"Greg Mayman" bravely wrote to "Mike Ross" (27 Aug 03  08:37:00)
 --- on the heady topic of "WATTS UP? KILOWATT-HOUR M"

 -=> Mike Ross said to Greg Mayman
 -=> about "WATTS UP? KILOWATT-HOUR M" on 08-25-03  08:11.....

 MR> Those displays were a sort alphanumeric. The word digital only applies
 MR> but when some kind of computer counter logic circuit is used.

 GM> Nope, digital in this case means "using digits". A digital clock
 GM> displays the time in digits, 0, 1, 2, 3, etc.

 GM> The other type is an ANALOGUE (or ANALOG) clock where the
 GM> movement of a hand around a dial is analogous to the smooth and
 GM> continuous passage of time.

 MR> Otherwise  things like mechanical odometers would be considered
 MR> digital.

 GM> Which of course they are ;-)

Okay, then fetch us a 74LSxx wheel gear... hehehe!
(or a shubbery... we are the knights who say NI!!!)


 GM> Yes, I have just built up one of Dick Smith's kits, for an LED
 GM> torch using a white LED. The interesting part was the electronic
 GM> circuit that allows it to run from a single 1.5v cell, although
 GM> the LED needs about 3.5v or so.

Voltage multiplier or is it one of those led flasher ic's? Reminds me,
in college when I was learning about switching regulator circuits, I
made a flyback multiplier that worked as was taught to design. Then I
had the brain storm to feed back the output voltage to the power supply
through a diode gate. I applied power and the voltage just kept climibng
and climbing, until I was left with a large mushroom cloud of smoke in
the middle of the lab. I don't remember quite what I did in the circuit
but I haven't repeated it since. The teacher seemed to be impressed by
my random modifications to the lab circuits and gave me a passing mark
at the end of the semester. Oh, well... :-)


 GM> It is really brilliant, IMO a lot more light than the original 3v
 GM> bulb, and for only a third the current!

 GM> I bought it three or four months back for about $27. Last month
 GM> they were on special at $17 IIRC.

 GM> Ain't that always the way? 

This led cost $1.75 at the surplus store. Indeed it drops about 3 volts
at about 10mA. I think it could go to 20mA though but I left it at 10mA
for longevity. It replaces the tiny lens in my little nephew's HO
locomotive perfectly. It really lights up the track in the dark and as a
bonus the brilliant beam is spot on realistic. ;-)

 Mike
 ****

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