Among the many methods available for air flow detection, self-heated thermal flow sensors are simple, cheap, rugged, and sensitive. They rely on the relationship between airspeed (AF) and thermal ...

The current flow from collector to emitter in the NPN transistor when the positive supply is applied to the base is vital variations between the NPN vs PNP.

There are also certain amplifier configurations that need PNP units. Like an NPN transistor, a PNP can operate in saturation, linear operation, reverse active, or it can be cut off.

Sourcing power means the sensor output supplies a positive voltage when the sensor turns on. This is called a pnp output. The name comes from the pnp output transistors used to control the power.

The transistors used (a 2N3055 npn and 2N2955 pnp in TO-220 packages) are reasonably good choices. They should be placed on a heat sink for good heat dissipation.

There are numerous differences between NPN and PNP transistors, and even though both are bipolar junction transistors, the direction of current flow is the name of the game.

In this paper, a CMOS temperature sensor using cascaded PNP transistors was designed and measured. The commonly used band gap reference current source, which used bipolar junction transistors (BJTs) ...

Although valves and pumps exist to control flow in microfluidic channels, they are not easy to miniaturize further for use on nanometer levels, says Berkeley mechanical engineer Arun Majumdar.

This paper presents the first process to allow the embedding of amorphous silicon thin film transistors in surface micromachined polymerMEMS. The presented polymerMEMs fabrication technique embeds ...