[Shotimes] how do flashers work?

[James F. Ryan III]

> I appreciate the lesson, but I think you just said that as a light, the
> LED is very LOW resistance, and thus my first statement would be
> correct.  Yes? No?

If the current-limiting resistor wasn't there, the low resistance of the
forward-biased diode would allow a butt-load of current to flow, and yes
that would give you a very bright light.  BUT, the diode is "delicate" and
can not take a lot of current (hence the current-limiting resistor).  If you
ran the LED without the current-limiting resistor, you probably wouldn't see
ANY light because it would damage itself instantly.  The same way a
filament-type bulb would instantly burn out if not kept in its oxygen-free
environment.



----- Original Message ----- 
From: "Donald Mallinson" <dmall@mwonline.net>
To: "James F. Ryan III" <av8r567@optonline.net>
Cc: <shotimes@autox.team.net>
Sent: Thursday, July 07, 2005 3:51 PM
Subject: Re: [Shotimes] how do flashers work?


> I appreciate the lesson, but I think you just said that as a light, the
> LED is very LOW resistance, and thus my first statement would be
> correct.  Yes? No?
>
> Don
>
>
> James F. Ryan III wrote:
>
> >>Then please help me understand.  LED's put out much more light with a
> >>lot less electricity.
> >>
> >>
> >
> >Absolutely correct.  LED's are MUCH more efficient at converting heat
into
> >light than their incandescent counterparts.  That's just technology, my
> >friend, not black magic.
> >
> >
> >
> >
> >
> >>They also require a resister in-line to make them equal the resistance
> >>of the older incandescent bulb.
> >>
> >>
> >
> >No.  They require a resistor to limit the current so they don't damage
> >themselves.
> >
> >
> >
> >
> >
> >>If they have much higher
> >>resistance, then why do they light up brighter and quicker with less
> >>juice?
> >>
> >>
> >
> >You struck upon the very definition of a SEMI-conductor - a device that
can
> >act as both a conductor and an insulator (but not at the same time).
> >Normally it has a very HIGH resistance and acts like an INSULATOR.
However,
> >when you forward-bias the device (connect + battery to + lead of diode,
> >and - battery to - lead of diode) it will magically become a CONDUTOR at
a
> >very low voltage of approx 0.7V.  Now the LED/diode has a very LOW
> >resistance and must be protected with a properly sized current-limiting
> >resistor.
> >
> >
> >
> >I thought the higher the resistance, the higher the ohms of
> >
> >
> >>resistance?
> >>
> >>
> >
> >Yup.
> >
> >
> >
> >
> >
> >>Just asking
> >>
> >>Don
> >>
> >>James F. Ryan III wrote:
> >>
> >>
> >>
> >>>>The LED's have a much lower resistance to electricity as I understand
> >>>>it, thus it is like opening up a water faucet from a slow drip to
> >>>>flood.  Things move faster!  :)
> >>>>
> >>>>
> >>>>
> >>>>
> >>>LED's have a MUCH HIGHER resistance.  High resistance = not a good
> >>>
> >>>
> >conductor
> >
> >
> >>>= very little current flow.
> >>>
> >>>LED's and diodes are classified as SEMI-conductors (that's an easy
memory
> >>>aid).
> >>>
> >>>
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> >>
> >>
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