This circuit was found in a Popular Electronics from the 90s. The effect circuit uses components that are still common today. In fact, the circuit has only 3 channels of 12 LEDs.
This 1967 Philips circuit recognizes a light signal (visible or infrared) modulated by tone. The...
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
This is the receiver for the previous circuit transmitter. Similarly, no information about the...