Miata Mailing List: October 1999, Message #183

In message <199910012304.QAA06540@hawk.prod.itd.earthlink.net>, Lanny Chambers 
writes:
> On 10/1/99 16:03, Keith Hearn khearn@Legato.COM wrote:
> 
> >There may also be better strategies than a timer since last brake
> >  release for deciding whether or not to blink on any given 
> >  application of the brakes.
> 
> How about this: flash briefly but very rapidly--say, 4 times in one 
> second--but ONLY when the braking system fluid pressure exceeds whatever 
> it takes to decelerate at 0.5G (exact figure open for debate...hopefully 
> somewhere off this list!). After one second the flashing stops in favor 
> of a solid light...or perhaps stays flashing if braking exceeds 0.75G. 
> Whatever.
> 
> This requires no rocket science. In the '50s, Fords used pressure 
> switches instead of mechanical pedal switches to actuate the brake 
> lights, and ours surely weren't rockets! I presume they stopped using wet 
> switches because they became more expensive and less reliable than dry 
> ones.

No offense intended, but Yuck! I'd rather program a microcontroller to
  do it based on input from a mercury switch instead of muck about with
  adding a pressure switch to my brake system. 
  
But that's just me, speaking from a computer geek point of view. :)

Actually, I think if you're keying off of decceleration, you wouldn't
  really need the timer. You'd have the blinker whenever you are braking
  hard, which wouldn't be long. One G is about 20mph per second, and is
  also about what a Miata is capable of doing when braking. That'd only
  be 3 seconds to go from 60 to 0.  Half a G is about 10mph per 
  second, so 60 to 0 would only be 6 seconds. 

I think I'll hook up my G-Tech for a few days and see what kind of
  decceleration I typically do in various circumstances and try to come
  up with a line between "normal" and "hard" braking.

  Keith Hearn
  '99 10AE "Sexy Sadie" the Sapphire Shark
  Milpitas, CA