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Hardware and systems issues
Published in Francis Rumsey, Desktop Audio Technology, 2003
The interface incorporates an opto-isolator between the MIDI IN (that is the receiving socket) and the device’s microprocessor system. This is to ensure that there is no direct electrical link between devices and helps to reduce the effects of any problems that might occur if one instrument in a system were to develop an electrical fault. An opto-isolator is an encapsulated device in which a light-emitting diode (LED) can be turned on or off depending on the voltage applied across its terminals, illuminating a photo-transistor which consequently conducts or not, depending on the state of the LED. Thus the data is transferred optically, rather than electrically. In the MIDI specification, the opto-isolator is defined as having a rise time of no more than 2 μs. The rise time affects the speed with which the device reacts to a change in its input and if slow will tend to distort the leading edge of data bit cells, as shown in Figure 5.23. The same also applies in practice to fall times.
Real-World Control Device Interfacing
Published in A. Arockia Bazil Raj, FPGA-Based Embedded System Developer's Guide, 2018
In general, electrical signals are transmitted from one point to another using various components and media. For example, in the television remote control, the IR-Tx transmits the electrical signal from the remote circuit to the TV internal circuit, that is, IR-Rx. In the same way, RF, LED, acoustic signals, phonons, and lasers can also be used to transfer electrical signals. In this section, we discuss the working principles and applications of the opto-isolator circuit. As we know, transformers provide a step-down voltage as well as 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 the secondary output voltage using electromagnetic coupling by means of a magnetic flux circulating within the iron-laminated core. We can also provide electrical isolation between an input source and an output load using just light by using an opto-isolator. An opto-isolator is also known as an optical isolator, photocoupler, or opto-coupler. It is one of the electrical/electronic components used for transferring electrical signals from one circuit to another with isolation using light [114]. In general, a combination of LEDs and phototransistors are used in a typical opto-isolator IC packed in a single opaque package, as shown in Figure 9.5a. The basic design of an opto-coupler consists of an LED that produces infra-red light and a semiconductor photosensitive device that is used to detect the emitted infrared beam. Both the LED and photosensitive device are enclosed in a light-tight body or package with metal legs for the external wiring.
Diodes and power supplies
Published in David Crecraft, David Gorham, electronics, 2018
One of the reasons for using a mains transformer in a linear power supply is to achieve isolation between the mains and the circuit that is being powered, for safety. Such isolation can be achieved in the circuit of Fig. 8.16 by introducing an opto-isolator into the feedback path between the output and input. The opto-isolator is a small plastic package containing a light emitting diode (which emits light when a forward current is passed) close to a photodiode (through which a large reverse current can flow depending upon the amount of light falling on it). Hence a signal can be passed from the output to the switch of this device with no electrical connection between them, but using light as the pathway.
Feedback Controller Design for a Boost Converter Through a Colony of Foraging Ants
Published in Electric Power Components and Systems, 2012
As the output of the comparator is not sufficient for amplification and isolation, the pulses from the comparator are given to the gate driving circuit, which is shown in Figure 3. The Opto coupler MCT2E (Texas Instruments, Dallas, Texas, USA) is used for isolation, and the two switching transistors T1 and T2 are used for voltage amplification. When the modulator output voltage goes high, it drives the switching transistor 2N2222 into conduction. The collector current of this transistor drives the LED in the opto-isolator, which turns ON transistor T1 in the isolator. This process grounds the base terminal of T2, and therefore, T2 remains OFF. Its collector voltage—which is the fate to source voltage—swings to +15 V now, turning ON the MOSFET. Thus, the gate driver circuit provides electrical isolation together with voltage amplification.
Hardware design implementation issues of the estimator-based controller using FPGA
Published in International Journal of Electronics, 2019
Kanthimathi R., Kamala J., Jaibalaganesh T., Vasuhi S.
Hardware implementation of the controller is realised with Atlys Spartan-6 XC6SLX45 FPGA (Xilinx Spartan®-6 LX45 FPGA, www.digilentinc.com). Hardware set-up is shown in Figure 14. ADC0809 with a conversion time of 100 μs is used to convert analogue output voltage into 8-bit digital data. Signals of ADC are converted into 3.3 V using 74LVX245 trans-receiver and connected to Spartan FPGA. These 8-bit data are converted into 16-bit data for state estimation purpose. The error signal is generated by comparing estimated voltage with the reference voltage. Based on the error, control signal (PWM signal) applied to the converter is varied. PWM signal is applied to switching transistor through driver and isolator circuit. Opto-isolator TLP250 is used for isolation.
A Real-Time Application of Modified Inductor Coupled KY Converter Topology in Speed Control of E-Bikes
Published in Electric Power Components and Systems, 2019
Varun Krishnan K. S., Preethi Thekkath
The driver circuit consist of Opto-Isolator IC and Driver IC. Opto-Isolator provides an optical isolation between the low voltage control side and the high voltage power circuit side. Driver IC provides an adequate lift in the voltage level of PWM signal (PWM amplitude = 5 V), sufficient to turn on the MOSFETs (VGS = 10 to 20 V).