Using two 741 operational amplifiers, this low-pass circuit has a cutoff frequency of 10 kHz. We found it in an article in the magazine Electronics Now from August 1993.
This circuit is from 1964 documentation but can be easily implemented based on current components....
With this circuit it is possible to observe two low frequency signals at the same time on the...
This medium wave radio works with any general purpose NPN transistor. The diode must be made of...