Category Archives: Guides

The ins and outs of Peltier Cells

What Are Peltier Cells and How Do They Work?

If you join two dissimilar metals by two separate junctions, and maintain the two junctions at different temperatures, a small voltage develops between the two metals. Conversely, if a voltage is applied to the two metals, allowing a current to pass through them in a certain direction, their junctions develop a temperature difference. The former is called the Seebeck effect and the latter is the Peltier effect.

Many such dissimilar metal junctions are grouped together to form a Peltier cell. Initially, copper and bismuth were the two dissimilar metals used to form the junctions. However, more efficient semi-conductor materials are used in the modern Peltier cell. These are sandwiched between two ceramic plates and the junctions are encased in silicon.

Just as you could pass electric current through a Peltier cell to make one of its surfaces hot and the other cool, so could you place a Peltier cell in between two surfaces with a temperature difference to generate electricity. In fact, BMW places them around the exhaust of their cars to reclaim some electricity from the temperature difference between the hot gases emanating from the car and the atmosphere.

Another place where Peltier cells are put to use is the picnic basket. It connects to the car battery and has two compartments – one to keep food hot and the other to keep food and drinks cool. Unfortunately, Peltier cells are notoriously inefficient, since all they do is move heat from their cold side to the hot. Part of their efficiency is also dependent on how fast heat is removed from their hot side. Usually, Peltier cells are able to maintain a maximum temperature difference of 40°C between their hot and cold sides.

Active heat sinks use Peltier cells to keep CPUs cool inside heavy-duty computers. These CPUs pack a lot of electronics inside their tiny bodies and generate huge amounts of heat when working at high frequencies of a few Giga-hertz. Peltier cells help to remove the heat from the CPU and keep the temperature constant. One advantage in using Peltier cells for this work is the CPU can regulate the amount of heat removed. The CPU in a computer has temperature sensors inside and when it senses its temperature is going up, it pumps in more current into the Peltier to increase the heat removal.

What does the Peltier do with the heat it has acquired from the hot source? To maintain its functioning, the Peltier has to transfer this heat to the material surrounding its hot surface. Usually, this is an Aluminum or Copper heat sink, which then transfers the heat to the atmosphere.

Active heat sinks that are more exotic use heat-conducting fluids to transfer the heat away from the hot side of the Peltier cell. These are specially formulated fluids with high thermal conductivity running in pipes over the hot surface of the Peltier. As the Peltier gets hot, the fluid takes away the heat and changes to a liquid of a lower density. Convection currents are set up, causing the hot liquid to move away to be replaced by cooler liquid, aiding heat transfer. Heat from the hot liquid is removed in a heat exchanger in a different part of the computer.

Parental Control V-Chip – What is it and how does it work?

Parents are concerned over the type of programs their children watch on the television and would like to exercise their control. They do not want their children watching programs with excessive violence or sexual content. Since it is not possible to be always present when the children are watching TV, it is best to have a device automatically detecting the type of program coming through, and blocking it if it is objectionable.

All television sets made and sold in the US after 1999 have a special electronic chip built in and this is the V-chip. This allows parents to select the level of violent programs, which children can watch in the home. This also means that all TV programs contain a rating transmitted along with the program, which the V-chip can detect.

The FCC defines the ratings as –

TV-Y – Suitable for all children, with no violence and no sexual content
TV-Y7 – Suitable for children aged seven and over
TV-G – Suitable for general audiences, with no violence, no sex and inappropriate language
TV-PG – Parents to exercise their own discretion
TV-14 – Suitable for children above 14 only, with some violence and sex
TV-MA – Suitable for mature audiences only and may contain sexual situations and/or graphic violence

A parent can program the V-chip with a specific rating, and the chip will block all programs or shows above that rating. For example, if you have programmed a V-chip for a TV-G rating, it will allow all programs with a rating of TV-G, TV-Y7 and TV-Y, and will block all the rest.

All television programs transmit synchronizing signals, which allow a proper build-up of the picture on the screen. The electron beam painting the picture on the screen starts to sweep from the top left corner to the right edge of the screen, turns itself off, retraces itself to the left edge and sweeps again to the right edge, moving down a tiny bit in the process, until it has covered the entire height of the screen. The beam then returns from the bottom right hand corner of the screen to the top left hand corner and the whole process repeats. The vertical and horizontal retrace signals transmitted along with the TV program control all this.

As the signal returns from the bottom of the screen to the top, it follows a number of horizontal retrace lines. The twenty-first line of the horizontal retraces has data embedded in it as specified by the XDS standard. This includes captioning information, time of the day, ratings information and many others.

The V-chip is capable of reading this line 21 data, extracts the rating’s information and compares it with the parent’s allowed rating. Accordingly, the chip lets the signal pass through or blocks it.

The V-chip in the television works in conjunction with the cable box and/or the VCR. You can either utilize the V-chip or turn it off.

Is it safe to buy gray market electronic components?

What Are Gray Market Electronic Components – And Are They Safe To Buy?

Chances are the low-cost rechargeable batteries that you ordered over the net failed after one or two cycles of operation. A closer inspection would have revealed the batteries were already past their shelf life when you received them. Welcome to the world of gray market electronic components, which currently forms about 6 to 8% of the total electronic components market, and makes up as much as $60 billion dollars’ worth.

Not only outdated components, even parts rejected (and preferably destroyed) by manufacturers, find their way in the supply chain. It is only after soldering the components and sending them for testing does the realization sinks in that they are not genuine. In the $300 billion semiconductor industry, such bogus components have an annual impact of up to $20 billion.

Apart from this, the gray market is also a known issue for unauthorized sale of new and branded products diverted from the authorized channels of distribution. The gray market not only makes the high-tech companies suffer, it also affects negatively consumers and other end-users of technology, such as the military and the defense. Products advertised as new and authentic could in reality be refurbished after use. They could even be counterfeit. Using counterfeit or non-conforming parts could have significant effects on the performance of the product. In the case of defense and military, these effects could also be catastrophic.

Components Direct recently conducted a study for a leading semiconductor supplier. They found over 90 million units of the products, both analog and digital devices, with over 7,000+ part numbers, were floating in the gray market. Over 80% of the products were in the Asian gray market, and 8% appeared in the EMEA (Europe, the Middle East and Africa) and North America. More than 29% of their gray market product had date codes of less than one year, although the product age spanned several years. Nearly 15% of these products had date codes more than 11 years old.

This demonstrates that no end consumer is immune to unauthorized products, irrespective of whether you are a military sub-contractor searching for obsolete components, or an OEM (Original Equipment Manufacturer) looking for new products.

As the chain of supply has numerous potential points of entry, and the ability to trace the path of the product flow remains limited. This makes the gray market problem a prevalent one in most product categories. The multiple points of entry provide unlimited opportunities for unscrupulous individuals, partners or counterfeiters.

The impact of the gray market is significant and long-term. This affects the revenue, cost, brand reputation, liability and risk of the entire chain of supplies. After sales support for the product may be non-existent or it may affect the company’s profitability to maintain support since no one has paid the applicable support. This also affects the end-user operationally and financially, and it may tarnish the manufacturer’s reputation because of the lowered satisfaction of the end-user with the brand

So how do you protect yourself? Look for component suppliers that are stocking distributors. Take to the search engines to see if there are reports of the supplier having supplied bad or counterfeit parts in the past. If you are unsure, buy a sample and have it tested. While there are some scammers out there, there are also many honest and hard-working small businesses that deserve your business.

Do surge protectors save energy?

Most modern electronic gadgets are not meant to be switched off. Rather, they are placed in a state of suspended animation called standby. Gadgets in standby perform some basic background functions until their user recalls them for full functionality. The benefit to the user is an instant response from the unit against having to wait for it to resuscitate.

However, all this comes at a price. Units in standby mode need power, however small, to keep them ticking. For those powered from a battery, need to replace or re-charge their batteries more often. Those drawing power from the utilities’ outlet, consume a tiny amount of power in the standby mode, and if the design of the gadget is not proper, this may amount to energy up to one-tenth of their normal consumption when fully operating. Multiply this with the number of such gadgets all over the house or office, and you will notice the standby consumption forms a substantial chunk of the yearly electricity bill.

People use surge protectors to save their expensive electronic gadgets from going bust with high-voltage surges appearing on the power outlets in homes and offices. These are long strips of connectors allowing plug-in of multiple gadgets. Equipment connected to these strips are saved from the marauding surges because the strip has a device called an MOV inside it followed up with a fuse. The MOV shunts the high-voltage surges and prevents them from reaching the plugged-in equipment.

Apart from the connectors, MOV and fuse, the surge protector strip also has a master switch with which all the gadgets connected to the strip can be switched on or off. Irrespective of the individual gadgets being in full operation or in standby, flipping the master switch to the off position cuts off power to all equipment connected to that strip. This essentially means none of the equipment can draw any more power, not even for their standby operation.

Switching off all equipment from the wall outlet with their individual switches can be a daunting task, especially if there are a number of gadgets connected and the wall outlet switches are difficult to access. After a few days of diligence, people usually give the switching off routine a miss and the equipment remain in a standby mode, consuming their share of energy.

Since surge protectors have a master switch, it is simpler to switch off a number of gadgets at a time, and thereby, cut down on the consumption of standby power. For example, you may have a TV, a few computers, a printer and a few battery chargers hooked up to one surge protector strip. When leaving at the end of the day, switching off individually would be troublesome. However, flipping the master switch on the surge protector strip may not be a big deal.

Therefore, the proactive user is actually saving the energy by remembering to flip the switch on the surge protector strip. If the user forgets to flip the switch, the surge protector strip does not save any energy.

Protection with Surge Protectors – Why and How

If you have once had your TV, audio system and other electronic equipment destroyed by a voltage surge during a thunderstorm, you will surely know how to prevent this from happening once again. For preventing such drastic accidents, it is common to use a device called the surge protector, and to have the maximum protection, it is important to know why it is required and how it works.

Most people know of a surge protector as a long strip of electrical power connectors, which power sensitive electronic gadgets. However, two components inside the strip provide the actual protection. One of them is the Metal Oxide Varistor (MOV), and the other is the familiar fuse. The combination of an MOV and the fuse protects your electronic gadgets by limiting the voltage delivered.

Normally, all households and offices experience power surges many times during the day, including at night. The surges are generated when nearby appliances are switched on or off. Appliances such as microwave ovens, air conditioners, refrigerators and pumps switch on and switch off periodically. When they switch, they create a disturbance in the electrical supply lines, causing either a voltage dip or a voltage spike, or both. Since all electronic gadgets have a limit to the level of voltage they can withstand, any spike over and above the limit will have a damaging effect.

A thunderstorm is another factor generating a power surge. Even if lightning does not strike a home directly, it is enough if it hits a power line nearby. The power lines feeding a home can carry this surge in and can cause massive damages. Using a surge protector largely prevents all this.

The MOV inside a surge protector has a special property. As long as the voltage across it does not cross its specified limit, the MOV remains a passive device, with a very high resistance. When a surge arrives, and is above the voltage limit, the MOV lowers its resistance immediately. This causes a massive current to flow through the MOV. The increased current also flows through a fuse, which precedes the MOV, causing the fuse to blow and cutting off any further supply to the MOV and any connected gadget. In the absence of a fuse, or the fuse not blowing because of improper rating, the MOV may burn out allowing further spikes to be passed on to the gadget.

An MOV has a specific voltage rating and the spike expected at the point of use defines the rating selected. The telephone industry uses a special type of surge protection, known as Gas Discharge Tube or GDT, at specific points where the telephone lines enter a building. A GDT operates at a much higher voltage as compared to an MOV, and offers protection from higher voltage surges.

For working satisfactorily, an MOV and a GDT both need a good electrical earthing and a proper earth-wire connection.

What is a battery and how do they work?

CR2032 battery

Batteries power most of our mobile gadgets. These are small chemical powerhouses, which generate electricity by the chemical reaction within the battery housing. Although there are different types of batteries available, all batteries contain cells that have two electrodes and a chemical or an electrolyte between them. Various combinations of series and parallel connections of the electrodes make up a certain voltage rating for the battery. For ease of understanding, we will treat the battery as made up of a single cell.

One of the electrodes is the cathode or the positive (+) terminal and the other is an anode or the negative (-) terminal. Because of the reaction between the two electrodes and the electrolyte inside, there is a buildup of electrons at the anode and a corresponding lack of electrons at the cathode. Although this is an unstable condition, and the electrons want to distribute themselves evenly between the electrodes, they cannot do so because of the presence of the electrolyte and its reaction with the electrodes. An isolated battery soon reaches a chemical equilibrium, and no further reaction occurs.

If the electrons find an alternate path to travel from the anode to the cathode, they will redistribute themselves and the number of electrons will gradually reduce, forcing the chemical reaction to start over again and create more electrons. This process continues until an inert layer covers one or both the electrodes. Usually, the alternate path is through a metal wire, which is a good conductor of electricity and links the two electrodes of the battery through a load or the mobile gadget requiring power.

Electrons flowing from the anode of the battery through the external wire to the load and back to the battery cathode constitute an electric current. Since it is usual to consider the direction of current flow as opposite to that of electron flow, we commonly say current flows from the cathode of the battery through the load and back to the battery’s anode.

Since the physical size of the battery restricts the quantity of chemical inside it, the current produced by the battery is also limited. The battery specification, as mAH or AH, is the product of the current and the number of hours the battery can produce this current continuously. In general, once the chemical within the battery has depleted itself or inert material has covered up the electrodes, the battery becomes useless. However, it is possible to revive or recharge certain types of batteries. These are the rechargeable batteries.

Once a rechargeable battery depletes itself, you can charge it up again by sending a current through it in a direction reverse to what it normally produces when connected to a load. This reverses the chemical reaction inside, and the electrolyte and the electrodes return to their initial condition. You can repeat this discharging and recharging process many times, until the electrolyte exhausts itself totally, and no further revival is possible.

Tracking sleep, activity & food – the Jawbone UP app

Imagine being able to track every calorie you burn, every calorie you consume and every minute you are sleeping? We came across the Jawbone UP and are just amazed at the capabilities this app possesses. It needs to be coupled with the UP wristband to function (available on their site for about $129 or on ebay for less than $100). The app is compatible with iPhone and Android.

Here’s some of the amazing features:

Sleep and nap tracking – it tracks your sleep including the amount of light sleep vs deep sleep.

Power Nap – need a power nap? UP will let you get one in and wake you up after the perfect amount of sleep is achieved (26.5 minutes according to the UP web site).

Smart Alarm – UP will wake you up at the best possible time in your sleep cycle – this will help you feel more awake and refreshed.

Food and Drink Tracker – helps you keep track of what you eat and drink to get the whole picture of your health.

Activity Tracker – UP tracks every calorie you burn, every activity you do.

There are many more features (like a mood tracker) that you can also monitor but the bottom line is that this system helps you keep track of every bit of your lifestyle and delivers information to help you live a healthier life and encourages you to keep moving forward. Sound interesting to you? We’re hooked! We love the idea and are placing our order today for our first one. We’ll keep you posted on our experience with it.

11 secret controls on your iPhone headphones

If you have any Apple brand device, chances are you have at least one pair of their headphones laying around. If you use them on a regular basis, here are some tips to get the most from your Apple headphones:

During phone calls:
1 – Incoming calls: Tap the center button to answer a call
2 – Ignore a call: Long-press the center button to ignore the call – you should hear 2 ‘beeps’ and you will know that the caller was successfully sent to voice mail
3 – Swapping calls: Tap the center button once to swap calls – Hold the center button down for about 2 seconds to end the new call
4 – Disconnecting/Hanging up: Tap the center button once again to hang up

When listening to music:
5 – Toggle pause/play: Single tap the center button
6 – Skip a song: Double tap the center button
7 – Return to the previous song: Triple tap the center button
8 – Fast forward a song: Tap the center button two time; long-press the second tap
9 – Rewind a song: Tap the center button three times; long-press the third tap.

Using the camera function:
10 – Shutter Release: Tap the volume-up button to snap a picture. This trick will help you get very steady shots.

For Siri users (iPhone 4S and above):
11 – Activate Siri: Long-press the center button

Remember – any Apple device that utilizes their headphones and have these functions (i.e. iPad and iPod) can also take advantage of these features. Do you know of any headphone tricks that we’ve missed? Send them our way!

Motor Start Capacitors vs Motor Run Capacitors

We are often asked about the difference between the two different types of motor capacitors: motor run and motor start. Here are the basic differences between the two:

Motor Start Capacitors
The primary purpose of a motor start capacitor is to briefly increase the motor starting torque as well as to allow a motor to be cycled on and off very quickly. It operates in the circuit by staying active long enough to allow the motor to be brought to 3/4 of it’s full capacity. It is removed at that point by a switch in the circuit. You will find that the voltage rating is often one of these four: 125VAC, 165VAC, 250VAC, and 330VAC.

Motor Run Capacitors
Motor run capacitors will then operate after the circuit is started. Using a motor run capacitor will run the motor with greater efficiency. Motor run capacitors are designed for continuous duty. They are energized while the motor is in operation. You will often find motor run capacitors with a voltage rating of 370VAC or 440VAC with a capacitance of 1.5uF – 100uF. Typically, the construction material is polypropylene film.

Operational information
Electric motors that are single phase require a capacitor for a second-phase winding. If you use the wrong motor run capacitor, the rotor may hesitate due to an uneven magnetic field. The hesitation may result in performance issues such as a noisy or overheated motor, increased energy consumption and general decreased performance.

Faulty motor capacitors
You can sometimes spot a faulty motor run capacitor by it’s swollen appearance – or it may have blown and become leaky. Of course, these capacitors should be carefully replaced. In addition to an outright capacitor failure, the capacitance may become reduced over time. Capacitors that are operating with a decreased capacitance may create performance issues. Again, these capacitors should be carefully replaced.

Take better pictures with your cellphone camera

Whether you have an iPhone, Android or any other phone with a camera, here are our top 3 tips for getting better pictures with every shot.

1 – Composition:
Even with an entry level camera phone, remember the basic rules of composition when taking cell phone pictures. The rules of thirds is important: don’t place the subject of your photo in the middle of the frame. Place your subject in about 1/3 of the way into the frame. Also, if you are photographing people, line up your shot so that their eyes are about 1/3 from the top of the frame.

Another tip for composing great photos is to declutter your background. Taking a picture of your new car? Be sure your garbage can is put away. Compose your backgrounds to tell a story. A day at the beach can be told in pictures with the sun, sand and surf behind your subject. If you can, change your perspective – always shooting from a standing position will never get you the best angle for the best possible picture.

2- Blurry pictures:
The most common problem with digital pictures is that the camera is not held steady which often produces a blurry pic. Brace your arm on a table or against a wall. If there is no table or wall in site, tighten your arms against your body and hold your breath as you take the photo. Release your breath as you take the photo.

3 – Lighting:
Poor lighting can produce blurry pictures, poor color and shadows. Whether you have a flash or not on your camera phone, be sure to compose your pictures to get the best light possible. Stay away from bright sunlight – that will create pictures with harsh shadows. Instead, compose your pictures in the shade. While this will result in a darker photo, you will have a more even tone without the harsh shadows caused by direct sunlight.

If you are indoors, try to keep curtains open and the lights on – but keep your subject from being right under bright lights. It is better if the light is all around the room rather than right over your subject.

With these tips and some practice, you will be able to take great photos on your camera phone.