This circuit is based on a regulator component that consists of a transistor and zener in the same package. The circuit can be designed with the equivalent discrete configuration. The current is 200mA.
The sensor in this circuit is a BA315 diode. Other diodes can be experimented, but this is one...
This circuit tunes MW radios to apply the signal to a good audio amplifier. The circuit is from an...
This circuit can use both separate LEDs and a common cathode display when one segment indicates...