Found in National Semiconductor documentation, this logarithmic meter is powered with a voltage of only 1.5 V. Equivalent operational amplifiers can be tested.
This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent...
This source was obtained from a book on transistors from the 60's. The circuit uses germanium...
This powerful inverter provides a high-quality sine wave signal. I found it in a Radio Electronics issue...