This circuit responds to frequencies from 100 Hz to 3 MHz. We find it in a 90s Radio Electronics. Transistors are general purpose types.
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...