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2007 Maxon Motor Group Buy

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#302
I have Maxon 110189 motor (first generation Teres) which should be fine for both 45 and 33 speeds so if you're planning changes to controller could you leave one as is? You can send mine as a last one 😉 It took me a few years to get back to this project .My friend is machining a platter for last 3 years ,seems like he already lost my bearing somewhere ,at least there is a chance for motor and controller ;0)
Regards, L
 
#303
You know, that may be the solution to our problem.

Teres Pulley ratio = 28.26
if using the 110189 (190rpm/V) instead of the 110191 (127rpm/V)
33-1/3rpm = motor 941 rpm= 4.95V
45rpm = motor 1271rpm= 6.69V

So this motor may gives a too low voltage in 33rpm and be ok for 45rpm.

The 110190 (158rpm/V) gives:
33-1/3rpm = motor 941 rpm= 5.95V
45rpm = motor 1271rpm= 8.04V
These values are closer to the values we get with the 110191 using the 23 pulley ratio (13mm pulley)

The motor specs are different in current/torque,etc however. Since this controller is using current feedback that may be problematic.

Mark advice on the matter would be a great help. Anyone can reach him?
 
#304
Mark kindly answer my questions:

Mark answer:
The circuit uses a series / shunt regulator to control the output voltage, it needs to drop at least 2 Vbe across the series CCS. It also needs to drop roughly 2 Vbe across the current mirror for the compensation circuit. Taking 11.4V nominal supply - 4 x Vbe the max output voltage is around 9V.

The no-load voltage for the motor needs to be far enough below that for the motor to be able to develop enough torque to drive the platter. Accordingly, I prefer a no-load voltage of 7.5 volts or less, the 110191 runs at 900rpm (x 20 for 45). The absolute limit is 9V which is 1080RPM hence x 24. The motor will develop very little torque at this speed, so you would need to keep the battery very well charged.

There are several options to get around this:

1. Use a different pulley.

2. use 18V or 24V supply (watch the heatsinks on the transistors if you do this)

3. use an 110189 motor (the original Teres motor) for which 7.5 V = 1350 rpm

4. Use a 226774 motor for which 7.5V = 1538 rpm

5. build a different supply.

I chose option 1, I'm now working on option 5.
 
#309
Up to you to use 2 batteries (24V) supply, but take note that the actual design is not fully compatible:

The complete section of leds indicators would need new part values.
The integrated battery charger won't work.

So it can be done, but I won't do it. This GB is already a lot of work.

I'll try the custom pulley route and stop there for now. Anyway, the pulley was never part of the orginal group buy that was just for the motor if you remember. Pulley was offered as a simple first solution and as a service from me to you guys. Good news is that the actual setup is ok for 33rpm playing.

For more special needs (45rpm). if the Teres custom solution doesn't work out, you may need in the end to get a custom pulley made, but this will have to be an other GB, not this one.
 
#310
pulley

Hi all,

I have been following progress, and had been searching for the file for the pulley made for the last GB. I found it today. It had been moved to a backup drive that I hadn't thought to search. If you are interested in that design, I will be happy to pass it along.

DaveM
 
#313
If my sums are correct it's not a problem for me driving the inner platter of the Systemdek or the Roksan. Although in one of your emails to me Algar, you were suggesting it was tricky to set low voltages on the controller, reading the original thread I get the impression that this is possible with the right combination of DIP switch settings. Even if not I expect the resistor values could be changed. On the Systemdek the subplatter is about 155mm diameter, so the circumference is about 487mm. The 10mm Teres pulley gives a circumference of about 31.5mm, so the gearing ratio is about 15.5. For 33.3rpm I'm looking at about 4.1v and about 5.5v for 45rpm. Motor speeds should be about 520 and 700rpm respectively. The Roksan isn't conveniantly to hand to measure the subplatter diameter, but I expect it's similar. So, I'll stick with a couple of Teres pulleys and the existing controller configuration if that's OK.
 
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