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1
vote
2answers
1k views

Using a relay to switch between 230VAC inputs

I have two mains power inputs (in case one fails, the other is likely to still work), but the device only has one power supply, so I decided to use a relay to switch between the inputs (the device ...
13
votes
3answers
2k views

Dual-SIM phone, do they use 2 GSM modules ? Anyone has high level schematic?

As an slight extension of my project, I am trying to see if I can improve connectivity resilence by using a dual-SIM approach. Dual-SIM phones (or Tri-SIM, quad-SIM phones) are quite popular in many ...
4
votes
2answers
178 views

Operation without power: Passing analog video

Okay, the title sounds odd, I'll admit. I need my project to work without power. That is, a complete power failure may happen, and no additional power (such as a battery or supercap) is available ...