Obtaining electrical components can be difficult. Sometimes you are sorting through thousands of different components to find what you need and sometimes you can’t find what you are looking for. Most of the information in this section is directed at people working with circuits below the 10 Mhz range. I like to breadboard my prototypes and the inductive/capacitive characteristics of the board can become much more noticable at higher frequencies.
Radio Shack sells a 500 resistor pack with a variety of values. This is not expensive and gives you most of what you will need.
The image below if of PV36 series trimmer. I absoluely love these because I can tune it to whatever value I want with a precision screwdriver and they fit nicely into the breadboard. They come in values ranging from 10 ohms to 2 Mohms.
In the range below 0.1 μF the most versatile is the Ceramic capacitor. They are cheap, reliable, high voltage, and can handle high frequencies well.
For the range of 100μF to 0.1μF tantalium electrolitic caps are great because of their compact size. They don’t do well with RF and are not very accurate.
The really big caps are the Aluminum electrolytic. These are great because of their high capcitance values but they contain chemical agents that can cause leaks and explosions
These components come in all shapes, sizes, and forms. For inductors with fixed values the conformal choke looks like a resistor and is easy to work with.
Variable inductors are hard to find but I got this one from a distributor named Coilcraft. This one contains an ferrite slug that is turned with a special tool that you can also buy from the store.
Ferrite cores are magnetically reactive materials with different properties, sizes, and shapes. It is useful to have some ferrite toroids avaiable in the event that you need an inductor with a value that you did not buy. You can wrap magnet wire around the toroid to produce any inductance you need.
The image below is a homemade transformer of mine. You can easily calculate the inductance if you know the permeability of the core and the number of turns of the wire. In the future I may add a section on constructing inductors and transformers from ferrite materials.
CWS Bytemark is a good distributor of these non-saturable cores. The saturable cores are much harder to find but not impossible.
(let me know if this information is useful and I will add more)
Radio Shack: They are a first place to look for basic components.
Digikey: They have tens of thousands of different components available but they are more geared to industry and it can be difficult to hunt down what you are looking for.
Newark: The selection offered by them is very good. They are better then Digikey for smaller quantities of less common parts.
Mouser: No minimum and a pretty good selection. (thanks Elliott)