This high-impedance headphone circuit was found in a 1990s William Sheets. The power is low, but the high input impedance makes it useful for radio applications.
Found in General Electric documentation from the 1980s, this high speed perforated tape reader...
This circuit indicates when the voltage of a 12 V battery is low. With changes, for example, the...
We found this signal generator circuit in the November 1978 issue of Radio Electronics magazine. The...