This circuit is from a 1974 publication by Motorola. The unijunction may be 2N2646 and bipolar BC558 and BC548. The pulse duration depends on the capacitor.
The operational amplifier used in this application is not the most common today. The circuit is...
This basic blocking oscillator configuration was obtained from a 1954 transistor book. The...
This circuit appears elsewhere on this site, but from different sources. Using the LM3900, we find this...