This circuit is from Motorola's 1990 Linear Databook. We can implement it with other operational amplifier. The power supply must be symmetrical.
This circuit with only one transistor was obtained in an old English documentation and can be...
This circuit uses a transistor as noise source and a 741 IC as amplifier, sourcing a high...
This circuit uses an LED (called SSL) to regulate current in a configuration with complementary...