Miscellaneous Circuits
We saw in our last tutorial that a permanent magnet moving-coil (PMMC) galvanometer is a type of instrument in which a current carrying coil is placed within a permanent magnetic field. When an electric current ( I ) passes through the coil, the electromagnetic field created around it reacts against the permanent…
When analysing the operation of electrical and electronic circuits, or trying to understand why a circuit does not work as expected, eventually you will need to use a Voltmeter to measure the various voltage levels. Voltmeters used for the measurement of voltage come in many shapes and sizes, either analogue or digital,…
Nearly all electronic devices and circuits require some form of a DC power source for their operation either from a battery, solar cell or as a mains power supply. While batteries have the advantage of being small, portable and ripple free, they need replacing (or recharging) frequently and are also…
The advantage of relays is that it takes a relatively small amount of power to operate the relay coil, but the relay itself can be used to control motors, heaters, lamps or AC circuits which themselves can draw a lot more electrical power. The electro-mechanical relay is an output device…
The emission of these photons occurs when the diode junction is forward biased by an external voltage allowing current to flow across its junction, and in Electronics we call this process electroluminescence. The actual colour of the visible light emitted by an LED, ranging from blue to red to orange,…
There are many circuits and kits on the market that can flash any number of lights periodically, randomly or sequentially but one very versatile IC that the hobbyist or student can use to produce a simple Christmas Lights Sequencer for use in a variety of different seasonal lighting displays is the CMOS 4017B…
The Wheatstone Bridge diamond shaped circuit who’s concept was developed by Charles Wheatstone can be used to accurately measure unknown resistance values, or as a means of calibrating measuring instruments, voltmeters, ammeters, etc, by the use of a variable resistance and a simple mathematical formula. Although today digital multimeters provide the simplest…
The I-V Characteristic Curves, which is short for Current-Voltage Characteristic Curves or simply I-V curves of an electrical device or component, are a set of graphical curves which are used to define its operation within an electrical circuit. As its name suggests, I-V characteristic curves show the relationship between the current flowing through an electronic…
We know from our tutorials about Transformers that they can not only provide a step-down (or step-up) voltage, but they also provide “electrical isolation” between the higher voltage on the primary side and the lower voltage on the secondary side. In other words, transformers isolate the primary input voltage from…
Continuing on from our tutorial about converting an ATX PSU to a bench power supply, one very good addition to this is the LM317T positive voltage regulator. The LM317T is an adjustable 3-terminal positive voltage regulator capable of supplying different DC voltage outputs other than the fixed voltage power supply…
In the tutorial about Rectifiers, we saw that the DC output voltage being controlled by the rectifier is at a value below that of the mains input voltage. The Voltage Multiplier, however, is a special type of diode rectifier circuit which can potentially produce an output voltage many times greater than of…
But before we start looking at the in’s and out’s of pulse width modulation we need to understand a little more about how a DC motor works. Next to stepper motors, the Permanent Magnet DC Motor (PMDC) is the most commonly used type of small direct current motor available producing…