# LED Array Power Source

Discussion in 'Electronic Design' started by James Roberts, Dec 1, 2003.

1. ### James RobertsGuest

I wish to power the below LED array:

http://www.sunbriteleds.com/images/pdf/SSP-LXC206650B.pdf

for continuous use with maximum brightness, without burning
out the LEDs.
I am curious, what would be someone's recommendations for
voltage and current ratings on an AC adapter, as well as
the resistor value?
I will probably use a standard wall wart, regulated, at
a common voltage and current rating.
I could experiment, but I don't want to blow \$30 on a
paperweight.
James Roberts

2. ### BanGuest

James Roberts wrote:
|| I wish to power the below LED array:
||
|| http://www.sunbriteleds.com/images/pdf/SSP-LXC206650B.pdf
||
|| for continuous use with maximum brightness, without burning
|| out the LEDs.
|| I am curious, what would be someone's recommendations for
|| voltage and current ratings on an AC adapter, as well as
|| the resistor value?
|| I will probably use a standard wall wart, regulated, at
|| a common voltage and current rating.
|| I could experiment, but I don't want to blow \$30 on a
|| paperweight.
|| Thank you for your time.
|| James Roberts

If you use this current source, you do not necessarily need a stabilized
supply. The total current is a bit more than 250mA. With the multimeter you
can measure the emitter voltage and then calculate the resistor for exactly
300mA, or whatever your array allows. The red LED is not only a voltage
reference but serves as a remote indicator too.
Build the circuit and then test it with a 33R/5W resistor instead of the
array. With 300mA the voltage should be 9.9V across the resistor.
Choose a wallwart of 500mA 12V at least. The transistor can be any NPN-small
power type of Ic=1A, Pt=1W in free air and hfe>100.

+---------+-------o+13...17V
| |
.-. o+
| | LED-cluster
750| | o-
'-' |
| |/
1.9V +-------| BD135-16
| |>
| |1.2V
| .-.
red LED(V) | |
- | |4R7/1W
| '-'
| |
+---------+-------o GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

4. ### Spehro PefhanyGuest

Be sure to derate the operating current to maybe 200mA total to allow
for Ta>25°C.

Best regards,
Spehro Pefhany

5. ### Spehro PefhanyGuest

The data seems a little.. sparse. What's the principle of operation of

Best regards,
Spehro Pefhany

6. ### Peter LowrieGuest

Gee, thanks Spehro.
PWM, thermocouple, current shunt. If you care to email me I would like to
provide more detailed help.

Kind regards
Peter Lowrie