Re: PWM motor control from USB I/O board [TANKS]

[Joe Sommer <anvilus9-at-adelphia.net>]

Doug,

At 03:54 AM 5/5/2006 +0000, dwconn404-at-comcast.net wrote:
>This USB board has open collector relay drivers built into the DO 
>channels. I think they'll sink 50ma per channel, but I don't have the 
>specs handy.

Standard VF4 automotive relays have 12 V, 90 ohm coils
that draw about 130 mA.

I recommend using 150 mA opto-isolators between your DO channels
and the relay coils to prevent inductive spikes from getting into your USB
and PC.  If your DO channels are already isolated, you could simply drive
medium size transistors to power your coils.

>  The PWM is open collector, too, but it's easy to modify if that won't 
> work for the SSRs. This thing may actually be a good option for WiFi 
> based motor speed control.

D1D40 SSRs are giant opto-isolators so your USB PWM channels can drive them 
directly.

Joe



**********************************************
Joe Sommer, Anvilus Machine Works
2378 Nantucket Circle, State College, PA 16803
814.234.4773     anvilus9-at-adelphia.net
http://www.anvilus.com