Infrared modulated transmitter (CB7247E)

This simple Philips circuit from the 1960s can use any general-purpose transistor. The signal is modulated at 2.7 kHz.

Shutdown After 60 Seconds using an UJT (CB12335E)
In this circuit of a 1968 publication the unijunction may be 2N2646 and the transistor BC548. The...
Zener triggering (CB21472E)
The purpose of this circuit is to improve a trigger circuit using a zener diode. The circuit was...
Crystal Radio with filter against Jamming Station (CB934E)
This interesting circuit of the American publication Electronics Handbook Volume XIII 1993 shows a...