This circuit uses an amplifier from National Semiconductor, uncommon nowadays. The numbers in parentheses are for the second channel. The circuit is suitable for old tape recorders.
This circuit, which uses components still common today, was found in a 1997 documentation. It...
This circuit with its light source was found in American documentation two years 70. Or...
This circuit was found in a Philips documentation from 1966. The circuit provides 1 mW with a...