[Robotgroup] Do you have a 15V and 500mA power supplier?

[Paul Atkinson]

PY,

If the LEDs of a petal are in series, then the current is still only 20ma for the petal, so you might only need 100ma total for all 5 petals.

If you can arrange it so that you can use 12V, then I may have a PC power supply you could use, or perhaps even a wall wart that can do 12VDC at 1 or 2 amps.

This link has an LED wizard/calculator that can help you with the connections:
http://led.linear1.org/led.wiz

Paul

Pui Yee Hung <puiyeehung at gmail.com> wrote:  Hi all,


Wondering whether you have a 15V and 500mA  power supplier to spare? (
higher voltage and more current will be even better)The power supplier is
for  a dorkbot project.  Below will describe the idea, your suggestion or
comment is welcome!

This project  has a mechanical flower which is lighted by Leds.  The Leds
are mounted on plexi-glass strips which look like petals. The flower will
have a minimum of 5 petals ( if possible 8 petals). Each petals has 5 leds (
in parallel).  The petals are control by basic stamp II, and connect to ULN
2803 ( High current Darlington).  Each petal is connect to the power
supplier.  The plan is to program the Basic stamp so that each petal can be
lighted up or dim down at different sequence.

In calculating my power supply requirement, I use the following assumption :
Each petal is link in series and power by the power supplier. Each LED has a
voltage drop of 2 V to 3 V( bright white LED).  So for 5 petal, I need 10 to
15 V.The current draw per LED is ~ 20MA.  For 5 petal , 25 LEDs, I need
500mA.

Is this assumption realistic?

IDenise has a design of the petal.I am not attending the meeting today
because of sickness.

Thanks in advance for your help!!!

Py


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