WiFi Remote Controlled Laser Rainbow Maneki-neko

The new parts arrived and I now finished the current revision of the circuit board.

After repairing some minor etching mistakes I tested all features and everything seams to work fine.

The next thing I need to is to figure out how to actually stuff all this into the cat.

I redesigned the board to fit my new battery safety requirements. Now both cells will be charged separately, protective diodes are used and the voltage can be measured be the ESP.

Also I rearranged things. The board is now divided into the power supply at the top, motor control in the bottom left, accessories at the bottom right and the ESP in the lower center. The 3.3V and 5V regulators are now in parallel and not cascaded anymore.

Although I did all that, the board size only increases by 70mm2

After fixing the battery charging circuit, it worked as expected, but the LM317 got quite hot. Also right now my design uses both lithium cell in series without balance charging. This imposes some avoidable safety risks. Also, because of the lack of diodes, the battery would slowly discharge over the adjustment resistors of the LM317.

Because of all that I decided to redesign the charge circuit. The plan now includes two LM317s, one for each cell, protective diodes and a voltage device to make the ESP monitor the battery.

Ok, obviously you have to double check everything, when you order parts at Conrad Electronics.

Instead of 2.7k smd resistors they delivered 200k, so therefore the voltage coming out of the LM317 was way off.

Bodged it now by soldering a 2.7k through hole resistor in place.

Today the parts from Conrad arrived. The cascaded voltage regulator worked without load.

I tested the LM317 battery charge circuit with a 1kOhm load. It didn't work. Maybe there was solder bridge. The circuit will be rebuild on a breadboard an tested again.

NodeMCU provides nice file function which make it possible to store and read file to and from the internal file system.

Someone on Github provided a python script for down and uploading files. The problem was, that it had two flaws. The first thing is that it wants to take the whole file path as file name on the ESP. The other thing is that you have write the flag in the correct order...

So I started to write an own script. It is not finished yet, but the upload functionality already works.

This is my first project involving the ESP. I wanted to try I learn something new, so I installed NodeMCU, because was very unfamiliar with Lua.

Downloading and flashing the firmware was surprisingly easy. I even used the cloud service to build "my own" with only the modules I wanted. Maybe in the future I will compile it on my own device. The main reason to do that is -except for safety reasons- the possibility to make the ESP AP behave like a captive portal, so every DNS request would lead to the TCP server running on the ESP.

The first thing I wanted to do is mounting the lasers in the cats hat. The difficult part is getting them as parallel as possible. Mounting them both one at a time would have been a fairly difficult way, because I didn't want to drill the head open and I only can operate with tweezers in the cat.

The solution was to measure the distance between the eyes, mount one contact of each diodes with a stiff piece of wire to a perfboard and an the other contact with stranded wire. Power both both LEDs (I wired them in parallel) and tweak until they are parallel.