Not Understanding Circuit ,Help!

[NishantSood]

I want know what the different components do in this circuit and why they are there:

**broken link removed**

 

[plingane]

Here is a hint. The resistor at the left is a thermistor whose resistance changes as a function of temperature. Thus this circuit is an audio oscillator whose output frequency varies with temperature. The potentiometer across the thermistor sets the oscillation frequency at a specific temperature.

 

[NishantSood]

By potentiometer you mean the trim pot

 

[MQuadros]

Yup, trim pot is the same as trimmer potentiometer. The NPN PNP pair of transistors are acting as a simple audio amplifier for this circuit, where the base current for T1 is varied depending on the thermistor and potentiometer.