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Comment by wlievens | Hacker News Reader

Of those, only real time energy usage monitoring is really interesting, I think.

I bought an 'Owl' energy clamp and display from the discount bin at a local hardware store - about £13 ISTR. I made a copy of the rflink (Arduino-based 433MHz rf sniffer/decoder: https://diyprojects.io/how-build-rflink-433mhz-radio-home-ga... - about £20 including ESP8266 wifi link) that decodes the signal from the Owl, my wireless doorbell and that of an outdoor temp/humidity sensor (£6 from Banggood). The board can also send control signals to the rf-enabled mains sockets I have collected over the years (for lights and home appliances).

It's all managed by a raspberry Pi (About £20). The system can also pick up my wireless doorbell, and I am about to add temperature sensors and relays (£25) to my central heating system so everything is automated and controllable from Node-Red and a Web interface. Overall, I will have a private home control system for under £100 and I can view and manage it from my laptop or a VPN link from my phone.

For me, the IoT takeaway is, if you want to be able to trust it, you need to do it yourself. Commercial products seem to always want to sell your data to the highest bidder, aside from the potential firmware security problems.

At least with the Pi, Arduino, etc., you can control what your Things are doing, and have reasonable assurance they aren't doing things behind your back.

I have a Pi graphing outdoor and basement temperature and humidity using rtl433, MRTG, and some scripts, picking up the signals from existing temperature monitors. It's quite a surprise to see how much else is on 433 MHz in my neighborhood, even when using the stubby magnetic mount antenna that came with the RTL-SDR dongle.

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