Standard Component Values
From: http://eeshop.unl.edu/standard_values.html
While passive electronic components like capacitors, inductors, and resistors 
can be manufactured to have almost any value, in practice most are produced in 
standard values.

Standard values are multiples of: 
10, 15, 18, 22, 27, 33, 47, 51, 68, 75, 82, and 91.

So, for example, you can easily get a .47 uFd capacitor or a 220 ohm resistor.
You will not likely find a .53 uFd capacitor or a .17 mH inductor.

Resistors DO come in a greater variety of precision values, and can be easily
combined (or replaced with inexpensive potentiometers) to obtain arbitrary 
values. So it's almost always better, when calculating component values for a
circuit, to make the capacitor or inductor values standard, and then make the
resistors be the "variable" item.

PRECISION: It is also important to understand how precise passive components
values actually are. Standard resistors are only accurate to 5% or 10%; but
where it's critical, some can be had in 1% or better accuracy. But capacitors
(especially large electrolytics) are only guaranteed to be within 20% of their
specified value. Likewise common inductors are typically only 10% precision.

The importance of precision depends on the application. A designer will probably
use a common 220 ohm resistor to limit current in an LED panel indicator because
a little difference in brightness either way is not important. In setting the
gain of an instrumentation amplifier, or the pulse width in a timing circuit,
the selection of precise component values may be more critical.
Here are the component values the EE Shop presently attempts to keep available.



CERAMIC CAPACITORS:
(in pFd) 10, 22, 33, 47, 68, 100, 150, 220, 330, 470, 560 ; (in uFd) .001, 
.0022, .0033, .0047 uFd; .0068, .01, .022, .033, .047, .1, 1



FILM CAPACITORS:
(all in uFd) .001, .0015, .0047, .01, .022, .03, .047, .068, .1, .22, .33, .47



ELECTROLYTIC CAPACITORS:
1, 2.2, 3.3, 4.7, 10, 22, 47, 100, 220, 470, 1000, 8200, 10000 uFd



TANTALUM CAPACITORS:
.1, .33, .47, 1, 2.2, 3.3, 4.7, 10, 22 uFd



RESISTORS:
Most standard values available in 1/4 watt size. Precision "in-between" values
also available. Uneven assortment of power resistors (i.e., higher than 1/2 
watt) Note in the list above that we sell a boxed 365 piece kit containing 5
each of 73 standard value resistors for only $7.50.



INDUCTORS:
The Shop has fewer inductors than any other kind of component because they are
relatively expensive, vary widely in price/size depending upon application, and 
are often avoided in modern designs for a variety of technical reasons. Most of
what we have are low-current axial leaded chokes, in these values: (microhenries):
.1, .15, .47, .68, 1, 1.5, 2.2, 3.3, 4.7, 6.8, 8.2, 10, 15, 22, 33, 47, 68, 100,
120, 150, 220, 330, 470, 680, 1000 (millihenries) 10, 22, 33, 47, 68, 100.

Thoughts
I have always enjoyed building electronic devices (and computers) so 
when I needed a sensor for the dust accumulation in my 6" dust collector
and discovered Raspberry pi and Arduino it really started me thinking.
I had recently built a BCD clock with descrete components, but started
rethinking this and other possibilities.  I showed Betty a video of a propeller 
clock and she wanted one, so...

Lately I have been using a lot of Arduinos for real-time control, like the 
Dust Bin Sensor, Arduino Data Terminal, Sliding dust valve,
Dust Collection Automation, and Environmental Sensor. 
  
I usualy use an Uno (to develop code) since I can easily replace the chip when
flash quits working, and Nano for the end product.

I am having a problem with IR remotes not controlling HDMI switches, so...

Please take a look at my IRremote page.

Miniature Volt Ammeter diagram. Skiz