'm looking into the exact portescap #S42L048S02-M5 model, but is this bipolar or unipolar?
If its bipolar, I can use a dual signal DDS to generate 2 sine wave that is 90 degree out of phase and connected to an audio amplifier and run them at any speed.
My previous experience was using a single wave DDS bought from ebay and a all pass filter to create a second 90 out of phase sine wave to drive my rega TT ( this too can adjust speed) but the all pass filter seem to generate noise on the second sine wave. A dual signal wave generator should generates 2 clean waves and solve this problem.[/QUOTE]
 
Last edited:
Thank you, so the portescap is bipolar? How did you remove the gear?
Your method of motor drive is similar to the altman tt right? Im replacing the cd player with ah dual dds model udb 1305 on ebay, i will report results. Im also using medical silk thread for my tt and it run superbly.
 
Thank you, so the portescap is bipolar? How did you remove the gear?
Your method of motor drive is similar to the altman tt right? Im replacing the cd player with ah dual dds model udb 1305 on ebay, i will report results. Im also using medical silk thread for my tt and it run superbly.

Frank,

I didn't want to stress the motor shaft even a tiny bit. So I used a Dremel tool with abrasive disks to grind a flat on the gear, taking it down to a thin skin but not touching the steel shaft. A sharp pointed tool will easily cut through the skin. Then use a couple of good sized screw drivers to gently but firmly lift the gear off. You should pry from opposite sides of the gear simultaneously. If you encounter too much resistance to moving the gear, use the Dremel disk again on the opposite side and the two halves should fall off. I am very interested to see the details of your drive when done.

Rgds,

BillG
 
Frank,

I didn't want to stress the motor shaft even a tiny bit. So I used a Dremel tool with abrasive disks to grind a flat on the gear, taking it down to a thin skin but not touching the steel shaft. A sharp pointed tool will easily cut through the skin. Then use a couple of good sized screw drivers to gently but firmly lift the gear off. You should pry from opposite sides of the gear simultaneously. If you encounter too much resistance to moving the gear, use the Dremel disk again on the opposite side and the two halves should fall off. I am very interested to see the details of your drive when done.

Rgds,

BillG
I got the udb 1305 dual dds from ebay and running my rega real smoothly. The sound is much cleaner than my previous single wave generator + all pass filter ( which was already an improvement from stock)
I also got the portescap but haven't got time to test out
So if you want to remove your cd player from the system, the dual dds works
regards,
 
Frank,

I didn't want to stress the motor shaft even a tiny bit. So I used a Dremel tool with abrasive disks to grind a flat on the gear, taking it down to a thin skin but not touching the steel shaft. A sharp pointed tool will easily cut through the skin. Then use a couple of good sized screw drivers to gently but firmly lift the gear off. You should pry from opposite sides of the gear simultaneously. If you encounter too much resistance to moving the gear, use the Dremel disk again on the opposite side and the two halves should fall off. I am very interested to see the details of your drive when done.

Rgds,

BillG
Hi Bill,
what frequency are you using the Portescap at? I tried to run it at 50hz and 56.4 hz (the frequency of my rega) but there is lots of vibration. Is there any other tweak applied to yours?
Hoang
 
Hi Bill,
what frequency are you using the Portescap at? I tried to run it at 50hz and 56.4 hz (the frequency of my rega) but there is lots of vibration. Is there any other tweak applied to yours?
Hoang

Frank,
I'm running it at 60Hz. You do have to set the amplitude of the drive power. I use the volume control on the audio amplifier and bring it down to the quietest/smoothest motor running. You can also vary the amplitude of the drive to the two windings with the amplifier balance control. YMMV, So with the bass/treble controls you can distort the sine wave. I found that fiddling with shape and balance does make a difference in motor performance but balanced and undistorted works best for me.

Another thought, if you can make a different size pulley to drive the belt, raise the frequency to get smoother running and size the pulley for proper platter speed. You are using belt drive I assume.

Rgds,

Bill
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.