Found in a Popular Electronics from the 90s, this circuit is intended to measure the harmonic distortion of an audio signal. The circuit can be tuned between 970 and 1030 Hz.
P1 on this Radio Shack circuit is a 6 V lamp with current up to 500 mA depending on Q2. The...
This simple touch alarm, found in a 1995 documentation, uses common components and a triac to...
With the micro voltage regulator shown in the figure, we can design a power supply for small...