This RF amplifier step has a dynamic range of 140 dB and can amplify signals from 0.5 to 40 MHz. FET is old, but modern equivalents can be used.
This very low power amplifier is designed by Amperex for hearing aids. It is based on TAA370 which is...
When the sensor, an ordinary photo-transistor, receives light, the relay closes its contacts. The...
This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and...