[DeTomaso] NPC: Electric validation

Dave Londry davel at emspace.com
Fri Jan 21 17:09:40 EST 2011


That only works at the high voltage end of the range Paul.
A 12V DC motor will run faster as you wind the voltage up,
  probably to 16 V or more until something decides it doesn't like the 
volts and quits.
When you try to slow it down, you run into a problem,
it maybe works down to 9 or10 V and then says tohellwithit and stalls.

To do manageable speed-control you need pulsewidth modulated control (PWM)
that fires full voltage pulses at varying duty cycles.
That works down to maybe 20% of normal speed and then friction just 
stalls it,
  but it's really good above that.

12V  ____  ____  ____
     _|   |_|   |_|   |_ Fast
0V
12V  __     __     __
     _| |____| |____| |_ Slow
0V

There is variation between brushless and non-brushless motors,
  plus the bigger they are, the finer you can control them.
dave


On 1/21/2011 1:33 PM, Paul - Home wrote:
> I have buddy looking to use a car window motor to control a valve and
> its been too long since I last worked with any motors so I need a memory
> boost.
>
> The voltage applied to the motor (like the one that drives our windows)
> will control the speed of the motor, more voltage = more speed, with
> some limits, right?
>
> Paul
> #9270
>
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