As the pot slider is moved, the voltage at the base of the transistor is changed, and this correspondingly alters the emitter voltage across the lamp, and the lamp intensity changes accordingly. Here, the pot resistance along with the 1 K resistor forms a resistive divider network at the base of the transistor. The 0.7 V difference is due to the minimum forward voltage drop rating of the transistor across the base emitter. For example, if the base voltage is 6 V, the emitter will 6 - 0.7 = 5.3 V and so on. To be precise the emitter voltage will be just 0.7 V behind the base voltage. We call it emitter-follower, because the voltage at the emitter or across the bulb follows the voltage at the base of the transistor. You can see as the variable resistor or the pot is varied, the lamp intensity also varies. The following configuration shows how a transistor can be used as a light dimmer using a emitter follower circuit. If you are confused about the relay, you can refer to this comprehensive article which explains everything about relay configurations. Here's the standard circuit for the same:
HOW TO USE 2N3055 TRANSISTOR HOW TO
I have already explained in one of my earlier posts regarding how to make a transistor driver circuit.īasically it uses the same configuration as shown above. R b = (Base Supply V b - Base-Emitter Forward Voltage) x hFE / Load CurrentĪlso remember that, the negative or the ground line of the external voltage must be connected with the transistor ground line or the emitter, otherwise the external voltage will have no effect on the transistor. The base resistor value can be calculated using the formula: You can see when a small external voltage is applied to the base, the transistor switches ON and conducts heavier current across the collector emitter terminals, switching on a bigger load. This is the standard method of using any transistor like a switch for controlling a given load. How to use Transistors like a Switchīipolar transistors are generally a three lead active electronic component which fundamentally work as a switch for either switching ON or switching OFF power to an external load or an associated electronic stage of the circuit.Ī classic example can be seen below, where a transistor is connected as a common emitter amplifier: Here we’ll study the functions and the way of handling and implementing bipolar transistors into practical circuits. New electronic hobbyists usually find it difficult to handle these useful components and configure them as circuits for an intended application. Even ICs are made up of 1000s of closely knit transistors which constitute the features of the particular chip. If there wouldn’t be transistors there wouldn’t be any ICs or any other semiconductor component. Transistors (BJTs) are the building blocks of all semiconductor devices found today. A low power signal across Gate/Source terminal allows the transistor to switch a comparatively high power load across its collector terminal.įor the sake of simplicity we will discuss BJTs here, since their charcaeritics is less complex compared to MOSFETs. A low power signal across base/emitter terminal allows the transistor to switch a comparatively high power load across its collector terminal.įor MOSFETs these are designated as Gate, Source, Drain. Transistors are basically of two types: bipolar junction transistor (BJT), and metal–oxide–semiconductor field-effect transistor ( MOSFET)įor a BJT, the 3 terminals are designated as base, emitter, collector. Transistors are 3 terminal semiconductor devices which is able to conduct relatively high power across their two terminals, in response to a significantly low power input at the third terminal.
0 kommentar(er)
