Simple robot

Life has become a bit boring, and I had to find ways to make it more fun. That's how a primitive robot appeared, reacting to light. The simplest construction.

And so. The basis of the construction is the technological marvel - the L293D microchip, which is often called a motor driver for a microcontroller. But don't be scared. Not yet. The idea behind the microchip is very simple - it changes the level of the outgoing voltage depending on the level of the incoming signal. And our incoming signal will be... the power source itself, but the current from it will be changed by a light-sensitive element... Well, I think you've read the article at the top.

Despite the primitive idea, novice inventors may experience some discomfort when attempting practical implementation. Here's what I got.

I drew a board, it's not entirely successful, because later I soldered trim resistors, and originally planned for fixed ones, but here it is:

Patient preparation:

After etching the board, I got this miracle:

By the way, I got the L293DD model, which is intended for surface mounting.

I used phototransistors as light-sensitive elements. But they had a very high resistance, so I had to adjust them. Resistors with a value of 300 kΩ were soldered in parallel, and then, for finer adjustment, trim resistors with a value of 200 kΩ were soldered in series.

Now about the construction itself and how to make it all move. I practically had nothing at hand. Therefore, the entire working scheme was attached with glue to a compartment with 4 AA batteries. Two motors from children's toys, successfully salvaged from the nearest (well, from the nearest...=) ) thrift store, were also attached with glue (unexpectedly, right? =) on the diagonals (you need to build the structure in such a way as to place the motors at the maximum distance).

At first I tried to install the motors in the usual position and attach wheels, but even the smallest ones, unfortunately, did not want to work without a transmission. So, in an effort to reduce the hassle of the first construction, I didn't attach anything to the motor pulley. In this case, you need to find the optimal angle and a bunch of other things, but as a result, a perfectly working version turns out. Here's what it looks like:

By the way, the trim resistors were needed to adjust the sensitivity of the robot to different lighting conditions. So far, it's not going smoothly with that - the robot only works properly if the ambient lighting is minimal.

Demonstration of the work (performed in a dark room):