What is an electrical control circuit

Understand physics 4, textbook

70 3  Workbook, pages 36–37 The transistor - a switching amplifier 1. How are transistors constructed? In contrast to other components, transistors have not just two, but three connections (Fig.70.1 and 70.2). These are called emitter E (for lat. Emittere ... to send out), collector C (for lat. Colligere ... collect) and base B. 2. How do transistors work in a circuit? The physicists Shockley, Bardeen and Brattain worked on the Lilienfeld patents ( page 41). They discovered that a certain layer sequence of p- and n-conductors can produce a switch and amplifier effect. Weak steers strong! (Fig.70.3) E1 Recreate the adjacent circuit. Pay attention to the correct connection of E, C and B! How does the 1.5 V cell have to be connected to control circuit B / E so that the lamp lights up? If you let a weak electric current flow through the base and emitter, the collector-emitter path becomes conductive. We call the base-emitter circuit "control circuit" because we use it to control a circuit (like a switch). We call the circuit that runs through the collector “working circuit” (Fig.70.4). 3. How can transistors act as amplifiers? Controlled with light! (Fig.70.5) E1 Recreate the adjacent circuit. Working group: collector - lamp - positive pole, emitter - negative pole Control circuit: base - 1-k Ω -LDR - positive pole The lamp brightness can be regulated by darkening and illuminating the LDR. E E E B B B C C C 70.1 Types of transistors pnp transistor npn transistor Collector (C) Base (B) Emitter (E) C B E C B E C B + + + - - - E 70.2 This is how transistors are constructed. A transistor consists of three semiconductor layers in the order p-n-p or n-p-n. The two outer layers are called emitter E and collector C, the middle layer is called base B. M V1 BC 549 6V / 0.3W 1 kΩ 1.5V = 9V = C E B 70.3 weak controls strong! If a weak electrical current flows in the control circuit (B / E), a strong current can be controlled in the working circuit (E / C). M control current electron current working current n n p 70.4 A small control current opens the way for a stronger working current. V2 BC 549 9V = 6V / 0.3W C E B LDR 1 k Ω 70.5 Controlled by light! 70.6 Transistors in a radio, for example, amplify sound signals. For testing purposes only - property of the publisher öbv