Found in an Electronics World of 1969, this circuit causes a light bulb to flash along with the audio signal applied to the input. The circuit only works with incandescent lamps. C can be 47 nF to 220 nF.
The integrated circuit used in this configuration for noise reduction on FM radios is not common...
The presented circuit provides an output voltage proportional to the input current, according to...
The low-pass filter shown in the figure uses two operational amplifiers with JFET at the input to...