Friday, August 21, 2020

invisible backlight

Gherkin with 3mm 940nm IR LED backlight

Installed 30 IR LEDs into a regular Gherkin with MOSFET driven backlight circuit. 940nm wavelength light is not visible to the human eye.

I am running this as an IR remote control as described here. While the light is diffused and not directional, it is so bright that it works as long as there is line of sight to the TV.

I used a modified Canon Powershot camera with the IR filter removed to take this picture. These were cheap LEDs I got off eBay, and you can see they aren't very consistent in brightness.

The keycaps are translucent white DSA profile.

Regular 3mm LEDs can fit under some switches. The white bottom RGB style Gaterons with the large cut out on the bottom work. It is a tight fit, and it makes it very difficult to remove the switch as the LED is pressing against the clip mechanism. White bottom Kailh box switches without click bars also work. It is easiest to solder the LEDs with the switch holding it in place.