Re: Driving servos from a PC

The message <4udf3dF17ms4aU1@xxxxxxxxxxxxxxxxxx>
from Pete Verdon <news@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
contains these words:

As part of a construction project for a charitable event, I need to
build a number of big analogue dials (like an old-fashioned voltmeter)
controlled by a series of PCs (each computer drives two dials). Accuracy
isn't critical, but I do have a fairly strict budget restriction.

One possibility seems to be to use an RC servo to move a big cardboard
needle. I've not used servos before, but a little research suggests that
the required position is commanded by altering the pulse width of a ~5v
50Hz square-wave signal a little either side of 2ms.

As I said, I don't have much of a budget. I also have limited
electronics knowledge. But is it totally unrealistic to consider
controlling these servos via a soundcard output? I envisage putting one
dial on each of the left and right channels, and getting the card to
spit out an appropriate wave-form to each of them. I realise this won't
be a proper square-wave, but am I likely to get close enough?

What else have I missed? Do you have another (cheap) suggestion, whether
involving servos or not?

Thanks,

Pete

Hi Pete

I stand to be corrected but I don't know of any simple way that you can
interface a servo to a sound card, let alone two.

servos would be good but might be a little over kill, why only two to
each PC? Could you use one PC for upto eight?

if so some ideas to make your own servo controller at:

http://www.rentron.com/SerialServo.htm

or buy

http://www.britishrobotics.com/pictures/BRCandice/BR650290Desc.htm

I have the original SSC version two at http://www.seetron.com/ssc.htm

Cannot for the life of me remember where I bought it in the UK, and have
also built the first one, both are ideal for controlling multiple servos
and very easy to programs for the serial ones. Cannot comment on the usb
ones you may find.

I will try and remember where I bought the kit from, hope this helps

Pete
.

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