This circuit is from General Electric documentation from 1970. The transistors can be of general-purpose types, except for the power that can be a BD136.
This circuit generates frequencies determined by R3 and C1. We found it in the Radio Electronics magazine...
The configuration below is suggested by the National Semiconductor Linear Applications Handbook. The...
This charger circuit provides an initial voltage of 2.5 V and when the current reaches 180 mA the...