Musical Instruments used in Carnatic music and bhajans

There are several instruments used as follows including others.

Stuthi
Veena
Mrindamgam
Kenchara
Ghatam
flute
Violin
Kinnaram

I give herein a brief of stuthi/Veena:

The harmonium is also known as peti or baja. This instrument is not a native Indian instrument. It is a European instrument which was imported in the 19th century. It is a reed organ with hand pumped bellows. Although it is a relatively recent introduction, it has spread throughout the subcontinent. Today, it is used in virtually every musical genre including South Indian Bhajans. This is also used in place of stuthi box.

The surpeti, also called swar pethi, swar peti, swarpeti, surpeti, sur peti, sruti box, or shruti box, is an Indian drone instrument. It is a small box whose only function is to provide the drone. There are two, basic forms, one is manual and the other is electronic.
Saraswati vina (Saraswathi veena) is the instrument associated with Saraswati, the goddess of learning and the arts. This instrument is common in south India and is an important instrument in carnatic sangeet. It is variously called simply vina, or veena, the "Saraswati" part being implied.

The saraswati vina has an interesting construction. It has a body made of wood, generally, this is jackwood. The highest quality vinas have the entire body carved from a single block of wood, while the ordinary vinas have a body which is carved in three sections (resonator, neck and head). There are 24 frets made of brass bars set into wax. (see "Fretting and Fingering the Vina") There is another resonator at the top of the neck. This is no longer a functioning resonator, but is mainly used as a stand to facilitate the positioning of the instrument when it is played. Because it is no longer functioning it is not unusual to find that this upper resonator may be made of acoustically neutral materials such as paper mache, cane or other similar materials. Unlike north Indian instruments like the sitar, the saraswati vina has no sympathetic strings. It has only four playing strings and three drone strings (thalam). (see also "Tuning the Vina") The main bridge is a flat bar made of brass. This bar has a very slight curve. It is this light curve which gives the vina its characteristic sound. A major centre for the manufacture of the saraswati vini is in Tanjore.