If you've been reading all the other chord construction entries this should make perfect sense. If you haven't then can I suggest you back track and read those first. I'll make a lot more sense if you do.

Suspended chords
The two suspended chords that I'm going to discuss here. sus2 and sus4.

Sus2
A sus2 chord has a scale spelling of 1, 2, 5. Yep that's right, no third. This means it's neither a major or a minor chord. So, as usual using C.

1 = C
2 = D
5 = G

Sus4
You can probably now work out that a sus4 chord has a scale spelling of 1,4, 5.
Again in C this gives you.

1 = C
4 = F
5 = G

Really good example of the use of a sus4 chord is the intro to Crazy Little Thing Called Love by Queen.

5th Chords
A very simple chord this one. It's scale spelling is 1, 5, 8 so all you're getting is the root note, the fifth and the octave. Once again in C

1 = C
5 = G
8 = C

A lot of people don't actually play the octave which is theoretically incorrect (as a chord is three or more notes) but as this particular chord is fairly neutral in sound and sonically has very few overtones it sounds great when used with an overdriven or distorted sound. That's why this chord is loved by rock guitarists the world over.

It's been a very long time since my last post, but I said I'd be looking at diminished chords. 

Diminished Chords
A bog standard plain diminished chord, is in reality nothing more than a standard minor chord triad (which as I've stated before has a scale spelling of 1, b3, 5) and flattening the 5th note as well. So going back to C you'd get.

1 = C
b3 = Eb
b5 = Gb

So this would be called a C diminished chord.

Half-Diminished or m7b5 chords
So how do we make it a half-diminished chord. Well bizarrely a half-diminished chord is really a minor 7th chord (remember the scale spelling for that 1, b3, 5, b7) but with the 5th flattened also, so you get 1, b3, b5, b7. So again in  C.

1 = C
b3 = Eb
b5 = Gb
b7 = Bb

So if you think about this as it's a minor 7th chord with a flattened 5th, it's become more popularly known as a minor 7 flat 5 (m7b5) chord and certainly in popular music you'll find more people who know it by that name, rather than half-diminished.

Diminished 7th chords
So how do  you make a full diminished 7th chord.

Pretty easily actually. All you need to do is take a half-diminished (m7b5) chord and flatten the 7th note AGAIN. Yes that's right again. So the scale spelling of a diminished 7th chord is 1, b3, b5, bb7. 

So again in C you get these notes.

1 = C
b3 = Eb
b5 = Gb
b7 = Bbb (yes music theory caters for double flats so whilst it's actually the same note that we'd generally call A it's called Bbb).