• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

12V motor running at 60 RPM

Status
Not open for further replies.

oliveros

New Member
Hi group,

I am interested in control the speed a 12V, 5300RPM motor similar to the one below.



I need get 60RPM, I have tested some motors with reduction gears, but are very noisy.

it is possible reduce the speed only by electronics? without gears ans pulleys?

if not, wich motor could I use, the required perfomance is max 60 RPM to impulse a head of a mini peristaltic pumps, the low noise is very important!.

Please do not hesitate to ask me any question that you may have.!
 

Sceadwian

Banned
No it is not possible, not while retaining the desired torque at least. Any motor you find that spins that slow is going to have a gearhead on it.
 

oliveros

New Member
hi Sceadwian, thaks for your anwser.

there is another kind of motor that could do that, like steppers?. I have opened the case of some scientific equipments, and there are motors inside, without reductions gears that are running at low speeds without loosing torque.

any help is welcomed!
 

Sceadwian

Banned
Steppers are nothing like the motor you posted, so I didn't mention them, because you requested something like the motor you referenced.
Depends on how much torque you need, and if you can accept that it's going to be slightly 'jerky' when it moves.
What you really need to fully define is what you're trying to do, not what you think you need to do what you're trying to do.
 

oliveros

New Member
I am not sure the kinf of motor that I could I use, the picture was only an example.

the required perfomance is max 60 RPM to impulse a head of a mini peristaltic pumps, with a hose of 6 mm external diameter.
 

user_88

Member
The motor rpm specification that you quote might be the 'no load' rpm.
With an actual load torque, such as a peristaltic head, the working rpm could easily be half that value.
Look around for a worm gear arrangement, such as shown here:
HowStuffWorks "How Gear Ratios Work"
If you can find gears made of nylon or other non-metallic material, they will run more smoothly and with much less noise.
 

Sceadwian

Banned
Those are very commonly driven by gearhead AC motors. Yeah, they're kind of noisy. Why do you need to be quiet?
 

oliveros

New Member
is for a laboratory equipment, to culture cell and bacterias, and there is proven that the noisy and vibrations damage the cell cultures,

that is the reason what the noisy gear reductions boxes are not allowed
 

Sceadwian

Banned
So don't allow direct physical coupling...
 

user_88

Member
QTC410 - Component Data Base

either PG1-40R1 for 40:1 reduction, or PG1-50R1, for 50:1 reduction.

A separate concern would be to ask how much mechanical power is required to operate the pump head, at a suitable speed....

The power requirement of the pump should be less than that provided by the motor.
 
Last edited:

Bob Scott

New Member
If you use a stepper motor with the standard step angle of 1.8 degrees per step, and if your electric power AC frequency is 50 Hz, you can drive the stepper motor with two phases of AC power and obtain a very smooth rotation locked exactly at 60 RPM.

Use 2 phases of 3 phase AC or a large AC capacitor to delay one winding's current with respect to the other winding. You'll need one or two power transformers.

Exactly how much torque is required?
Stepper motors have more torque than regular DC motors. If you use a regular DC motor you may need a gearbox just to multiply the torque.
 
Last edited:

dougy83

Well-Known Member
suhasm said:
Cant you use PWM?
It should work pretty well..
PWM? A cheap DC motor has 3 poles (which are somewhat stable positions), and will try to jump between each (very jerky) if the applied voltage (and consequently speed) is low. If the voltage is too low, the motor will not turn.

Using a DC motor with gearbox is good. Using a stepper motor with sinusoidal drive is also good.

The sinusoidal drive may be provided using bob scott's idea, or you can use an sinewave (or close to sinewave) oscillator driving an RC phase shifter and some amps, or just use a ready made micro-stepping stepper controller with clock source.
 
Last edited:

Willbe

New Member
Maybe use a huge flywheel with your orig. motor? In that case your motor would put out pulses of torque that would be filtered by the wheel.
If speed is voltage then your motor acts like an open-circuited "current source" and the flywheel would convert the "infinite" speed into a reasonable value.
Use PWM to get the req'd power out but don't put pulses of current into the motor of more than 5x rated current or you might demagnetize the motor.
 
Last edited:
Status
Not open for further replies.

EE World Online Articles

Loading
Top