Found in Philips' 90s documentation, this small source can use modern transistors like the BD135 for TR4 and the BC series for the rest.
This circuit is from the 1983 Intersil Databook. The ADC0801 and 0804 are low-cost AD converters. They...
This circuit uses only two transistors, the first being low noise, being indicated for dynamic...
This circuit divides the frequency of a signal by two. The circuit is found in the May 1977 issue...