This circuit is from an Electronics Now from the 90s. The circuit uses a power integrated circuit from the time that must be equipped with a heatsink. The power supply is 18 V.
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...