This 1977 circuit only allows the solenoid to energize if the right combination of switch positions is selected. The relay is 6 or 12 V depending on the low voltage supply used.
This circuit is from a 1991 publication, but it can be assembled with more modern components. We...
This circuit provides a current given by the components calculated according to the formula next...
Published in Radio Electronics in October 1963, this circuit increases the audio output of a small...