This circuit indicates when a rain is acidic by monitoring its pH. The circuit is from a 90s RE Experimenter Handbook. Some components used can be difficult to obtain today.
This isolated shield is from an old documentation, making use of an operational one of the time. It...
We found this transmitter circuit in a 1990s spy book. The coil data is provided along with the...
In this circuit we have the way to use common diodes to obtain low regulated voltages in a single...