[amsat-bb] Re: AlfaSpid RAS & Predict

Gordon JC Pearce gordonjcp at gjcp.net
Tue Feb 2 23:47:21 PST 2010

On Tue, 2010-02-02 at 11:16 -0800, Ryan Caron wrote:

> Additionally, has anyone noticed the digits on the controller display 
> flickering? Its just a nuisance, but surprising since I'm feeding it 
> from a lead acid battery so there can't be any ripple or rectification.

It may be that they are multiplexed, and driven at a low enough
frequency that the flicker is apparent.  You see this on all sorts of
equipment.  One particularly unusual one was the Ensoniq Mirage sampler
from the mid-80s, where the segment lines were driven from a shift
register and the digit selects for its two-digit LED display (100
parameters, some in hex, and an UP and DOWN button to edit them...) were
driven off an I/O pin.  All of it was handled in software, and when the
sound chip was making heavy demands on its little 6809 brain the display
would dim, then flicker in a kind of "chase pattern"...

Gordon MM0YEQ

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