LED driving and controlling methods. I decided to write this quick tutorial for two reasons: First because there are many people who would like to know more about driving and controlling LED lights, and second because i was provided an excellent LED driver chip from Farnell for test, and i wanted to put it under the microscope.
So i will place this chip against some other LED drivers to see how good it is. The chip that I'm talking about is the A6210 from Allegro Microsystems. Basics: Open Collector Outputs. One of the joys of working with basic digital electronics– and logic gate ICs in particular –is that it almost works like building with a set of Lego blocks: One output goes here, which connects to the next input here, and so forth until it does what you wanted.
If you’ve played with chips like these, you’ve probably also come across chips with “open collector” outputs. And if not, they’re worth knowing about. Open-collector outputs form the basis of a number of clever tricks for level-shifting and interfacing between different types of logic, and from logic to other types of electronic circuits. In what follows, we’ll work with the SN7407N, which is one of the most basic ICs with open-collector outputs. We’ll discuss what it means to have “open collector” outputs, and show some of the different ways that they are used. This is a schematic symbol for the SN7407N, showing the pinout.
Intro to Phase-Locked Loops. Basics: Power dissipation and electronic components. An ever-present challenge in electronic circuit design is selecting suitable components that not only perform their intended task but also will survive under foreseeable operating conditions.
A big part of that process is making sure that your components will stay within their safe operating limits in terms of current, voltage, and power. Of those three, the “power” portion is often the most difficult (for both newcomers and experts) because the safe operating area can depend so strongly on the particulars of the situation. In what follows, we’ll introduce some of the basic concepts of power dissipation in electronic components, with an eye towards understanding how to select components for simple circuits with power limitations in mind.
Basics: Introduction to Zener Diodes. Zener diodes are a special type of semiconductor diode– devices that allow current to flow in one direction only –that also allow current to flow in the opposite direction, but only when exposed to enough voltage.
And while that sounds a bit esoteric, they’re actually among the handiest components ever to cross an engineer’s bench, providing great solutions to a number of common needs in circuit design. In what follows, we’ll show you how (and when) to use a Zener, for applications including simple reference voltages, clamping signals to specific voltage ranges, and easing the load on a voltage regulator. Background: Semiconductor diodes, real and ideal To understand how Zener diodes are different from other diodes, let’s first review the properties of regular diodes. Power Protection Circuits [419] Written by Jon Chandler Published on 18 December 2011 Hits: 16366 Multithumb found errors on this page: There was a problem loading image ' There was a problem loading image ' Non-Lexical Vocables PhotoThe real world can be a harsh environment for your project when it's ready to leave the work bench.
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This is a typical circuit power supply connection. the power supply could be a battery, a vehicle power supply or an AC adapter. With a circuit of the first type, there is no protection against reverse polarity, over voltage or under voltage. Compact RFID readers. Reverse voltage protection with a P-FET. Learning Electronics — 1. Astable Multivibrator « Rayshobby. This is the first article in a series that I call ‘Learning Electronics’.
The goal is to learn and experiment with basic electronic circuits. The first circuit I will discuss here is the astable multivibrator. This is a very simple oscillator circuit that can be used to generate square waves. Here is the schematic of a standard astable multivibrator: It consists of only two NPN transistors (T1 and T2), two capacitors (C1 and C2), and four resistors (R1-R4), organized in a symmetric fashion. Update: as some readers pointed out, for square wave output, the resistor values should satisfy: R2 / R1 < h_fe, where h_fe is the transistor's current gain (same for R3 and R4). Principles So how does the circuit work? Stage 1 During this period, T2′s collector (output O2) remains low, and C2 begins to charge through R3. As C2 continues to charge, a critical moment will happen when its left lead rise up to 0.7V, at which moment transistor T1 will turn on, and its collector will conduct to ground.
App note: Understanding Schmitt triggers. Most logic ICs require fast transitions between levels to function properly, while the switch is being made the IC draws additional current, and if it is kept in this intermediate state failure of the chip is possible.
Phase detector. Four phase detectors.
Signal flow is from left to right. In the upper left is a Gilbert cell, which works well for sine waves and square waves, but less well for pulses. In the case of square waves it acts as an XOR gate, which can also be made from NAND gates. On the middle left are two phase detectors: adding feedback and removing one NAND gate produces a time frequency detector.
The delay line avoids a dead band. A phase detector or phase comparator is a frequency mixer, analog multiplier or logic circuit that generates a voltage signal which represents the difference in phase between two signal inputs. Detecting phase difference is very important in many applications, such as motor control, radar and telecommunication systems, servo mechanisms, and demodulators. Types[edit] Analog phase detector[edit] The phase detector needs to compute the phase difference of its two input signals. Assume that the phase differences will be small (much less than 1 radian, for example). See also[edit]