LM317T Voltage Regulator with Pass Transistor

Circuits for Analog System Design by Prof. MK Gunasekaran ,Department of Electronics Design and Technology, IISC Bangalore. For more details on NPTEL visit nptel.iitm.ac.in



http://www.youtube.com/watch?v=nOOOAjoqCt8&hl=en

This video shows a DC to AC power inverter that has a regulatet output voltage, and there is no intergrated circuit used. The 50Hz square wave signal gets generated by a 2 transistor oscillator. The 50hz square wave signal then gets amplified with driver transistors, which "drive" the fullbridge that consists 2 TIP122 and 2 TIP127 darlington transistors. So this fullbridge switches the transformer to the power supply and changes it´s polarity - that results AC and this AC is beeing amplified by the transformer. The voltage regulation system consists mainly a voltage divider and a transistor that is "pre biased" and then gets negative voltage from the voltage divider. The NPN transistor then amplifies the difference from these voltages and leads it to the TIP127 PNP transistor which is mainly reliable for the power that gets fed into the transformer. This power inverter does not have that good efficiency. The transistors get pretty hot after some minutes of running the CD radio that I showed. Also the input voltage must be at least 6V higher than the transformer voltage...With a 18V transformer, and 24V input to the power inverter I was able to power a 230V 40W bulb at it´s normal brightness, but the bulb was "flickering" so I don´t know if that came from the power supply or the inverter. This project is rather some kind of "proof of concept" project that I made, but I will share the circuit diagramm soon so you can re built the inverter if you want. The frequency is ...



http://www.youtube.com/watch?v=D2fBIPZomuc&hl=en

This is a car ignition coil driven modified CFL light. The circuit is only two very small transistors. The circuit self oscillates by feeding back a pulse signal gathered by a thin wire that is wrapped around the base of the ignition coil. A step down adjustable voltage regulator is used to control the power coming out of a small AA battery pack. A wave form is shown on a oscilloscope. The device is running on 4.5 volts (regulated) at 20 milliamps.



http://www.youtube.com/watch?v=2ySO2NXh3jw&hl=en

A video by Tom Lieurance for renewable energy technology students at Columbia Gorge Community College.



http://www.youtube.com/watch?v=ywkMv5_XSk0&hl=en