Differences

Often you find a transistor, IC or other electronic part and there are some small naming differences, like ATtiny13 and ATtiny13a. You start to wonder what differences are and go to google it. On this page I'm going to post most of the differences I encounter for easy access. Got something to add?, please comment.

ATtiny's

ATtiny13    -
ATtiny13v  - Like the 13, but max. 10Mhz and can run on 1.8 Volt instead of 2.7 Volt;
ATtiny13a  - Replaces ATtiny13 and ATtiny13v, can run on 1.8 Volt and 20Mhz.

See this image below for an overview with the differences between the Attiny13, Attiny2313, Attiny24, Attiny25, Attiny26, Attiny45, Attiny84 and Attiny85. (data from Feb. 2009)

Transistors

NPN - not pointing in
PNP - pointing in

In front of the transistor means (like BC549):
B - Silicon
BC - Small signal transistor ("allround")
BF - High frequency, many MHz (low power)
BD - Withstands higher current and power

SMD transistors, see this code book: http://www.marsport.org.uk/smd/mainframe.htm

Resistors

SMT/SMD Resistors work on three digits or four digits. The last one is always the power to amount. One with a zero is just a connector (no resistance). Resistances less than 10 ohms have 'R' to indicate the position of the decimal point.
Like so:
1R2 is 1.2 ohms
330 is 33 x 1 =  33 ohms (not 330 ohms)
221 is 22 x 10 = 220 ohms
474 is 47 x 10000 = 470.000 ohms