Sep 29, 2026
Desktop Companion v1
Holy grail of capacitors
Power circuit is real for any project. Even though its a simple project, designing a power circuit increases the life span of your project, may make it a bit bulkier though.
Field note
Schematic
Blog in draft
I asked Gemini if I could connect the TP4056 directly to the 3.3V pin of the ESP-32 and it gave me three reasons not to -
BOD detection
The ESP-32 works within a tolerance for the operating voltage. The BOD detector inside the ESP-32 looks for the operation voltage and begins a reset loop, once it finds that its not receiving enough power. The BOD circuit has an internal comparator that has a reference voltage which it compares continuously.
The MCP1700 LDO, has a max current limit of 250mA. The ESP-32 during Wifi transmission burst can draw current upto 500mA, and so by adding a 100uF capacitor in parallel with the 3.3V rail and ground, it acts as a reservoir to fill in this power demand.
Voltage sag
The PCB traces introduces inherent and unwanted inductances through the path to the LDO, and during Wi-Fi transmission burst, there can be a possibility that the input voltage at the terminals of the LDO, drops below the dropout voltage. A 1uF capacitor between the input terminals makes sure that a constant voltage is maintained.