| Name | Link | Category |
|---|---|---|
| Schematics For Free | http://www.schematicsforfree.com/ | Reference & Tools |
| Bitsavers | https://bitsavers.org/ | Reference & Tools |
| Instructables | https://instructables.com/ | Open Source Projects |
| Electronics-Lab | https://electronics-lab.com/ | Reference & Tools |
| DiscoverCircuits | http://discovercircuits.com/ | Reference & Tools |
| Falstad Circuit Simulator | https://falstad.com/circuit/ | Reference & Tools |