Light Following Robot Does It The Analog Way
If you wanted to build a robot that chased light, you might start thinking about Raspberry Pis, cameras, and off-the-shelf computer vision systems. However, it neednโt be so complex. [Ed] of [Death and the Penguin] demonstrates this ably with a simple robot that finds the light the old-fashioned way.
The build is not dissimilar from many line-following and line chasing robots that graced the pages of electronics magazines 50 years ago or more. The basic circuit relies on a pair of light-dependent resistors (LDR), which are wrapped in cardboard tubes to effectively make their response highly directional. An op-amp is used to compare the resistance of each LDR. It then crudely steers the robot towards the brighter light between turning one motor hard on or the other, operating in a skid-steer style arrangement.
[Ed] then proceeded to improve the design further with the addition of a 555 timer IC. Itโs set up to enable PWM-like control, allowing one motor to run at a lower speed than the other depending on the ratio between the light sensors. This provides much smoother steering than the hard-on, hard-off control of the simpler circuit. [Ed] notes that this is about the point where he would typically reach for a microcontroller if he hoped to add any additional sophistication.
In an era where microcontrollers seem to be the solution to everything, itโs nice to remember that sometimes you can complete a project without using a processor or any code at all. Video after the break.
youtube.com/embed/ikTkOXu1th4?โฆ
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hackaday.com/2026/01/28/light-โฆ