Wednesday, 8 October 2014

Make a constant current source using transistors And Making of current mirror circuits,


Make a constant current source using transistors

         And

Making of current mirror circuits,
Introduction- you may be thinking, why I have to know making constant current source, and current mirror, answer is that actually what happens in many cases of powering a project we need a constant current source, so this project is very useful,

Components required- some matched n-p-n transistor, one reference resistance, and a primary voltage source,

Working principle of constant current, current mirror circuit in simple points-

1. take two matched transistor T 1 and T 2

2. connect together all of their emitter and base

3. so all have same base-emitter voltage.

4. so simply they produce same collector current

Circuit diagram-





 So in our upcoming project i show you the application of constant current source in circuit,


 Visit again, and don’t forget to leave a comment

what is transistor biasing?


               What is biasing?
The word biasing means applying voltage for required operation,
Transistor biasing- transistor biasing means deriving proper voltages (from a single voltage source), which are applied at input and output of the transistor, For active region operation, we must make the base-emitter junction forward biased and collector-base junction reverse biased



Tuesday, 7 October 2014

light dependent switching system, / automatic street light,/light controlled automatic switch on/off system,



Thank you reader for coming again,

Today’s project –light dependent switching system, / automatic street light,/light controlled automatic switch on/off system,

Basic idea  -     a light which gets on at night time and gets off at day time, depending on sunlight.

Theory-here a transistor acts as a switch, varying bias current using LDR and variable resistor, we make the transistor switch on and switched off mode,

Components required- any n-p-n transistor, a LDR, some resistances, one LED,

Circuit diagram-see the diagram given bellow


Controlling light sensitivity- by varying the resistance of the variable resistor, we can control the light sensitivity,
 The circuit I made- see the picture bellow