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.
The short-wired circuit is suggested by National Semiconductor in documentation on the LM3909. The power...
This ultra-low noise amplifier and simple power supply was found in Analog Devices documentation from the...
This touch switch is from a 1978 publication. The circuit should not be powered by a...