let's try that again, in English.
If yuou'll notice, there's only one note different between a V7 chord and a diminished 7th chord a half step above it, in a given key- in e, for example, a B7 contains B, D#, F, and Ab, while a Cdim7 contains the same last three pitches, but with a C instead of a B. Suggestion? Sub a Cdim7 for a B7. Enharmonically, it's a B7b9, but a diminished is a diminished. and, any inversion of a diminished chord (a diminished chord in it;s own right, as every note in a dim chord is the same intgerval apart- you can slide a dim grip up and down the neck without changing a thing, and be playing iversions) can be subbed in for this- Cdim7, D#dim7, Fdim7, and Abdim7 are all good substitutions for a Bdim7.
Also, a half-step below a major or harmonic minor key's root, you'll find a diminished chord. Speaking on a strictly technical level, you'll find that this is simply a substitution for a V chord, inverted- in the above example, i's the D#- but if you harmonize the scale, tht;s what you build over the 7th degree,and depending on how you harmonize it, you can suggest this harmonically, rather than the V.
Taking another step back, anywhere you can play a M7 chord, you can play a dim7 a half step above. For example, take a secondary dominant- in the jazz world, in a minor blues, it's not uncommon to go from a minor i, briefly into a minor iv, and then back to the i, like you would in a SRV-ish swing blues, before going to the iv. But, before hitting the iv, you'd quickly hit a I7, or a "secondary dominant"- a chord functioning as the dominant chord of a chord that isn;t the primary key center- this is a common way of going
utside" while still sounding consonant. So, instead of going Am-Dm-Am-A7- and into Dm, you could go Am-Dm-Am-Bbdim7.
This is just scratching the surface, of course... just play them a lot and wait till they sound natural.
-D
