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 circuit can be used with common transistors, from general purpose to medium power. The...
This configuration can be found in almost all LM117 manufacturer's manuals. This circuit,...
This circuit was published in Popular Electronics from the 90's. The components are common, as...