Stealth Blinky

On 6/8/2011 7:17 AM, 1 Lucky Texan wrote:
> On Jun 7, 5:25 pm, D Yuniskis<not.going.to...@seen.com>  wrote:

>> If stuck with a monochromatic LED, you can duty cycle modulate
>> to get a "signal" that someone knowing what to look for can
>> easily detect -- yet, to others, is nonexistent.  E.g., at startup,
>> run LED at 100% for 1.0 second (or some nice easily recognizable
>> duration).  Then drop down to ~80% for your "normal" indication.
>>
>> The drawback of this approach is that it isn't static -- you need
>> to see the processor coming out of reset in order to sense the
>> change in intensity.  (you could also modulate the duty cycle
>> with a very low duty cycle square wave so the lamp briefly
>> brightens periodically)
>
> A steady-state full intensity duplicate right next to the 80% one
> would give you enough contrast.

Yes, but that adds a component just to give you a "reference"
(I think the point is to get as much information out of the
least componentry)

> I wonder if cellphone cameras could 'see' an infrared LED? The
> customer would see nothing, but your phone could be used to
> troubleshoot/confirm operation.

Yes, most digital cameras will (though I can't speak for all!).
But, an Ir LED doesn't tell the customer "power is on", etc.
In fact, it might result in more support calls:  "The power
indicator (that *must* be what this thing does, right?) on
my Wonkerator8000 doesn't light up!"

Op 08-Jun-11 16:17, 1 Lucky Texan schreef:

> I wonder if cellphone cameras could 'see' an infrared LED? The
> customer would see nothing, but your phone could be used to
> troubleshoot/confirm operation.

All cellphones with camera I have had so far were able to see IR LED's. 
It is a great diagnostics tool to check IR remotes.

On Jun 8, 9:58=A0am, D Yuniskis <not.going.to...@seen.com> wrote:
> On 6/8/2011 7:17 AM, 1 Lucky Texan wrote:
>
> > On Jun 7, 5:25 pm, D Yuniskis<not.going.to...@seen.com> =A0wrote:
> >> If stuck with a monochromatic LED, you can duty cycle modulate
> >> to get a "signal" that someone knowing what to look for can
> >> easily detect -- yet, to others, is nonexistent. =A0E.g., at startup,
> >> run LED at 100% for 1.0 second (or some nice easily recognizable
> >> duration). =A0Then drop down to ~80% for your "normal" indication.
>
> >> The drawback of this approach is that it isn't static -- you need
> >> to see the processor coming out of reset in order to sense the
> >> change in intensity. =A0(you could also modulate the duty cycle
> >> with a very low duty cycle square wave so the lamp briefly
> >> brightens periodically)
>
> > A steady-state full intensity duplicate right next to the 80% one
> > would give you enough contrast.
>
> Yes, but that adds a component just to give you a "reference"
> (I think the point is to get as much information out of the
> least componentry)
>
> > I wonder if cellphone cameras could 'see' an infrared LED? The
> > customer would see nothing, but your phone could be used to
> > troubleshoot/confirm operation.
>
> Yes, most digital cameras will (though I can't speak for all!).
> But, an Ir LED doesn't tell the customer "power is on", etc.
> In fact, it might result in more support calls: =A0"The power
> indicator (that *must* be what this thing does, right?) on
> my Wonkerator8000 doesn't light up!"

Just label it 'warning light'.

On 6/8/2011 11:03 AM, 1 Lucky Texan wrote:
> On Jun 8, 9:58 am, D Yuniskis<not.going.to...@seen.com>  wrote:

>> Yes, most digital cameras will (though I can't speak for all!).
>> But, an Ir LED doesn't tell the customer "power is on", etc.
>> In fact, it might result in more support calls:  "The power
>> indicator (that *must* be what this thing does, right?) on
>> my Wonkerator8000 doesn't light up!"
>
> Just label it 'warning light'.

Hmmm... you don't, by chance, work for MICROSOFT???  ;-)
(sure sounds like the way *they* would "solve" the problem.
And, then, file for PATENT PROTECTION on their innovative
new idea!  :-/ )

In message <1Kqdncn027VuGnPQnZ2dnUVZ_s2dnZ2d@web-ster.com>, Tim Wescott
<tim@seemywebsite.com> writes

>So, is it too weird to blink the lights under software control at 50 or
>100Hz?  They'll appear to be steady to the naked eye, but if you wave
>the instrument in the air (it's hand-held) then a running processor
>will show you a train of dashes, while a dead one will show you a solid
>streak.

 Another trick would be to wave your hand, fingers spread in front of
the 100Hz LED. You will get a stroboscopic effect and the LED will seem
to blink slower.
-- 
 To reply, my gmail address is nojay1              Robert Sneddon