This bidirectional circuit was found in an American documentation from the 80's. The LEDs are common red, and the resistor is calculated according to the formulas next to the diagram.
This oscillator can be used to produce signals ranging from a few kilohertz to approximately 10...
This circuit measures alternating voltages on 5 scales and its accuracy depends on the tolerance of the...
This circuit was obtained in a 90’s Popular Electronics. The operators admit equivalents such as...