In this “on” state, current flows between the collector and emitter of the transistor. That is, when there is a positive potential difference measured from the emitter of an NPN transistor to its base (i.e., when the base is high relative to the emitter) as well as positive potential difference measured from the base to the collector, the transistor becomes active.

A small current entering the base is amplified to produce a large collector and emitter current. NPN is one of the two types of bipolar transistors, consisting of a layer of P-doped semiconductor (the “base”) between two N-doped layers. A classic analog alarm clock has an extra hand or inset dial that is used to specify the time at which to activate the alarm. To stop the sound or light, a button or handle on the clock is pressed but most clocks automatically stop the alarm if left unattended long enough. Some use sound, some use light, and some use sensors to identify when a person is in a light stage of sleep, in order to avoid waking someone when they’re deeply asleep, which causes tiredness, even if the person has had adequate sleep. The primary use of these clocks is to awaken people from their night’s sleep or short naps they are sometimes used for other reminders as well. Transformers are essential for the transmission, distribution, and utilization of electrical energy.Īn alarm clock is a clock that is designed to wake a person at a specific time. A wide range of transformer designs are used in electronic and electric power applications. Transformers range in size from thumbnail-sized used in microphones to units weighing hundreds of tons interconnecting the power grid. This varying magnetic flux induces a varying electromotive force (emf) or voltage in the secondary winding. A varying current in the primary winding creates a varying magnetic flux in the transformer’s core and thus a varying magnetic flux through the secondary winding. Material required: Transformer, NPN transistor, connecting wire, alarm watch, 12v battery.Ī transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. Aim : To make an alarm battery which will awake you at the correct given time.

Shock alarm clock uniland