Found in a 70s RCA manual, this circuit uses transistors from the era. Equivalent types can be used such as TIP31 for Q1 and BD135 for Q2.
With this luminous remote control, which we found in a 1990 publication, using a flashlight you...
We found this circuit in a 1967 Electronics World. The circuit can be designed to control other...
This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now...