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I am planning to build an electronic fencing scoring apparatus for training purposes in our club (so no FIE certification required, it's a pure hobby project).

For hit indication, I want to use a bunch of colored LEDs in a grid (probably 9-25). However, I have no idea how bright those LEDs need to be. Being for fencing, I have the following use case:

  • Well lit indoor environment (a gym hall)
  • distance of 5-10m
  • wide viewing angle (routinely viewed from ~60°)
  • colors are red, green and white

Are there guidelines or a rule of thumb for the luminous intensity I should use?

Does the necessary luminous intensity change when using multiple LEDs in a grid, or can I just add up the intensities of all LEDs?

As this is the first project where I use LEDs for more than just small status indicators that don't have to be visible from far away, I'm a bit clueless. Even an order of magnitude estimate would be a help.

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  • \$\begingroup\$ You should consider simple experimentation and don't over-think this. By the way, I helped to develop systems to calibrate the brightness and color handling for these OSRAM 16x16 RGB module modules. There are displays like this already available to you and they are designed to work in bright daylight situations for advertising alongside roadways. So they work very well at various angles of view and in broad daylight. \$\endgroup\$
    – jonk
    Commented Jan 14, 2020 at 17:10

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Given the conditions, you are looking into super-bright RGB LEDs. Are you planning on using a light diffuser/guide or just bare LEDs? Light diffuser/guide will look cleaner from afar but also block part of the luminous intensity. It's difficult to quantify how much power you'll need to blast into the LEDs to the actual luminous intensity you'll get in those conditions without a bunch of math, it's probably much easier and fun to figure out by experimenting :)

I'll start with taking a look into Adafruit's RGB lightning offering, they do have strips of RGB LEDs (5050) which are pretty neat and may just be fine for your application, they're pretty cheap so you could order one or two to start with.

I've used SK6812 RGB led for a project and they do have a higher luminous intensity at the cost of more power, they're harder to source though.

Or you could go full-on with these: https://www.adafruit.com/product/2530 Be aware that those may need the heatsink mounted if you use them at high-power.

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