Small DC Synchronous Motor

Thread Starter

ErnieM

Joined Apr 24, 2011
8,377
I have been trying to obtain a small gear motor like below to fix a nice Christmas snowman I like. So far Amazon has sent me 4 duds built by a company named "Chancs." 5RPM, 12 VDC, 33 mm shaft.

Would anyone know of a good source for such?

Full Amazon listing
 

BobTPH

Joined Jun 5, 2013
8,989
  • Torque:≤0.5kg*cm; Frequency : 50/ 60Hz;
  • 【Application:】 Widely used in Christmas tree, decorative colored lights, hand-made, school project, electric fan shake heads, heaters, prayer cylinders, air conditioners, microwave ovens, glue machines, electric ovens, rotating lamps, electric tables, electric models, electric advertising, electric shelves, dishwashers, control appliances , curtain machines, etc.
  • 【Attention:】 1.The applicable voltage of this motor is DC 12V, USING AC POWER SUPPLY, THE MOTOR DOES NOT WORK!! If you can't judge whether your power supply is AC or DC, and you have any questions about the voltage, please ask the custcome service before buying the motor.
  • 2.When using the motor must be connected to the module, incorrect wiring, the motor does not start, please follow the wiring diagram for accurate wiring, if you do not know how to wire, please contact the customer.
Clearly you need a supply that puts out 12VDC at 50 or 60 Hz.
 

Reloadron

Joined Jan 15, 2015
7,518
I looked at the link and it makes no sense. Unless I have been mislead for about 4 plus decades ... I see where Bob TPH has already covered what I was going to say. Even looking at the Amazon link makes no sense.


  • 【Specification:】 Product Name : Synchronous Motor; Model : TYC-40; Speed: 5RPM; Shaft Diameter: 4.5mm ; Shaft Length: 33mm; Shaft Screw Thread Inner Diameter: M3,(Φ2.8mm); Mounting Hole Diameter: M4 (φ3.4mm); Motor diameter: 40mm;Motor height: 18.7mm;Direction : CW/CCW(UNCONTROLLAB); Torque:≤0.5kg*cm; Frequency : 50/ 60Hz
My guess is you have a 12 VAC motor and not a DC motor. Try applying 12 VAC if you can. I have seen dozens of motors like this and all were AC powered not DC. You will find a 120 VAC 60 Hz example of what you want here. I am sure you can find cheaper. Anyway I would try 12 VAC and my money is on the motor will run.

Ron
 

nsaspook

Joined Aug 27, 2009
13,291
I looked at the link and it makes no sense. Unless I have been mislead for about 4 plus decades ... I see where Bob TPH has already covered what I was going to say. Even looking at the Amazon link makes no sense.


  • 【Specification:】 Product Name : Synchronous Motor; Model : TYC-40; Speed: 5RPM; Shaft Diameter: 4.5mm ; Shaft Length: 33mm; Shaft Screw Thread Inner Diameter: M3,(Φ2.8mm); Mounting Hole Diameter: M4 (φ3.4mm); Motor diameter: 40mm;Motor height: 18.7mm;Direction : CW/CCW(UNCONTROLLAB); Torque:≤0.5kg*cm; Frequency : 50/ 60Hz
My guess is you have a 12 VAC motor and not a DC motor. Try applying 12 VAC if you can. I have seen dozens of motors like this and all were AC powered not DC. You will find a 120 VAC 60 Hz example of what you want here. I am sure you can find cheaper. Anyway I would try 12 VAC and my money is on the motor will run.

Ron
The DC version needs and should have a 'BLDC' driver that usually covered in heat-shrink.
1706918266988.png
 
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MisterBill2

Joined Jan 23, 2018
18,535
I would expect amazon to sell what they call a DC synchronous motor, because they neither know nor care about correct information. That includes the cartoon in post #6 How would anyone explain a brushless DC motor, which uses an electronicly commutated magnetic field, to be connected to it's driver with only two wires???
There nay be, possibly, a small synchronous motor powered by that setup, but that does not qualify it as an actual BLDC device, except to the marketing clowns at amazon.

To check the motors that seem to be duds, use an ohm meter to measure the resistance in both directions. That means check the resistance with the red meter lead first on one motor lead, and then on the other. (Black lead to the opposite motor lead.) An electronic drive package will have resistance values much different between the two.
 

MaxHeadRoom

Joined Jul 18, 2013
28,692
I have been trying to obtain a small gear motor like below to fix a nice Christmas snowman I like. So far Amazon has sent me 4 duds built by a company named "Chancs." 5RPM, 12 VDC, 33 mm shaft.
Would anyone know of a good source for such?
There is quite a few MW turn table motors that are out there LV AC.
$15.00

1706976772118.png
 

nsaspook

Joined Aug 27, 2009
13,291
I would expect amazon to sell what they call a DC synchronous motor, because they neither know nor care about correct information. That includes the cartoon in post #6 How would anyone explain a brushless DC motor, which uses an electronicly commutated magnetic field, to be connected to it's driver with only two wires???
There nay be, possibly, a small synchronous motor powered by that setup, but that does not qualify it as an actual BLDC device, except to the marketing clowns at amazon.

To check the motors that seem to be duds, use an ohm meter to measure the resistance in both directions. That means check the resistance with the red meter lead first on one motor lead, and then on the other. (Black lead to the opposite motor lead.) An electronic drive package will have resistance values much different between the two.
It's not a BLDC motor but you can use two wires from a BLDC driver module as an single-phase AC inverter for a small LV AC synchronous motor.
 
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nsaspook

Joined Aug 27, 2009
13,291
NOT COST EFFECTIVE.
That's not the issue with of these cheap Chinese products. There are huge warehouses full of the motor and modules that were made for pennies.
I can find 1 to 3A ESC modules for under fifty cents from the usual sources.
 
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Thread Starter

ErnieM

Joined Apr 24, 2011
8,377
Here's an interesting development. The first motor I procured was a 12VAC unit which was put aside when my transformer failed. Today a new transformer arrived.

Yep, worked fine driving my AC motor.

Yep, also worked fine driving my all my DC motors.

Several units now going back to Amazon. No wonder they are marked "frequently returned item."
 

MrChips

Joined Oct 2, 2009
30,816
I just finished replacing this synchronous motor in a portable ice maker.
The interesting thing is that in this application, the motor direction is reversible. There is some discussion (which is incorrect) on a physics forum on how they manage to reverse the direction of the motor with just two wires connected to 120VAC.

If you have an idea on how this works I would like to hear it. (I know how it works but I don't want to spoil it for you.)


1708213917089.png
 

BobTPH

Joined Jun 5, 2013
8,989
Are you claiming that you can connect the two wires shown to normal house wiring one way and it runs CW and if you switch the wires it runs CCW?
 

MrChips

Joined Oct 2, 2009
30,816
Are you claiming that you can connect the two wires shown to normal house wiring one way and it runs CW and if you switch the wires it runs CCW?
No. I am saying it is reversable without having to switch wires. (Yes, it is powered directly from 120VAC line power.) In the given appliance (portable table top ice maker machine) there is a tray that holds water to create ice. After about 8 minutes, ice bullets are formed. Then the tray rotates in the opposite direction to dump the ice bullets. I opened the bad motor and there is nothing special in there besides the reduction gears.

1708217023587.png
 

BobTPH

Joined Jun 5, 2013
8,989
Well, when installed there can be a third connection through the case. It could be done that way.

Edited to add: it also might be that it reverses each time power is applied.

I guess I don’t understand what puzzle you are asking us to solve.
 

nsaspook

Joined Aug 27, 2009
13,291
No. I am saying it is reversable without having to switch wires. (Yes, it is powered directly from 120VAC line power.) In the given appliance (portable table top ice maker machine) there is a tray that holds water to create ice. After about 8 minutes, ice bullets are formed. Then the tray rotates in the opposite direction to dump the ice bullets. I opened the bad motor and there is nothing special in there besides the reduction gears.

View attachment 315520
A WAG

If there is no quadrature (polyphase) phase shift (in electromagnetic terms) to start the motor in X direction then some mechanical force rotating the stopped (no net rotation force from a single phase) shaft will cause an induced phase lead or lag in the direction of the mechanical spin that will start it spinning in that direction. The motor can get very hot (and go bad) if it fails to spin for some reason, like being mechanically jammed.
 
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MrChips

Joined Oct 2, 2009
30,816
Well, when installed there can be a third connection through the case. It could be done that way.

Edited to add: it also might be that it reverses each time power is applied.

I guess I don’t understand what puzzle you are asking us to solve.
There is no connection to the case.

The puzzle is: How does this motor reverse direction?
There is nothing visible that would explain how this happens, yet the controller can make it reverse direction.
 

MisterBill2

Joined Jan 23, 2018
18,535
I just finished replacing this synchronous motor in a portable ice maker.
The interesting thing is that in this application, the motor direction is reversible. There is some discussion (which is incorrect) on a physics forum on how they manage to reverse the direction of the motor with just two wires connected to 120VAC.

If you have an idea on how this works I would like to hear it. (I know how it works but I don't want to spoil it for you.)


View attachment 315519
What many fail to understand is that many of those motors will run either direction, randomly. When they run only in one direction it is because an internal ratchet prevents rotation in the other direction. The running mode is synchronous, not induction. They use a permanent magnet. I used to have an analog clock that had a stuck ratchet and so any power glitch and it would reverse.
I just acquired a motor similar to the picture and it will drive upto a stop and then reverse repeatedly. There is no way to predict which way it will run from any start.
 
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