This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent components. The transistors may be BC558 and the transformer is obtained from a disused transistor radio.
April 2017 - Texas Instruments bq51222 integrated circuit for chargers and other Qi wireless power...
Using two 567 PLLs, this circuit recognizes two audio tones in sequence providing a signal for a...
This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose...