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Amazon.com: Geekworm Raspberry Pi 4 UPS with Power Adapter, X703 UPS Shield + 20W Type-C 5V 4A Power Adapter for Raspberry Pi 4 Model B : Electronics
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Detecting and controlling mains voltages with a Raspberry Pi or Arduino | Experiments using a Raspberry Pi and solid state relays (SSRs) to sense the presence of mains electricity and switch loads
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