LEDs that slowly fade in and out to indicate stand-by mode or the availability of a new message have been made popular by smartphones and other gadgets. To do this is easy enough with a microcontroller and some programming, but can you do it without? So here is the deal
Design an all-analog fading LED circuit and post it on Elektor Labs. Add a short video to show it off. Bonus points will be given for added functionality like adjustable fading speed and duty-cycle.
Each of the projects have a schematic and most of them have videos showing their effect – I’ve included a few of them below. You can see all 15 designs and read more about them here at elektor.
Seen in the lower-left, this fading circuit is based on the NE555:
This circuit can be adjusted while operating and uses the LM324 op amp:
Here’s an intriguing logarithmic fader described as:
Here is an analog dimming circuit for a LED which takes into account the light sensitivity of the human eye (Weber-Fechner-law). For this purpose, the current through which the LED’s rise logarhitmically and drops off again when switched off in reverse logarithm.
This video also went to the extra effort of including credits and a soundtrack. 🙂 Watch:
Here’s a fader circuit based on the LM358:
And lastly perhaps my favorite, a dual-transistor (NPN & PNP) design that can be easily adjusted with a single resistor swap:
Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here: adafruit.com/editorialstandards
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.