This circuit is from an April 1991 Radio Electronics magazine. The circuit uses power MOSFETs and an integrated circuit from that time.
This interesting constant current source circuit was found in the September 1989 issue of Radio...
This circuit was found in an Electronics World of 1966. It has a range of 5 to 25 000 Hz at 1 dB...
This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now...