> > >Then I would suggest you're working with engineers who are not
> > > particularly knowledgable about practical electronics. If they're (say)
> > > mechanical engineers or civil engineers, then no problem. If they claim
> > > to tbe electronic engineers I'd probably dispute that claim.
> >
> > I agree, last year they couldn't even build a set of LED Christmas tree lights
> > without blowing them up, never heard of constant current drive !!! I'm not
>
> Do you own a suitably large LART?
>
> I must have told the story of the 362.8 ohm resistor. In case I haven't,
> it goes like this.
>
> I was working in a lab at a university over here when some final year
> engineering student asked me for a 362.8 ohm resistor 'as there are none
> in the drawer'. I said that I was not suprised, and asked him what on
> earth he needed it for.
>
> The answer? An LED current limiting resistor. Apparently he'd taken the
> well-known formula R=(Vsource-Vforward)/Iforward (which I may add, he
> couldn't derrive), stuck in his PSU voltage, the LED forward voltage and
> typical current form the data sheet and calculated a resistor value.
>
> It took me a long time to convince him that a 390 ohm (which we did have)
> would be fine. As would a 360 Ohm (I think I could have found one of
> those). Or even a 330 Ohm. Heck, a 470 Ohm would have given some light
> output, just a bit dimmer than the data sheet value.
In our incoming test group one of the electrical engineers didn't know
V=I*R. Some of the other electrical engineers didn't have a clear
concept of how a transistor operates. I feel fortunate that our school's
EE program went into the basics in depth and built from there.
--
Eric Dittman
dittman_at_dittman.net
Check out the DEC Enthusiasts Club at http://www.dittman.net/
Received on Tue Jan 01 2002 - 12:00:42 GMT