Relays up to 100 mA can be driven by the 555 with the recommended circuit. The circuit is from an article in the September 1992 Radio Electronics magazine.
This circuit uses a transistor as noise source and a 741 IC as amplifier, sourcing a high...
This simple circuit detects when a conductive liquid reaches the sensors. The circuit has no...
With this circuit it is possible to raise the characteristics of a transistor by checking its gain...