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 charger for a maximum current of 15 A was obtained from an American 80's schematics. The triac must...
This circuit is from the 1971 Motorola SCR Power Control Fundamentals. The circuit can be made...
This circuit, published in 1988, uses several types of sensors and relays to activate warning...