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Re: RE measuring inductance
Subject: Re: RE measuring inductance
Date: Wed, 07 May 1997 11:21:35 -0700
From: Skip Greiner <sgreiner-at-wwnet-dot-com>
Organization: Greiner, Ltd.
To: Tesla List <tesla-at-pupman-dot-com>
References:
1
Tesla List wrote:
>
> Subject: RE: RE measuring inductance
> Date: Wed, 7 May 1997 08:04:53 +1200
> From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
> Organization: Wellington Polytechnic, NZ
> To: tesla-at-pupman-dot-com
>
> Hi all,
> Here's some workbench experience to add to this....
>
> > From: "William Noble" <William_B_Noble-at-msn-dot-com>
> > To: "Tesla List" <tesla-at-pupman-dot-com>
> >
> >
> > Your comment about 2 volts is suspicious - LED's are diodes which emit
> > when
> > forward biased - depending on the LED, there will be one or more
> > "standard"
> > diode drops in the forward direction - most red LEDs are a single diode,
> > so
> > 0.7 volts will cause them to turn on.
>
> Not true in my experience. I can just perceive a glow at around 1.5V
> for red and a measurement shows that current doesn't seriously start
> flowing until this voltage is reached.
>
> > I have some green LEDs here that take 1.4 volts (e.g. they have
> > 2 diodes in series).
>
Malcolm and All
I have sold LEDs for over 15 years. Over that period I would guess that
I sold devices which were made by at least 15 or 20 different methods
out of 15 of 20 different materials, all having different turn-on
characteristics AND number of diodes. As most people know they come in
colors ranging from blue thru IR. Depending what particular device one
has in hand you will find turn-on voltages ranging from about .5v to
well over 5v. Best thing to do is check the unit before you try to use
it. Once you know the turn on point you can work with it.
Skip