Using a 1.4~1.6v plus 1.8~2.2v ir leds in series, possible or not. edit:- possible :)

Flashlight Modding and DIY Parts
1

One for the guru’s.
I am going to make an infrared light to soften shadows when taking ir portrait photo’s in full sun, using both 940nm and 850nm leds (and possibly 730nm), trouble is the voltage is a bit weird, could I put one of each in series to make 3.2~3.8V and use any driver for the usual 3~3.5v leds ??
If I can that would mean 2s5p leds with one 7.2v, 7A 3.5A driver.
3W-940nm
DC Forward Voltage (VF): 1.4-1.6V
DC Forward Current (IF): 700mA

3W-850nm
DC Forward Voltage (VF): 1.8-2.2V
DC Forward Current (IF): 700mA

3W 730nm-740nm
DC Forward Voltage (VF): 1.7V~2.4V
DC Forward Current (IF):700mA

Cheers David

Edit, lousy maths :_(

2

The reason I want a fill light is to throw some light into the shadows to lighten them up a bit, I can do it in software but that way also lightens all of the shadows in the image and I want the other dark areas to stay dark, after all a dark sky is one of the attractions of ir for me :wink:
Say hi to my daughter :slight_smile:

As you can see, if I lighten the face shadow I also lighten the sky :cowboy_hat_face:

Cheers David

3

Sure, LEDs in series is no problem other than they will all see the same current and won’t be independently adjustable.

4

Thank you, as they are all the same current I can play with them to get the best voltage for the driver :bigsmile:
Time to sort out the driver and configuration, then buy, then make, wheeeeeeeeeee

Cheers David