Driving LED – things everyone needs to know

Light Emitting Diodes, more frequently known as LEDs, are semiconductor devices that convert electricity into light. It was hard to find a gadget or other device that doesn’t use LEDs. They are cheap, they are simple to use, and they are small. LEDs can emit different light colors depending on other chemical compound material in a semiconductor. LED symbol One and universal LED symbol is as standard diodes but with a couple of arrows indicating that it emits light:

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Zener – one diode for many uses

Zener diodes are specially designed diodes (heavily doped) that have low reverse voltage breakdown. Due to this characteristic, Zener diodes are connected backward to regular operation. If Zener is forward biased, it acts as an ordinary diode with a forward voltage drop at 0.6V. Zener diode backward voltage breakdowns may range from 2.4V up to 100V. Honestly speaking, if you need like 1.2V, then probably you need to connect two forward-biased diodes in series for 0.6V+0.6V = 1.2V drop.

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Rethinking AVR DDS3 signal generator project

These things happen all the time. When you start a new project but from the beginning start feeling that it’s not what you wanted. Usually, they end up collecting dust. I think there is nothing shameful because it is better to fail than do nothing. There are thousands of examples where people start new projects with enthusiasm, but they never reach the daylight. But without those efforts, we wouldn’t see other great projects and products. Not all of them are made from the first try. It’s been over a year since the announcement of the AVR DDS3 signal generator. As you have noticed, there is no progress so far on it. And I am going to give up on it for a couple of reasons. From the beginning, I didn’t feel comfortable with it.

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Understanding 1-wire interface

1-wire devices. DS18B20 and iButtons

1-wire devices are commonly used in many applications. You probably are familiar with the famous DS18B20 digital temperature sensor in the TO92 package. They can be powered and interfaced using the same single data line plus the ground return, of course. 1-wire originally was designed by Dallas Semiconductors Corp., which is also a major provider of 1-wire devices like temperature sensors, timers, real-time clocks, memory, and the well-known iButton. 1-wire interface is a bidirectional, half-duplex slow serial communication standard. It doesn’t use any clock signal. When talking of speed, the standard data rate is 15.4kbps. But there is possible to overdrive 1-wire communication to up to 125kbps.

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Thermoelectric effect and modules

thermoelectric cooler

Thermoelectric devices are seen very often in various appliances: small refrigerators, semiconductor chip coolers, medical chillers. The thermoelectric effect works in both directions – it can generate temperature difference when current flows, or it can induce current when the temperature difference is applied. About thermoelectric effect It is known for more than 100 years. Several scientists discovered this effect in one or another way. Probably you’ve heard the Peltier effect. Jean Charles Athanase Peltier discovered that if you apply an electrical current to two materials’ junction, it gets cold or hot (depending on current direction).

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Did I just increase DS1022CD bandwidth four times?

Probably you are already familiar with the famous DS1052E hack where guys were able to double and even triple bandwidth. It happens that on my table is DS1022CD scope with 25MHz analog bandwidth. And this hack doesn’t apply to my model. We all know that the same series Rigol oscilloscope models tend to have identical hardware, whether 25MHz, 50MHz or 100MHz analog bandwidth. Of course, the sampling rate (400MHz) stays the same. So it all lies in the software. I felt that someone would figure out how to do this with this pretty old oscilloscope. And here it is – a hackaday pointed to a piece of great news – a simple way of changing the model from DS1022CD to DS1102CD, which converts analog bandwidth from 25MHz to 100MHz. This is quite a step without spending a penny. Andreas Schuler (aka Krater) shared a simple method of doing this without using any serial interfaces and firmware updates. By following his step by step guide, you can do this as follows:

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Diodes – how to choose one

Diodes are semiconductor devices commonly used for many purposes. In general, you can imagine a diode to be a valve that passes current in one direction and stops it from flowing back. The first thing that comes to mind – this might be a good choice for reverse voltage protection. In reality, things are a bit different. First of all, diodes aren’t perfect devices. They have a so-called forward voltage drop, which is about 0.7V for standard diodes. If inserted diode into the power supply, say 5V, the after protection you will get 4.3V where part of voltage is lost in the diode. If you want to go this way, choose the Schottky diode instead, which has a smaller forward voltage drop. A forward voltage drop occurs when the diode is forward biased what means current flow from anode to the cathode.

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The impact of touch screen on gaming

Touch screen technology has been on the market for a while now – specifically for gaming devices – although it’s only in the last 10 years that this translated to mobile technology. It has boosted online gaming numbers because of the ease of use on mobile phones, but how exactly has touch screen technology improved? The primary type of touch screen currently used in mobile technology (especially the iPhone) is a capacitive screen; these work with anything that holds an electrical charge – including human skin. They’re made up of materials that hold charges in an electrostatic grid of either a surface or projective screen. Resistive screens are analog devices that create a connection between two flexible resistive screens. They use your finger’s pressure to create a change in the flow of electricity; when a finger is placed on the mobile, a voltage drop is registered that allows the screen to work.

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Testing LCD keypad Shield for Arduino

arduino lcd keypad shield

Recently I’ve got an Arduino LCD keypad shield. I haven’t decided yet where it will be used. But why not plug it into an Arduino board and see it working. The shield was initially introduced by DFRobot, who has some cool open-source stuff, including robotics-related. This LCD keypad shield is a cheap and convenient solution for adding 2×16 LCD and five push buttons (+1 reset) to Arduino design. LCD here is interfaced using 4-bit mode and occupies 4 (D4), 5 (D5), 6(D6), 7(D7), 8(RS), 9(E), and ten digital pins. Pin 10 is used to control the LCD backlight through the transistor key. All five buttons are connected to a single Analog pin 0 using a resistor-based voltage divider. This lets us keep other pins for general use. The shield is designed to work with 5V based boards.

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Thoughts on interfacing piezo vibration sensor

piezo vibration sensor test with oscilloscope

Some time ago, I purchased a MiniSense 100 Vibration sensor. I probably had some project in mind, but it happened that it dived into drawer among other “to do” things.  I thought it’s time to try a few things with it. Piezo sensor MiniSense 100 is very sensitive with a pretty good frequency response and is linear (±1%). As you can see, high sensitivity is achieved with a 0.3-gram inertial mass at the end of the film. As there is a hole in the mass, you probably can screw in an additional mass and increase sensitivity even further. Probably there is no need to explain where such a sensor would be helpful. These could be vibration/ motion sensors, impact sensors, and other areas where motion and acceleration are involved. Usually, sensitivity is 1V/g. Where g is standard gravity or standard acceleration due to free fall and is equal to 9.80665m/s2. As a mechanical device, it also has a resonant frequency of 75Hz. At this point, sensitivity reaches 5V/g.

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