Found in an 1868 Mullard documentation this circuit has a dynamic range of 10 Hz to 25,000 Hz. Modern equivalent transistors can be used.
Although the BD135 transistor is not specifically for RF applications, some of them can easily...
This transmitter for modulated radiation can be used as an optical data shield. The maximum...
This ultra-low noise circuit was found in the May 1990 issue of Radio Electronics magazine. The...