Making Syllables - Consonants with Consonants

Below are the forms the consonants take when they appear in samyuktaakShara-s (syllables), along with another consonant -

क्‍  ख्‍  ग्‍  घ्‍  ङ्‍
च्‍  छ्‍  ज्‍  झ्‍  ञ्‍
ट्‍  ठ्‍  ड्‍  ढ्‍  ण्‍
त्‍  थ्‍  द्‍  ध्‍  न्‍
प्‍  फ्‍  ब्‍  भ्‍  म्‍

य्‍  र्‍  ल्‍  व्‍
श्‍  ष्‍  स्‍
ह्‍

र is a special case.  The rule to write र् in a samyuktaakShara are -
If a र् comes before another consonant, then it is represented as 'a half sickle on top of the following consonant'.  Ex. र्क, as in तर्क (logic)
If a full र comes after any other half consonant, it takes the form of 'a slash under the consonant preceding it'.  Ex. क्र तक्र (curd).

Some special combinations that come often in the language are given special syllable notations too.  They are 
क् + ष = क्ष 
त् + र = त्र
ज् + ञ = ज्ञ