Found in Philips' 90s documentation, this small source can use modern transistors like the BD135 for TR4 and the BC series for the rest.
The coil of this receiver consists of 100 turns of wire 38 to 30 in a ferrite rod and the...
This TTL pulse stretcher or stretcher was found in a 90's EDN. The time constant R x C1 determines...
This circuit was found in a 1968 Motorola documentation. The circuit can be implemented with...