This circuit is from a manual from the 80's and the operational one used, uncommon nowadays, can be replaced by a modern equivalent. The power supply must be symmetrical.
This circuit activates a relay that has a lamp as a load. The circuit is from a Radio Electronics from...
This circuit was found in an English publication from1979. The circuit can be assembled with a...
An oscillator whose frequency can be adjusted between 500 Hz and 5 kHz with the use of a...