This circuit also appears elsewhere on this site, obtained from other sources. This is an 80's American schematic book. Instead the lamp can be used white high-brightness LEDs.
This touch switch is from a 1978 publication. The circuit should not be powered by a...
The circuit shown uses the 741 operational amplifier, but lower noise and higher gain equivalents...
We found this zener regulator in a 1978 radio amateur documentation. The operational can be...