Possible to slow down DC motor to 50 RPM?

I am planning on using a DC motor that spins 21,500 RPM. I was thinking of using a 555 timer to slow it down to 50-100 RPM. Would this be achievable and any foreseeable consequences? I am waiting for parts so haven't been able to try it yet.

Thoughts that come to me:

  1. Bad torque (won't be able to turn my small 0.5M 16T gear)
  2. Won't be smooth rotation due to slowing down so much?

I'm aware I can add gears to slow down, but I'm specifically trying to do it this way to save PCB space.

Are any of these true or anything else that comes to mind?

Motor specifications: 8*10 MM (M30 motor)
Motor height: 20.2 MM (without output shaft)
Output shaft length: 6.5 MM (with worm)
Motor weight: 6 g
Voltage: 3.7 V Speed: 21500 RPM
Current: 0.1 A (blocking 1.44A)
Voltage: 4.2 V Speed: 32000 RPM
Current: 0.1A (blocking 1.61A)

No, that won't be reliable. And yes, when you reduce the voltage (or average voltage with PWM) you are also reducing torque.

You could probably get it to work with "massive" inertia (a flywheel) and some speed-monitoring feedback.

Without feedback you can only approximately control the speed.

Use a gear box to gear down your motor to a bit more than the speed you want; then encoder for speed feedback and PWM control for the speed.

Tiny, high quality and powerful gearmotor selection from Pololu.

jremington:
Tiny, high quality and powerful gearmotor selection from Pololu.

Yep, familiar with those. This is actually the whole reason for the post - I want to reduce the size from that :slight_smile:

Euhm... down to what size, then?

Did you search something like "nano, micro, planetary gearbox" on ebay.
Is this too big?
Leo..

shai:
I am planning on using a DC motor that spins 21,500 RPM. I was thinking of using a 555 timer to slow it down to 50-100 RPM. Would this be achievable

No.

It is designed as a high-speed motor - I doubt if it would run reliably or with any useful torque at 5000 RPM. The only way to get 50 RPM is with a suitable gearbox that steps down from (say) 15,000 RPM.

...R

filter gearhead motor from camera

Would a 10x12x10mm stepper motor work?

I think you can just unscrew the gearbox from those guys.

Note: this part of the above link tracks "Slumpert's" shopping activity on Google.

?gclid=Cj0KCQjwhdTqBRDNARIsABsOl98fZo2yoWozSSlmRi79uKyeEhgAIlpjqqT4To58jfE-HZFb1WDxg74aAiQwEALw_wcB#

gclid is not needed for posting on the Arduino forum.

jremington:
gclid is not needed for posting on the Arduino forum.

Nor is any information after and including the question mark in any eBay, Aliexpress or Amazon product link. :sunglasses:

Dang, guess I just gave away my secret shopping sites..
/smile