Unlike electro-mechanical relays (EMR) which use coils, magnetic fields, springs and mechanical contacts to operate and switch a supply, the solid state relay, or SSR, has no moving parts but instead uses the electrical and optical properties of solid state semiconductors to perform its input to output isolation and switching…
We would like to think that the AC or DC power supplies we use to power our circuits are both clean and well-regulated supplies. However, the switching of AC inductive loads or the switching of DC relay contacts and DC motors as part of a micro-controller project all combine to…
We saw in the previous tutorial that the process of converting an AC input supply into a fixed DC supply is called Rectification with the most popular circuits used to perform this rectification process is one that is based on solid-state semiconductor diodes. In fact, rectification of alternating voltages is one of…
Rectification converts an oscillating sinusoidal AC voltage source into a constant current DC voltage supply by means of diodes, thyristors, transistors, or converters. This rectifying process can take on many forms with half-wave, full-wave, uncontrolled and fully-controlled rectifiers transforming a single-phase or three-phase supply into a constant DC level. In…
Linear voltage regulators are generally much more efficient and easier to use than equivalent voltage regulator circuits made from discrete components such a zener diode and a resistor, or transistors and even op-amps. The most popular linear and fixed output voltage regulator types are by far the 78… positive output…
The Unijunction Transistor or UJT for short, is another solid state three terminal device that can be used in gate pulse, timing circuits and trigger generator applications to switch and control either thyristors and triac’s for AC power control type applications. Like diodes, unijunction transistors are constructed from separate P-type and N-type semiconductor materials…
The Insulated Gate Bipolar Transistor also called an IGBT for short, is something of a cross between a conventional Bipolar Junction Transistor, (BJT) and a Field Effect Transistor, (MOSFET) making it ideal as a semiconductor switching device. The IGBT Transistor takes the best parts of these two types of common transistors, the high input impedance and high switching…
The DIode AC switch, or Diac for short, is another solid state, three-layer, two-junction semiconductor device but unlike the transistor the Diac has no base connection making it a two terminal device, labelled A1 and A2. Diac’s are an electronic component which offer no control or amplification but act much like a bidirectional switching diode as they can…
Being a solid state device, thyristors can be used to control lamps, motors, or heaters etc. However, one of the problems of using a thyristor for controlling such circuits is that like a diode, the “thyristor” is a unidirectional device, meaning that it passes current in one direction only, from Anode to Cathode….
In the previous tutorial we looked at the basic construction and operation of the Silicon Controlled Rectifier more commonly known as a Thyristor. This time we will look at how we can use the thyristor and thyristor switching circuits to control much larger loads such as lamps, motors, or heaters…
It is a multi-layer semiconductor device, hence the “silicon” part of its name. It requires a gate signal to turn it “ON”, the “controlled” part of the name and once “ON” it behaves like a rectifying diode, the “rectifier” part of the name. In fact the circuit symbol for the thyristor suggests…