We found this circuit in the June 1987 issue of Radio Electronics magazine. With it, it is possible to receive signals from the bands determined by the crystals in a common medium wave receiver.
This circuit makes use of an operational amplifier from the 80's. The circuit can be implemented with...
When the power is cut off, this circuit keeps the flashlight on for a while, allowing it to be...
Using the CK722 this directional photometer was published in Radio Electronics magazine in July...