RESISTORS
Surface Mount resistors are manufactured in many standard sizes. Our trainer kits use the common sizes that teach the beginner to handle them comfortably. The size code describes the dimensions of the resistor. A 1206 resistor is 0.12 inch long and 0.06 inch wide.

Surface Mount resistors are marked with a three digit code for ± 5% tolerance devices and a four digit code for ± 1% or ± 2% devices. In the case of three digit codes the first two digits specify the first two digits of the resistance and the third digit is a multiplier (number of zeroes). In the case of four digit codes the first three digits specify the first three digits of the resistance and the fourth digit is a multiplier (number of zeroes). The figure arrived at is the resistance in Ohms. Resistors of less than 10W are marked with an R in place of the decimal point e.g. 6.8W is marked 6R8.

A commonly used devices in Surface Mount circuits is the 0W jumper which is identical, in shape and size, to the usual Surface Mount resistor. This device is marked 000 and has no resistance. It is used to bridge one track over another on the PCB.

CAPACITORS
Multilayer ceramic chip capacitors are used in most applications. They come in similar sizes as chip resistors and the the common sizes have been selected again in our trainer kits for reasons already explained. They are usually unmarked so special care must be taken while handling . The standard values are from 0.47pF to 2.2mF in a range of 16 to 50 volts.

Tantalum chip capacitors are produced in a range of values and voltages. A typical tantalum with a capacitance of 10m F and voltage 16 measures about 5.8mm by 4.5mm. It is enclosed in a plastic package with terminals at each end. The package is directly marked with the capacitance and voltage; polarity is indicated by a band at the positive end.

INDUCTORS
SMT has many important applications in the field of radio communication that has led to the availability of a wide variety of inductors. Their package construction is similar to that of the tantalum chip capacitors.

SEMICONDUCTORS
The most popular package used for transistors, diodes, zeners, and LEDs is the SOT23. The pinout for transistors is generally standard for all manufacturers with very rare exceptions. Pinouts for diodes vary, as many packages contain two diodes, connected either in common-anode or common-cathode mode or as two separate diodes. With a single diode, terminal 2 is usually the anode and terminal 3 is the cathode, with no connection to terminal 1.

PRESETS
Variable cermet resistors are available in the usual range of values. Their size is about 3 to 4mm square.

INTEGRATED CIRCUITS
Operational amplifiers, comparators, audio amplifiers, timers, CMOS logic, 74HC logic, RAMs, optocouplers, voltage references, voltage regulators, etc., are available in SMD form. All these ICs are usually given their original type numbers with a suffix, most often ‘D’, to indicate that they are SMD. Packages are termed SO (small outline) followed by an indication of the number of pins. SO14 is a 14-pin IC. SMD ICs have the same specifications and pin-outs as their through-hole versions. Pin number ‘1’ is indicated either by a dot or bar. Another indicator is the bevelled top edge of the package along the pin number ‘1’ side.