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.
Unlike the previous circuit, this circuit from Electronics Now, October 1993, has the load...
For the component values used in thisf this circuit, the frequency can be adjusted between 740 Hz and...
We found this circuit in the 1982 Selezione Radio magazine in Italy. The circuit uses an...