Electronics Archives - Page 5 of 9 - Do It Easy With ScienceProg

What are MEMS

Today MEMS is a common acronym among engineers. Therm MEMS stood for micro-electro-mechanical system and was started to use in 1980sin USA. MEMS are called systems because they are sensors and contain electronic circuitry inside which conditions sensor signal. Simply speaking, MEMS is usually a chip device that integrates mechanical elements, sensors, actuators, and electronics. Most interesting and important partis mechanical. Miniaturizing the mechanical parts using micro-machining technology when selectively parts are etched away, it became possible to create mechanical structures on silicon base and electronic devices. MEMS devices are used everywhere today, including automotive, industrial even computer hard drives with MEMS sensors for shock protection. The ability to integrate mechanical sensors inside the chip made it possible to design compact accelerometers, gyroscopes, pressure sensors, sensors with integrated RF, and many more. Also, technology enables the integration of more than one sensor inside the chip. One example may be 3-axis accelerometers. A major producer of inertial MEMS is Analog Devices, which produce accelerometers and gyroscopes.

Quality music sound in the car

Most of the driver’s car is more than a vehicle. Sometimes people spend hours in the car every day and listens to the news radio broadcast and listens to music. Having good quality music sound in the car requires more than good speakers and power amps, but some smart solutions are also needed to make it sound better. There are plenty of publications on how to DIY a good car sound system at home in the current time. Even the best power amplifier does not guarantee that car music will sound like Hi-Fi class. The main problem is the hard installation of the audio-system inside the vehicle. In many cases, speakers are installed where ever they fit in the car. But there is also no clear answer where it is the best place to install speakers and how. The most common mistake is to place powerful high-quality speakers in the rear shelf while the speaker’s front position is installed or not at all. Such an audio system installation gives a feeling like he is sitting back to the scene.

Switching step-up and step-down regulators

All regular voltage regulators (like 7805) have several disadvantages like output voltage is always lower than input, and some power is dissipated in the control element. Dissipated power is approximately equal to I(Vin-Vout). There is another way to generate a regulated voltage. The method is different from the previous one. A transistor operates as a saturated switch in a switching regulator, which periodically applies the full unregulated voltage across an inductor in short intervals. During each pulse, inductor current builds up, storing energy on its magnetic field: Inductor also smooths the output voltage. Feedback circuit with comparator compares the output voltage with reference and this way changes oscillators pulse width or frequency.

Dual polarity power supply source

Most op-amp circuits run from the symmetrical bipolar supply source, let’s say ±15V. The simplest way to generate symmetrical split supplies is to use a pair of 3 terminal voltage regulators. For instance, let’s take two voltage regulators: 7815 and 7915. If you need an adjustable variant of dual polarity regulated voltage source, you can use 317 and 337 adjustable regulators, where you can trim voltage with a voltage divider, which consists of two higher accuracy resistors:

Fractal antenna constructions

Among the usual antennas used in today’s data transfer, different types of antennas are used. First publications about electrodynamic characteristics of fractal structures were published in the 1980s, but the first practical approach appeared after 10 years. Dr. Nathan Cohen, professor of Boston University, designed, engineered, and patented many practical fractal antenna solutions and founded “Fractal Antenna Systems” in 1995. Van Koch fractal antenna As Nathan states, there were forbidden to use external antennas in the city in the center of Boston. Hence, he managed to hide the antenna within the design of an amateur radio station. He took aluminum foil and made an antenna as decoration according to Van Koch figure:

How to make 5V from 1.5V

In many cases can be very handy to be able to convert 1.5V to 5V. Then you can power a microcontroller or an LED from a single AA or AAA battery. It is simple to do this as there are special IC’s as MAXIM MAX1674 or MAX7176. This is a step-up DC-DC converter that can convert voltages from 0.7V to any in the range from 2V to 5.5V. MAX1676 already has preset pins for 3.3V and 5V, making easier integration in 3.3 and 5V circuits. IC can dissipate up to 444mW. Bellow is a circuit that converts 1.5V to 5V. We need to get the maximum output of the current 300mA; then, we need to put some effort. Because output power is 5V·0.3A=1.5W, let’s say efficiency is 100%, then the power drawn from the battery will be 1.5W too. At 1.5V voltage, this will be 1A current. Not all batteries can drive such currents. Another important part is an inductor. For this wee need inductor with high current saturation, which usually leads to an increase in size.

Ultrasound transducers for measuring distance

Ultrasounds transducers for measuring distances are commonly used in robotics, automotive parking sonars. Ultrasound distance measuring is non -contact measuring method – radiation and reception of ultrasound waves. Ultrasound waves are mechanical acoustic waves with frequencies more than 20kHz. Normally humans cannot hear frequencies above 20kHz, while some animals can. For instance, bats use ultrasound location of objects. Dolphins communicate with each other using ultrasound signals. Ultrasound interacts with a hard body, and part of incoming wave energy is reflected; in other words – it is backscattered. So direct wave towards an object is backscattered widely – up to 180°. If the object is moving – the received frequency differs because of the Doppler effect. Let’s say simple example – parking sonar. Distance to object can be calculated very simply by the formula:

Marking of Digital IC chips

There are currently huge amounts of different digital IC chips available in the market, starting from the simplest logical elements and ending with processors and gate arrays (FPGA). Of course, there also are lots of IC manufacturers offering IC’s. Many of them are specialized and won’t be reviewed here. Let’s limit ourselves to smaller, more general digital chips, basically TTL 74series. This series is produced by many manufacturers like Texas Instruments (TI).Common marking: Manufacturer identifier indicates the manufacturer name;

VGA to X-Y-Z scope converter

This is a fun project I found on Jon’s antique radios web-page. He has managed to convert the VGA output signal from PC to X Y X oscilloscope signal. Converting the VGA RGB signal to a synchronized oscilloscope input signal is pretty easy because VGA has two sync signals separate from RGB signals. Look at pin-out of VGA cable: Sync signals make things much easier as there is no need for additional sync signal generators – thus circuit becomes pretty simple without any programmable components:

RS232 emulates I2C for 24cXX memory programming

Sometimes you need a quick and easy solution for programming serial EEPROM memory chips. I think the easiest and well-known method is to use a simple programmer adapter with very few components: This adapter is connected to the RS232 port, and there is no need for an additional power supply as it comes from the PORT pin. The adapter is compatible with JDM Programmer so that you can use its programming software like IC-PROG. Just make a couple of settings, and you are ready to go: