This amplifier was found in a 1970s documentation. Darlington transistors can be replaced for modern equivalents of at least 80 V x 2 A, equipped with good heat sinks.
This circuit is from 1985 documentation. The integrated circuit is not very common today, but...
This power supply is protected from shorts in the load. The BD135 must be mounted on a heatsink...
This receiver for the police band, which at the time was 45 MHz, was found in a publication by...