Links:
NOTE!: When following any instructions provided by these links always ensure proper safety pre-cautions are taken, as many of the provided instructions are over 70 years old
Microphonic relays from H.P. Friedrichs Homepage
- Digitised version of H.P Friedrichs "Instruments of amplification" -Provides details and explanations on how to make relays, semiconductors and related components from scratch
- A directory of technical manuals published before 1964, useful for research
- Old books on electricity and early electronics
- A site that provides a PDF for the 1913 book 'The Boy Electrician' which I'm told is very good
- A interesting read on how to perhaps make alloy-junction transistors