Photodiode Operation and Characteristics: Photodiode Operation - When a pn-Junction is reverse biased, a small reverse saturation current flows due to thermally generated holes and electrons being swept across the junction as minority charge carriers.…
Photoconductive Cell Construction and Working: Photoconductive Cell Construction and Working - Light striking the surface of a material can provide sufficient energy to cause electrons within the material to break away from their atoms. Thus,…
LED Seven Segment Display: The arrangement of a LED Seven Segment Display is shown in Fig. 20-6(a). The actual LED devices are very small, so, to enlarge the lighted surface, solid plastic light pipes are…
Light Units: The total light energy output, or luminous flux (Φs), from a source can be measured in milliwatts (mW) or in lumens (1m), where 1 Im = 1.496 mW. The luminous intensity (Es) (also…
Programmable Unijunction Transistor: PUT Operation - The Programmable Unijunction Transistor (PUT) is actually an SCR-type device used to simulate a UJT. The interbase resistance (RBB) and the intrinsic standoff ratio (η) can be programmed to…
UJT Circuit Diagram: UJT Circuit Diagram Operation : The Unijunction transistor (UJT) consists of a bar of lightly-doped n-type silicon with a block of p-type material on one side, [see Fig. 19-39(a)].The end terminals of…
Silicon Bilateral Switch: It might be convenient to think of a Silicon Bilateral Switch (SBS) as an SUS with a gate terminal, or as a low-current TRIAC. However, the SBS is not simply another four-layer device.…
Silicon Unilateral Switch: The Silicon Unilateral Switch (SUS), also known as a four layer diode and as a Schokley diode, can be treated as a low-current SCR without a gate terminal. Figure 19-30 shows the…
TRIAC Control Circuit Diagram: A TRIAC Control Circuit Diagram that allows approximately 180° of phase control is shown in Fig. 19-27(a). The waveforms in Fig. 19-27(b) illustrate the circuit operation. With the TRIAC (Q1) off…
TRIAC Operation and Characteristics: The basic construction, equivalent circuit, graphic symbol and TRIAC Operation and Characteristics are shown in Fig. 19-21. The TRIAC behaves as two inverse-parallel connected SCRs with a single gate terminal. Sections…
