My current electronics project is to build a very simple customizable "phone". It is my own idea, with as ultimate goal to learn about microcontrollers and basic electronics.
This is my set-up so far
I managed to interface with the microcontroller, and the voltage transformation circuit seems to works (how do you call this?). The issue is with the Neoway M590 GSM modem. It reboots every couple of seconds. I think this is because the modem draws a peak current when trying to connect to the network a few seconds after starts-up, and automatically shuts down because the voltage drops too low for safe operation. This is why we need the big capacitor there (1000 uF). I power the board with a PSU that can supply more than enough amperage. Communication is via a USB-TTL converter which I connect to a computer.
Please note that in my set-up I have completely eliminated all dependence on the microcontroller and voltage transformation circuit, in an effort to isolate the problem.
The Neoway M590 came with a pre-designed PCB
I have soldered one of these PCBs with a Neoway M590 and had no modem restart issues (after I put in a heavier capacitor).