Seeking small motor with 1 revol. per minute

[petersob]

I am designing a portable rotation system to measure microphone directionality, which is to rotate full 360 deg each time I trigger Start. My 360 deg measurement lasts exact 1 minute, so I need a very small power, 1 revolution per minute motor with gearbox, reducing motor speed. I have a gearhead motors from Goldmine, but they rotate still too fast, about 1 rev. per 5 sec - and consume too much power, about 90 mA at 1.5V and 200 mA at 9V, with about 5 Ohm resistance. Better would be 50 mA or less, at 3V - since no power is really needed with very small load. Has anyone designed such rotating device and could share this experience - or knows about something close, so I can modify existing unit? Unfortunately, I can not use stepper motors, because of ultra low noise requirement, below 20 dB SPL. They do generate sound as I noticed, too high level. Motor should be able to move in both directions, as voltage polarity changes, which narrows gearbox choices. Peter

 

[electricpete]

Can you adapt the minute hand on a clock?

 

[electricpete]

Whoops... I meant second hand.
(the one that goes around once per minute).

 

[petersob]

Unfortunately, no clock mechanizms, even electrical ones, that are larger and stronger. Small power is required, but not that small... Microphone cable still will be rotated and moving shaft holds microphone weight. Sometimes hand held microphone weights 1/4 LBs, sometimes microphone catrridge weights 0.01 LBs.
The only idea I have so far is to make additional gearbox with speed reduction 15:, added to motors I have. Peter

 

[cbarn24050]

Hi, if you drive a stepper motor with sine waves with a 90 deg phase shift then you can get get quiet operation.