On Mon, 21 Feb 2005, Alan B. Pearce wrote:

>> I want to drive a modest (1A 24V) motor. The circuit must be potted, so
>> heat must be minimal, so I want to use FETs. For simplicity I will use
>> N/P fets.
>>
>> Question: if I want to have the motor turn forward at half speed, should
>> I
>> - turn on left-high and right-low for 50%, and none for the other 50%,
>> or
>> - something like left-high/right-low for 75% and left-low/right-high for
>> 25%?
>>
>> In other words: to control the power in one direction, do you change the
>> on/off ratio, or the forward/backward ratio?
>
> You might want to try searching the 'net for things like "galloping ghost
> radio control" which was a very simple way of getting a two channel control
> from a single servo. it used both frequency of pulse and ratio of pulse
> width to control a motor. The pulse width was used for rudder, and frequency
> allowed some control of elevator. Relied on using a frequency that was low
> enough to let the motor oscillate. It was driven both ways in this case.

Did they call it 'galloping ghost' on account of what it would sound 
like when listened to in a normal receiver ?

Peter
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist