TRANSISTOR

can we amplify the voltage to hundreds of volt by using transistor from the 9v or any small voltage source and therefore can use it for running televisions and other devices?

Televisions don't need to use high voltages any more ;)

Yes, DC-DC conversion is used in many things, good example is a camera flash - the flash discharge tube needs a few hundred volts and the usual technique is a power oscillator driving a step-up transformer, and the transformer secondary is rectified to charge a capacitor. Have a google around for camera flash driver circuits - there will be lots of examples I suspect.

For lower voltages DC-DC conversion often uses a boost or buck or boost-buck switch-mode circuit - avoiding needing a transformer, but requiring a inductor.

And any convenient switching device can be used for driving these circuits, either bipolar or MOSFET. (In the very old days the oscillator might be electromechanical even!).

A4kash: can we amplify the voltage to hundreds of volt by using transistor from the 9v or any small voltage source and therefore can use it for running televisions and other devices?

Amps multiplied by volts is a constant.

If you multiply the volts by 100 you'll get 100 times less amps - not enough for a TV.

fungus:

A4kash: can we amplify the voltage to hundreds of volt by using transistor from the 9v or any small voltage source and therefore can use it for running televisions and other devices?

Amps multiplied by volts is a constant.

If you multiply the volts by 100 you'll get 100 times less amps - not enough for a TV.

does it mean that if we are gaining the certain amount of volatge from transistor then we are also decreasing the current from transisitor by ceratin amount?

A4kash: does it mean that if we are gaining the certain amount of volatge from transistor then we are also decreasing the current from transisitor by ceratin amount?

Yes.