simple laser pov projector wiring - uln2003a

[tomas]

hello
on my first arduino project i will make a simple pov (laser pov)
the first stage is to get a laser led(s) working from arduino out pins.
so i set up a breadboard with uln2003a darlington chip , and connected
the board as shown in this link:

http://tomsofer.googlepages.com/home

the laser led is working when powered directly from 5v out but not when
used through pin 13.
also I should ask for directions about current limiting resistor ,
though it seems there is one inside already (this is a disassembled
laser pointer)

thanks
tom

 

[CheapscateDave]

hello
on my first arduino project i will make a simple pov (laser pov)
the first stage is to get a laser led(s) working from arduino out pins.
so i set up a breadboard with uln2003a darlington chip , and connected
the board as shown in this link:

http://tomsofer.googlepages.com/home

the laser led is working when powered directly from 5v out but not when
used through pin 13.
also I should ask for directions about current limiting resistor ,
though it seems there is one inside already (this is a disassembled
laser pointer)

thanks
tom

The uln2003a will pull pin 16 to a low level when pin1 is high. You
need to connect the + LED to a 5volt source( I would use 4.5 volts to
be safe) and the - side of the LED to pin 16 of the uln2003a. I am not
sure what signal is on Pin 13 from your diagram? I am assuming it is a
TTL signal generated from the attached Arduino.

Dave

 

[tomas]

thanks alot dave