💬 backup power auto-switch circuit

[openhardware.io]

https://www.openhardware.io/view/32979/backup-power-auto-switch-circuit

[NeverDie]

Sounds interesting. Please post the schematic as well.

[Abd AlHaleem]

@NeverDie of course, I'll add it now

[Abd AlHaleem]

@NeverDie I tried to add it, but it seems "kicad_sch" extension isn't supported now

[NeverDie]

@Abd-AlHaleem You have three options:

1. Print it as a .pdf file. You can upload those; or,
2. Compress the kicad file as a .rar file, but not a .zip file. That will also upload.
3. Best option: Archive the kicad project (as a .zip file by default), and then compress that as a .rar file. That way you can upload the entire kicad project without it being rejected.

[NeverDie]

Thanks for posting the schematic. Just an observation, not a criticism: it looks as though the output voltage will sag down to the level of the logic-LOW threshold of your NOR gate before the battery voltage takes over. Depending on what the load is, maybe that's a non-issue. If, on the other hand, it turns out to be an issue, you could perhaps use a voltage divider to trigger the switch-over with less of a voltage drop seen at the load. In either case, I like the simplicity of the circuit.

[Abd AlHaleem]

@NeverDie
Based on my simulation and testing it's not a problem, yet I can look at it and check it's transient response.