Author Topic: need to have a silent motor controlled by an ipad  (Read 750 times)

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Offline freeeeemanTopic starter

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need to have a silent motor controlled by an ipad
« on: December 17, 2013, 03:51:39 PM »
hi all,

i need to make a mechanism that hits a gong and is controlled by an iOS device. since the goal of the operation is to here the gong noise, i'd like to make the servo be as quiet as possible.π

it seems like the easiest thing to do is to put a servo in a sound proof box. it's super quiet if i just have the servo sitting in there, but once i screw it down, i can't seem to keep it quiet. ideas?

Offline jwatte

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Re: need to have a silent motor controlled by an ipad
« Reply #1 on: December 17, 2013, 06:32:08 PM »
You need rubber grommets to screw the servo into. Otherwise, the servo vibrations will be amplified by the box that they're rigidly attached to.

Other possible quiet options:
- use a stepper motor -- no gearbox, can be very quiet! (especially if not microstepping or using PWM.)
- use a gravity pulley to run the gong strike. Use a small motor at some later time to wind the pulley again, when the noise doesn't matter.
- Use a spring to drive the gong strike, and use a motor to wind the spring, where you can more easily put the whole motor+spring assembly into a single box.
- Use a solenoid or other linear motor to drive the gong strike. If you start them softly, they make very little noise.

Offline hobbes

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Re: need to have a silent motor controlled by an ipad
« Reply #2 on: December 17, 2013, 08:41:02 PM »
Electroactive polymers ( artificial muscle ) would be the quietest way to do it. If you can get your hands on it.


Offline freeeeemanTopic starter

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Re: need to have a silent motor controlled by an ipad
« Reply #3 on: December 17, 2013, 11:40:59 PM »
what great suggestions! i love them all. i'll get testing. thanks!

Offline Roman505

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Re: need to have a silent motor controlled by an ipad
« Reply #4 on: December 18, 2013, 04:21:58 AM »
Continuing in the vein of the answers already provided, isolating a servo could be as simple as using hot glue or double-sided tape on a firm rubber sheet. Basically, you want to remove all potential mechanical connection to the enclosure. On alternative actuators, here is one which is also new to me, and fairly interesting:
MigaOneDemo.mp4
and
MigaOne SMA Actuator Moving a Binary Latch - Miga Motor Company

Offline freeeeemanTopic starter

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Re: need to have a silent motor controlled by an ipad
« Reply #5 on: January 07, 2014, 06:06:01 PM »
update:
i got the servo to be relatively quiet by packing a box w/ foam, but the servo wasn't strong enough to get the job done. i ordered a stronger servo hoping that does the trick. i'm leaning towards servos b/c they seem to have more options for connecting to iOS devices.

Offline CJAlbertson

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Re: need to have a silent motor controlled by an ipad
« Reply #6 on: January 13, 2014, 11:38:08 AM »
hi all,

i need to make a mechanism that hits a gong and is controlled by an iOS device. since the goal of the operation is to here the gong noise, i'd like to make the servo be as quiet as possible.π

it seems like the easiest thing to do is to put a servo in a sound proof box. it's super quiet if i just have the servo sitting in there, but once i screw it down, i can't seem to keep it quiet. ideas?

If sticking a gong a motor is NOT the correct method.  What you what is a electromagnet solenoid.  Build a mallet on a hinge then you energize the electromagnet and the mallet is pulled into the gong.   These are no moving parts to make noise other then the mallet.

I think the servo would be to slow and not have enough force.   

You can vary the sound level be how much current is in the magnet

They make doorbells that work lie this.  Many times the "mallet" is a slug of steel that is inside the coil of wire and get shot at the tubular gong like a bullet.  There is usually a weak spring that keeps the hammer back some distance but gravity could work as well if the gong were above the hammer..

Two magnets could work too.  One to pull it forward and one to pull it back.   Bt a spring is cheaper than the second magnet.
Chris A. in So. Cal.

 


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