This 10 A solid state relay was found in a 1980s documentation. It can work as a shield and implemented with modern equivalent transistors.
The transistor of this remote preamp can be the BC549. We found this circuit in a 1976 technical...
Although it is a common configuration today, these circuits were taken from an old publication. The...
We found this circuit in a 1982 publication. This source allows an adjustment of the output...