Patrik Thalin writes:
This device is installed in my home to monitor the usage of electricity. It counts the pulses from the meter and produces a log file with number of pulses and a time stamp that can later be analyzed. The hardware is quite simple. The NodeMCU development kit board with an ESP8266 running the NodeMCU firmware is connected to a phototransistor with an pull-down resistor. The firmware and my lua script seems stable since it has been running for more than 10 days without problems.
The phototransistor used is PT204-6C. It is aimed at the pulse windows on the power meter.
Via the contact form.
Project info at Patrik’s blog.