/diy/ - Do It Yourself

>>797344
I also have another power supply from another manufacturer with the same rating. It pulses at a slightly faster rate, but still the same behavior.

>>797344
Can you measure voltage and current while running it?

>>797352
I'm going by my university today to borrow a DMM, I don't have one handy. I really ought to for this project.

What should I measure, once I get it?

>>797344
Is the motor getting really hot? They have an internal overload protection that trips out when too much current causes it to overheat.

You need a controller. Permanent magnet motors are a lot like brushless motors in the sense that a plain old dc current running through it wont actually get the motor to spin.

http://cache.freescale.com/files/industrial/doc/brochure/BBPRMMAGSYNART.pdf


If your power supply is a controller, then idk, theres probably something wrong with your motor.

It's probably because dc motors draw above their rated amperage during startup. Looks like the power supply is shutting down and taking a second to reset and try again. You could get it to work by starting at a lower voltage and switching to 12v after it's up to speed.

Or your power supply is lying about its 5amp output. Pretty commonplace for cheap power supplies

>>797361
It's totally cold

I don't understand exactly what goes on with current and power supplies -- does the motor "pull" 3.8 amps, or does the power supply "push" 5 amps? If it's the latter, then you're right, and I'll need to find a way to lower the current

>>797366
Mind me asking what you're planning on doing with the motor?

>>797364
wait what that can't be right
the power supply isn't a controller, just your standard brick-on-a-cable with a barrel jack

I've also tried running it though the controller we'll be using:
http://cytron.com.my/p-md10c
but same behavior

>>797365
that certainly sounds plausible about it drawing more amperage, anything i could embed in the circuit to mitigate it? Maybe stick a capacitor somewhere or something?

>>797369
I've posted it here before, senior design project: Need a reversible, varying speed motor with 7 inch-pounds of torque operating at 250 RPM to raise and lower a 20-pound door with an 18-pound counterweight in a pulley system

>>797344
Looks to me like it needs a start capacitor, or a run capacitor, or both on it. But my experience is on the higher voltage motors.

>>797372
>>797364
Yeah, I'm right, the form-factor is listed in the manual here >>797344 as 1.0 -- it just needs a straight DC source

>>797374
What size capacitor, and where do I stick it?

>>797379
>>797374
oh come on don't abandon me

>>797379
dc permanent magnet motors do not use capacitors.

you need to use a 12v battery ( a car battery or small sealed lead acid - the kind you find in a UPS or battery backup ) for correct operation. the +12v rails on a PC ATX power supply should work too.

you may be able to use that power supply to see if the motor works by removing the gearbox.

>>797365
my thoughts aswell

when you power it on, stick a multimeter on the power in wires, if it shows an alternating high/low voltage chances are that your 12 volt 5 amp power-supply just ain't cutting it

op have you got access to an old pc power-pack?
if you have (and it's rated for more than 6 amps) i would try that, it'll be the black for negative and the yellow for positive 12 volts

you can make a new computer psu work as a 12 volt power-pack as-well by joining the green wire to any of the black wires as shown in this video https://www.youtube.com/watch?v=5FWXgQSokF4

if it still pulses you my need to send the motor back to the manufacturers for a replacement

Like previous posters said, try to find out if the inrush current of the motor is causing the power supply to go into short circuit protection by measuring the voltage at its terminals. When a power supply sudddenly needs to deliver a lot of juice it can go into panic and turn of the output. If that is the case you can use the PWM capability of your controller to slowly increase the power going to the motor. Simply go from 0% to 100% duty cycle at a frequency of 20 kHz over the span of two or three seconds. The output capacitor of the switch mode power supply should smooth out the voltage and you get a nice clean and smooth start up as a bonus.

Another possible cause could be an inproper installed gearbox. Try running the motor without it.

>>797425
That is excellent, thank you
>>797414
>>797419
thank you guys as well

>>797344
Are you using a switching power supply? That's probably the problem. Not all switching power supplies are intended for use with large inductive loads like motors. Also there's startup current. I think you'll find that the supply is cutting out on you. Try a 12V battery or a 12V linear supply (doesn't need to be regulated or filtered, even, for a motor, a car battery charger will work).

>>797450
The problem is that battery power isn't an option here -- this thing is going to be a semi-permanent test fixture in a composite company's laboratory; part of my design task is to make the whole thing as low-maintenance as possible. I'm going to go with what >>797425 said and ramp up the voltage, since that's been the plan all along -- I was just connecting it directly to the power source to see if the thing even worked.

>>797344

I think you need a NEMA Type K DC power supply.

>>797467
oho, what makes you say that?

>>797476

I think you need a free wheeling diode. It helps in providing smooth current to the load and eliminates the negative voltage across the load. It gives continues current to the inductive load.

>>797477

Should have added this is what a NEMA Type K is, a power supply with a free wheeling/ flyback diode.

>>797477
>>797479
Sweet lord those are pricey. Is there anything I can do to roughly emulate their function? Can't I place a diode between the two leads of the motor?

>>797344

What is the model of that motor?

Do you have a full picture of the nameplate?

>>797481
for an inductive load you need a freewheel diode to absorb the collapsing field and protect sensitive semiconductors.

if you want to you can add a diode in parallel with the motor, just make sure you put it in the right way around otherwise you will essentially short out the power supply.

i dont think it will make much difference honestly.

http://www.electronicsteacher.com/robotics/robotics-tutorial/advanced-robotics/controlling-dc-motors.php

>>797366
>motor "pull" 3.8 amps
it's bad terminology ; but in that situation yes.

The power supply is a constant voltage source [most things are] and it will suply up to 5amps - maybe.
If nothing is connected then the power-supply will just be at 12volts , no-current.
If you connect a tiny little car-interior-light bulb then the current will be 0.416666amps [assuming a 5watt bulb]

>>797493
Dayton 7C390, which is an assembly of Dayton 23L376 motor with Dayton 23L522 gearbox

>>797498
>>797450
>>797425
>>797419
WHEW LADS
alright, check this video of it running:
https://www.youtube.com/watch?v=4vPzc60lihE

I set it up with a little dial potentiometer as a speed controller (0-1023 reading, divided by 4.1, gives 0-255 as the pwm output from the Arduino to the controller)

however, turn up the volume and listen to the sound it makes. it's pretty unpleasant, but it MIGHT just be the normal sound of it running. I don't know. You guys have any input?

It doesn't get hot, but I've only let it run for like ten seconds straight (and in practice it'll only be running for like six seconds at a time).

>>797419
>>797365
oh, and you guys were totally right -- when i looked down at the power supply, its little indicator LED would blink off every time the motor shut down when it was pulsing

sticking an inductor in series with the motor may fix this. an inductor opposes changes in current, so the inrush current will be tamed. a capacitor wont help in this task, nor will a freewheeling diode. as for the size of the inductor, that's determined by trial-and-error. you want the smallest number of turns that works reliably.

sticking an inductor in series with the motor may fix this. an inductor opposes changes in current, so the inrush current will be tamed. a capacitor wont help in this task, nor will a freewheeling diode. as for the size of the inductor, that's determined by trial-and-error. you want the smallest number of turns that works reliably.

the inductor thing worked for a previous poster who had a similar problem a few months back.

>>798080
it's alright, I was never going to ask it to go straight from 0 to full power instantly; I'd always planned on a relatively smooth acceleration and deceleration since it'll be moving a fair amount of inertia. I was only trying to test if the thing even worked, and the pulsing just freaked me out.

The main problem now is the whine, but a bit of googling has told me that that's typical for PWM with a DC motor. Switching to a different pin has fixed it, to an extent

Assembly of >>797372 is going very well; here's a test video
https://www.youtube.com/watch?v=oBEIYKnF2u4

that horrible scraping sound is the pulleys, which can move freely side-to-side on their spindles and scrape against the sides. We'll be replacing those.

>>797372
What software did you design that with?

And here I've attached the counterweight and mounted the motor:
http://youtu.be/q0qe9s-KwF0

>>799773
SolidWorks, yo

>>800313
bad link
http://youtu.be/2y9wCnAcMGc