[PD] Re: [PD-announce] PWM in Pd
Martin Peach
martinrp at alcor.concordia.ca
Fri May 26 17:33:42 CEST 2006
Hans-Christoph Steiner wrote:
>
> I just realized the answer to my question about getting positive-only
> voltages from the sound card. The DC filters will probably remove the
> DC offset, therefore, the output voltage on a PWM signal will also be
> centered again on 0, and therefore swing from negative to positive. I
> do remember getting some very low frequencies out of a computer when
> testing speakers. But I haven't actually tested this [pwm~] object for
> electronics. But it would be nice to have a very well implemented
> [pwm~], so its great that this discussion happened.
>
> I did use the [pwm] object with a MIDI-controlled relay box, worked
> quite well at 30-60Hz on a biggish DC motor.
But that sounds like you're sending MIDI messages at a rate determined
by the [pwm], so bandwidth is limited by MIDI to ~1kHz. Better to
program your relay box to do pwm with the pulse width controlled by
MIDI, instead of using MIDI just to turn the motor on and off.
Martin
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