Common Component Pin-Outs

Trying to remember pin outs for common or garden components can be a real pain.

Listed below are a selection of devices I use often, but remember seldom.

npn1.jpg (3891 bytes)

An extremely handy NPN transistor. Worth keeping a good stock of in the bits box.

Inexpensive yet good for 200mA.

Viewed from below.

pnp1.jpg (3760 bytes)

An extremely handy PNP transistor. Worth keeping a good stock of in the bits box.

Inexpensive yet good for 200mA.

Viewed from below.

555.jpg (5077 bytes)

The ubiquitous timer chip.

Click to download PDF file.(143Kb)

Click here for a fantastic JavaScript component calculator, circuits and timing equations for the 555.

MOSFETs make an excellent alternative to bipolar transistors in many applications. Their use as switching elements is particularly attractive as a small RDSon gives low device dissipation, and being voltage controlled there's less power wasted in heavy base drives as with low gain power transistors. They're simple to use, but I find trying to remember how to connect P channel types almost impossible! Purists will argue the toss over switching losses and the like, but that's another story.

nchann.gif (1680 bytes)

N Channel e.g. IRF640

Load is on for VGS +ve
Load is off for VGS -ve

In other words, connecting the gate to +ve turns on the load. Connecting the gate to 0v will turn off the load (take care not to exceed VGSMAX !) Drain current is considered to be positive.

pchann.gif (1658 bytes)

P Channel e.g. IRF5305

Load is off for VGS +ve
Load is on for VGS -ve

In other words, connecting the gate to +ve turns off the load. Connecting the gate to 0v will turn on the load (take care not to exceed VGSMAX !) Drain current is considered to be negative.

	*Remember: Input is always positive* with respect to common!**
	*Remember: Input is always negative* with respect to common!**