This circuit can activate a powerful lamp or call system when a telephone call occurs. Suitable for hearing impaired or noisy places it was found in American documentation in the 90s.
This circuit with germanium transistors was found in documentation from the 50's. The transistors are...
The circuit presented was found in a documentation from the 1950s, generating a sinusoidal signal...
This circuit was originally indicated as a signal reinforcement step for the previous receiver...