Subject:
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Re: Homemade LED Bricks
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 12 Nov 1999 03:39:49 GMT
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Original-From:
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"Keith Miller" <kmiller@talon.net>
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Viewed:
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858 times
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grrr.. I flubbed..
instead of r = .01/9 make it r = 9/.01
----- Original Message -----
From: Keith Miller <kmiller@talon.net>
To: <lego-robotics@crynwr.com>
Sent: Thursday, November 11, 1999 10:23 PM
Subject: Re: Homemade LED Bricks
> basicly.. it's i*r=v where i = current in amps and r = resistance in ohms
> and v = voltage in volts..
> so..
> If we want to find out the resistor's value.. we re arrange it like so..
> r = v/i
> so 10 millamps (typical led current) = .01 Amps..
> And at 9 volts it becomes
>
> r = .01/9
> r = 900 ohms
>
> there..
> <G>
> I went to votech for electronics.. <G>
>
>
> ----- Original Message -----
> From: C S Soh <cssoh@singnet.com.sg>
> To: <lego-robotics@crynwr.com>
> Sent: Thursday, November 11, 1999 10:04 PM
> Subject: Re: Homemade LED Bricks
>
>
> > Michael Gasperi wrote:
> >
> > > David Johnston <lego-robotics@crynwr.com> wrote in message
> > > news:LOBBJCENKNHFLCKICLNNIEODCAAA.djohnston@tinet.ie...
> > > > not being an electronic engineer, what is "appropriate"?
> > >
> > > I'd say 330 Ohm 1/4 Watt.
> >
> > Er, 330 ohm may be ok for the usual transistor type circuit where the
> > nominal supply voltage is 5 volt, if my memory has not failed me.
> >
> > It may be a bit low, I think, for the RCX where the nominal voltage is 9
> > volts which is almost double of 5 volt. So maybe a resistance of 680
> > ohm would be more "appropriate"?
> >
> > But then I'm not an electronic engineer either. Just wanted to be sure.
> > --
> > C S Soh
> >
> > http://web.singnet.com.sg/~cssoh
> > ... where air is power
>
>
>
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Message is in Reply To:
 | | Re: Homemade LED Bricks
|
| basicly.. it's i*r=v where i = current in amps and r = resistance in ohms and v = voltage in volts.. so.. If we want to find out the resistor's value.. we re arrange it like so.. r = v/i so 10 millamps (typical led current) = .01 Amps.. And at 9 (...) (25 years ago, 12-Nov-99, to lugnet.robotics)
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