This circuit with 24 dB per octave attenuation was found in the November 1973 Radio Electronics magazine. The components are for 1 kHz but can be recalculated for other frequencies.
This circuit was found in an American documentation from the 80's. The components are from that...
The circuit shown is from the Texas Instruments optoelectronics manual. It is intended for audio...
This circuit drive an LED with constant current determined by the values of the resistors of 10...