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 in demonstrations or science fairs. The circuit uses headphones and can...
We found this wiretapping circuit in a publication from the 90s. The circuit allows the cable...
This circuit uses a resonant reed switch at the trigger frequency. The circuit is from General...