This sensitive touch key appears on this website from other sources. This version was taken from a 90s American documentation. The source must not be of transformerless type.
Found in a Popular Electronics from the 1990s, this circuit uses components from National...
This circuit was found in Motorola documentation from 1968. SCRs can be modern equivalents and the...
Suggested by the 90s ARRL Handbook edition, this circuit aims to reduce or cancel noise at the...