This unusual circuit from a Popular Electronics of the 90s uses LED indicators, operating as a bridge. The components used are common. It is based on the tuning of the signal by a PLL.
In this oscillator a phase shift network formed by C1, C2, C3 and R1, R3, R4 determine the fase...
For inductive loads we have the configuration shown in the figure. Note that the optical coupler...
This circuit was found in the Linear Applications Handbook by National Semiconductor. It uses...