The two types of standard transistors are PNP and NPN which differs in circuit symbols. The layers of semiconductor material used to make the transistor are denoted by the letters. To keep a straight ...

This 2-bit adder was a lot of work to build. It uses a total of thirty-six 555 timers and it does have the option of adding or subtracting numbers. It’s a rather unorthodox use of the part, depending ...

The transistor is probably the most important invention in electronic engineering and the basis for nearly all integrated circuits (ICs). The transistor is a three-terminal electronic device that can ...

In the early days, PNP bipolar transistors were common, but the bulk of circuits you see today use NPN transistors. As [Aaron Danner] points out, many people think PNP transistors are “backward” but ...

A previous Design Idea describes a circuit that uses an astable multivibrator to drive an LED (Reference 1). The circuit in Figure 1 uses a simpler alternative approach. The circuit uses a 2N3904 NPN ...

A versatile signal-conditioning circuit for use with with programmable logic converters or controllers that can accept only one input polarity. Matching a sensor interface with a programmable logic ...