Low Current DC Motor

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DavidGw

New Member
I bought several of these motors from Electronics Goldmine (USA) and was surprised to find they only pull 5 mA (no mechanical load on the motor shaft) at 5 volts.

They are currently on sale for $0.99 each.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G4453
<A href='http://www.goldmine-elec-products.com/prodinfo.asp?number=G4453' Target=_Blank>External Web Link</a>

Dave
 
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Ralpht

New Member
As a thought, small low current high torque brushless, sealed motors can also be obtained &quot;reasonably&quot; cheaply from model train hobby stores. I used Sagami and Mashima ones, the smallest available and whilst they are not $0.99c - approx $10-12AUD, they are very low current even when stalled- 100mA max stalled current, won't burn out easily, and to me worth their weight in Gold. I have seen them as low as $4.00 AUD at times. They will last forever and produce almost no electrical noise and are nearly dead quiet. Many sizes are available at varying prices.
Worth looking out for!

 
 
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DavidGw

New Member
Hi Stan,

Took me a while to find my tachometer. Here are the figures. Note that in order to measure the RPM I had to fit a &quot;propellor&quot; to the shaft - actually a Haagen Dasz ice cream bar stick ... :). This no doubt changes the RPM as it gives the motor a load. It does change the current.

1.5 volts = 750 rpm (5 mA draw with &quot;propellor&quot;)
4.5 volts = 2350 rpm (16 mA draw with &quot;propellor&quot;)

Dave

Edited by - noesisdg on 18/05/2007 14:28:34
 
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manuka

Senior Member
Thanks for data! This alert is very timely as the classic Dick Smith &quot;solar motor&quot; we've used here for some years has become elusive. It also draws 30mA unloaded at ~1V, but is slow spinning. Can you let me know the approx slowest RPM this motor has at ~1V? Applications abound with such a motor. I'd NOT normally consider it feasible, but a direct Picaxe drive may even be possible via perhaps a series resistor. A PV from a hacked solar garden lamp,usually giving 2V at 30mA in bright sun, may be all one needs for driving a motor &amp; an LED etc.

EXTRA: I've just been in touch with the US firm mentioned &amp; am considering a bulk order (100 up?). Anyone &quot;down under&quot; want to join in ? Of course I'd really like a sample first, but the firm has declined. Stan



Edited by - manuka on 19/05/2007 00:50:16
 
D

DavidGw

New Member
Stan,

I did a quick experimental hookup with a 220 ohm resistor in series with the motor on 5 volts. It runs fine, pulling 5 mA with no load on the motor shaft. Voltage across the motor is 4 volts, so figure it is doing at least 2000 rpm. So that would be perfectly safe for a direct interface to any PICAXE.

Dave
 
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