Quiet Motors for Lab Experiments - Page 1
Forum section: electronics / projects

author: eerocketman
author_rank: Contributor
timestamp: November 19, 2017, 09:03:36 pm
content: Hi Everyone,I am currently studying the behavior of mice in a lab. I would like to create a fixture that includes a motor, but I ma worried that the sound from the motor will interfere with the conditioning of the mice. Does anyone have suggestions for small brushed DC motors that are very very quiet. OR would getting a regular motor and creating a sound proof housing be a better solution to this problem?Thanks!

author: cdev
author_rank: Super Contributor
timestamp: November 19, 2017, 09:15:17 pm
content: The quietest computer fans might be good places to start. You could seriously undervolt them if you needed even less noise from them. then use nylon gears - plastic gears to transform the force to whatever you needed quietly.

author: _Wim_
author_rank: Super Contributor
timestamp: November 19, 2017, 09:24:52 pm
content: Quote from: eerocketman on November 19, 2017, 09:03:36 pmWhat torque and rpm you need. For high quality motors and professional projects Maxon Motors is one of the best and plenty of choice. There DC motor running at low RPM (motors without a gear box that is) are very quiet.As suggested above, if high torque is needed and thus a gearbox, go for nylon gears instead of metal gearing, but I think a better approach is to oversize the motor and run at low rpm

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 19, 2017, 09:30:59 pm
content: To do what? Wax motors for simple actions are good.

author: ChrisLX200
author_rank: Unknown
timestamp: November 19, 2017, 10:03:59 pm
content: Mice soon get used to continuous low-level background noise, so run the motor (or play a looped soundtrack of it) continuously then they will ignore it.

author: beanflying
author_rank: Super Contributor
timestamp: November 19, 2017, 10:44:24 pm
content: These are great but $$$$https://www.maxonmotor.com/maxon/view/content/products

author: Terry01
author_rank: Frequent Contributor
timestamp: November 19, 2017, 10:53:34 pm
content: Brushless motors are more economical and quieter too. Both by quite a bit. The Internet is awash! You should get something for very little £££s. Remember everything you need will be tiny size!Good luck!

author: nidlaX
author_rank: Frequent Contributor
timestamp: November 20, 2017, 01:59:42 am
content: Quote from: ChrisLX200 on November 19, 2017, 10:03:59 pmDefinitely consider doing this. Mice apparently can hear between 1kHz to 70kHz (https://en.wikipedia.org/wiki/Hearing_range#Mice), so you may want to profile the environmental noise of the entire setup before you begin your experiment. You might also consider some degree of sound isolation between the motor and the mice's enclosure using some transfer gearing or pulleys.

author: jmelson
author_rank: Super Contributor
timestamp: November 20, 2017, 02:19:12 am
content: Quote from: beanflying on November 19, 2017, 10:44:24 pmI second this, Maxon motors can be extremely quiet if run at relatively low speeds.Jon

author: eKretz
author_rank: Frequent Contributor
timestamp: November 20, 2017, 12:25:09 pm
content: Some other very high quality motor brands (very quiet running) in addition to Maxon are Faulhaber, Bühler, and Portescap. Be forewarned, none of them are budget priced. Abundantly available secondhand on eBay and some surplus sites for good prices though.

author: CM800
author_rank: Frequent Contributor
timestamp: November 20, 2017, 02:06:41 pm
content: Quote from: nidlaX on November 20, 2017, 01:59:42 amThat could be a concern indeed considering most drives operate at 20kHz PWM.They could well hear all the tuning loops etc.If you wanted absolute certainty of silence (beyond testing the whole noise range)I'd look at using some kind of "hydraulic motor" or pnumatic motor which will have no PWM sounds, you can then drive that from a distance with a small power-pack.If you can't find a Hydraulic motor, I'd look at 3d printing something. There's probibly something suitable somewhere.Honestly Overkill (small plastic 3D Printed part would do you better if it's low power)http://www.surpluscenter.com/Hydraulics/Hydraulic-Motors/Low-Speed-High-Torque-Hydraulic-Motors/?page_no=1&sort_by_options=price+ascBit of a novel solution.

author: ChrisLX200
author_rank: Unknown
timestamp: November 20, 2017, 05:27:32 pm
content: I was in the animal behavoural science area for more years than I care to remember, and I can tell you that you will need to acclimatize them to the test environment over a period of days. If you don't then subtle traits will be swamped by exploratory behaviour. Even someone new walking into the room (who smells different) will trigger intense interest from the animals. We used to use sound-proofed rooms together with a backround sound level sufficient to mask normal lab activities within. The room also had offset day/night lighting cycle because the critters tend to sleep most of the day and are active at night. There are far too many other considerations to provide advice here, just know that if you expect to get valid data that a peer review won't destroy you need to take the test environment very seriously.edit: The actual noise level - provided it is not excessive - is irrelevant. Mice/rats will consider any new noise they are not acclimated to as a threat until proven otherwise. It's that which you need to control and which takes the time.

author: eerocketman
author_rank: Contributor
timestamp: November 20, 2017, 06:45:59 pm
content: The issue is that this is an auditory experiment where the motor is only active when there is a specific sound that we want the mice to react to. The test environment itself is completely sound proof with its own day night cycle.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 20, 2017, 09:26:58 pm
content: Quote from: eerocketman on November 20, 2017, 06:45:59 pmI'd say you risk influencing your experiment even with the quietest motor. You never get them entirely without sound and vibrations. It's probably a good idea to design the experiment in such a way that the motor sound can be excluded from the results.

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2017, 02:38:12 pm
content: Quote from: nidlaX on November 20, 2017, 01:59:42 amThis suggests up to 110kHz.https://en.wikipedia.org/wiki/House_mouse#Life_cycle_and_reproductionAvoid PWM.Mouse's hearing is less sensitive than humans' at lower frequencies, <1kHz, so even if you can hear it, that may not be a problem. Perhaps it might be better to use mains frequency motors? The lower voltage type, designed to be run off a transformer. If a variable speed is required, it could be driven with an audio amplifier (class AB, not class D!) and a suitable sine wave signal, though plenty of filtering would be needed if it's digitally generated.Have you considered smell? Mouse have a very sensitive smell, much better than humans. The lubricant used in the gear system and many plastics emit odours, which could be off-putting to mice.

author: BrianHG
author_rank: Super Contributor
timestamp: November 21, 2017, 02:59:59 pm
content: Look for DC motors designed for 0 cogging, fat wide diameter bodies, balanced, and run the at low RPM. You may add a heavy flywheel to further lower noise.Your drive power supply should be linear if you are worried about high frequency noise coming from a PWM drive.For low rpm and low strength, you may also look at 3 phase or multi-phase brush-less motors fed with low power fundamental square wave or sine wave. Something similar to what you would find in old 3.5inch floppy drive motors. Slow regulated speed and silent, well the better ones were silent...

author: xani
author_rank: Frequent Contributor
timestamp: November 21, 2017, 04:04:41 pm
content: Quote from: nidlaX on November 20, 2017, 01:59:42 amHuh, didn't know it goes that high, I wonder if they can hear some DC converters then

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2017, 04:49:03 pm
content: Quote from: BrianHG on November 21, 2017, 02:59:59 pmGood idea, but beware of square waves, which can cause buzzing, at the harmonic frequencies, even if the fundamental is inaudible to the mouse.

author: m98
author_rank: Frequent Contributor
timestamp: November 21, 2017, 09:59:59 pm
content: What are you trying to accomplish with that motor?

author: beanflying
author_rank: Super Contributor
timestamp: November 22, 2017, 01:36:26 am
content: The maxxon motors don't cog (rotor design), have no brushes and linear speed control is the way to go to avoid the frequency issue. Not to mention generally around 80-90%+ efficient so little heat generated.Brushless BDLC speed controllers are very noisy in particular and chopper dc circuits the same.