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FromTheRafters

It happens that formulated :
On Thu, 11 Aug 2016 13:44:53 -0700, T wrote:

If a cop dont know, who does? I'm wondering if they go back to zero,
or just keep showing 99?????

Obviously your town doesn't have a Idiot Ordinance. If they did, the
cops would have arrested you on the spot.

+10 and bet the cop had a good laugh later telling his fellow cops about
the idiot at the store

Dudes! This is not a stupid question. This is a fun
question. When did you guys lose your sense of curiosity?

My guess is that the display is driven by a BCD (binary coded
decimal) counter and that it just rolls over to 00.

I know this cop and he's a decent guy. I think I caught him off guard
with this question, but he was having a little fun with it, as well as I
was. But it really is a question which has an answer (somewhere). I
assume those signs have user manuals, and there must be a mention of
using them for speeds over 99. Normal drivers wont experience that
speed, but if those same signs were used at a race track, they would not
work, since many race cars exceed 99mph. Since truck and tractor pulls
uses these signs, I would think that race tracks would use a similar
device, but obviously need one that allows for 3 digits. (I assume they
make a 3 digit one for such uses).

Two and a 'half' digits would be good enough for displaying speeds up
to 199 MPH. It cuts down on the circuitry needed in the display.

I wish I knew the manufacturer of the sign, so i could see if there is a
user manual online.....

Till then, I'll go along with the "roll over to 00" !!!

I would think of it as a two and a half digit display with the 'half'
being left to the reader. It could well be that a log could be kept
which logged speeds well above 100 MPH rather than a rolling over,
leaving only the display limited to two digits.