AVR-Chat

----- Original Message ----- 
From: "Bernd Felsche" <bernie@innovative.iinet.net.au>
To: <AVR-Chat@yahoogroups.com>
Sent: Wednesday, December 15, 2004 4:06 PM
Subject: [AVR-Chat] Radio servo for analogue indicator?


>
> I'm considering all sorts of low-power options for providing an
> analogue indication (moving needle or bar). Typical ammeters draw
> current and the quantity I want to indicate isn't directly available
> as a current... it's number-crunched. Scale will be semi-log.
>
> At first, I looked at small stepper motors but they're simply
> over-kill.  During my search, I've stumbled across radio-control
> servos... which are quite popular in robotics and the driving
> technology is certainly well known in AVR circles.
>
> The question is; has anybody used these servos for instrumentation?
>
> The accuracy doesn't need to be high; it only needs to provide an
> at-a-glance feel for the operator. The indicator only needs to be
> "accurate" at one point, which could be calibrated at "boot time".
> I expect the AVR controlling the servo to have a table of position
> vs value... with linear interpolation for points inbetween.
>
> Any pointers to useful information such as steady-state current,
> holding torques, etc will be appreciated. I Googled but got around a
> million hits... or none.

How about a voltmeter driven with PWM, or a simple DAC?

I think that the Kawasaki Hayabusa motorbike uses servo motors for the 
speedo and rev counter. When the ignition is switched on and the bike does a 
self-test, both sets of needles rotate rapidly for a few seconds.

Leon