[Noisebridge-discuss] Shameless Frantisek Impersonation (Re: LED Calculations help)

Christoph Maier cm.hardware.software.elsewhere at gmail.com
Mon May 21 12:20:53 PDT 2012


Another Frantisek Apfelbeck impersonator here, hailing from Seoul:

For electrical purposes, these circuits are not LEDs, but integrated
two-terminal blinkylight integrated circuits.
As such, they have built-in current limiting and can be operated directly
off a battery.

As they apparently don't have a datasheet that is 1. not in Chinese and 2.
available,
it might make sense to sacrifice one or two of the LEDs by hooking them up
to a laboratory power supply that displays both voltage and current,
then to ramp up the voltage from 1.0V in small increments until the LEDs
get fried, while measuring current and observing brightness.

If I recall correctly, Jimmie Rodgers gives away these blinky LEDs with a
battery [http://en.wikipedia.org/wiki/CR2032_battery] when he gives basic
soldering instruction.

Greetings from Seoul,

... Frantisek?

On Mon, May 21, 2012 at 11:48 PM, jim <jim at systemateka.com> wrote:

>
>
>    What kind of LEDs? Different types have differing
> voltage drops and current ranges.
>
>
>
> On Sun, 2012-05-20 at 22:16 -0700, Phil Spitler wrote:
> > Hi,
> > For simple LED projects, I usually use an online LED calculator to get
> > the values for the needed resistors.
> >
> >
> > I have just ordered some LEDs online but the specifications don't list
> > the forward voltage, just the current draw.
> >
> >
> > http://www.adafruit.com/products/679
> >
> >
> > How would I figure out how to power the LEDs and what resistors to
> > use?
> >
> >
> > I am thinking of using 10 LEDs and having them all powered, all the
> > time.
> >
> >
> > I would love to know how to calculate my needs.
> >
> >
> > Any ideas?
> >
> >
> > Cheers.
> >
> >
> > Phil
>


> > Phil Spitler |   Associate Creative Director  |  Bonfire Labs |  t :
> > 415.394.8200  |  c : 415.571.3139  |  Bonfirelabs.com
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>
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