What is Pyroelectricity?

Pyroelectricity is the ability of certain materials to generate an electrical potential when they are heated or cooled.

As a result of this change in temperature, positive and negative charges move to opposite ends through migration (i.e. the material becomes polarised) and hence, an electrical potential is established.

Pyroelectricity can be visualized as one side of a triangle, where each corner represents energy states in the crystal: kinetic, electrical and thermal energy.

The side between electrical and thermal corners represents the pyroelectric effect and produces no kinetic energy.

The side between kinetic and electrical corners represents the piezoelectric effect and produces no heat.

Although artificial pyroelectric materials have been engineered, the effect was first discovered in minerals such as quartz and tourmaline and other ionic crystals.


Raspberry Pi Vs Intel Edison Features Comparison

HR-OS1 means?

The HR-OS1 is powered by an onboard Linux computer giving you all the processing power you need to run your robot. The HR-OS1 is a hackable, modular, humanoid robot development platform designed from the ground up with customization and modification in mind.

Raspberry Pi Vs Intel Edison

Your HR-OS1 kit shipped with 2 choices for the Main CPU – the Intel Edison and the Raspberry Pi. Both platforms will run the same HR-OS1 framework to control your robot. Each platform has its strong points, as outlined below.

#Intel Edison Pros

  • Power Consumption The Intel Edison consumes far less power than the Raspberry Pi.
  • Size Even with the breakout board, the Intel Edison is much smaller then the Raspberry Pi.
  • Built in Wifi/Bluetooth The Intel Edison does not need extra dongles to add bluetooth / wifi functionality.
  • Built in FTDI USB-Serial Converter You can connect the Intel Edison Mini Breakout directly to you computer to open a serial terminal to control the Edison.
  • More Mature Development/Testing We have been working with the Intel Edison for much longer than the Raspberry Pi, so the framework is better tested with the Intel Edison.

#Raspberry Pi Pros

  • USB Ports The Raspberry Pi has 4 available USB ports to attach devices to.
  • SD Card Slot The Raspberry Pi’s SD based storage makes it possible to upgrade your disk size. Each HR-OS1 kit ships with an 8GB SD card, compared to the Edison’s built in 4gb eMMC storage.
  • Easy access GPIO pins The Raspberry Pi has 3.3v I/O pins that are easily accessible through the male pin headers. The Intel Edison has 1.8v pins.
  • Standard Ports HDMI, ethernet, composite video, and audio ports
  • **Special Ports ** Camera and display interface ports
  • 3d Graphics core
  • Superior processor


SRAM (Static Random Access memory) and Cache (L1, L2, L3)

SRAM (static RAM) is random access memory (RAM) that retains data bits in its memory as long as power is being supplied. Unlike dynamic RAM (DRAM), which stores bits in cells consisting of a capacitor and a transistor, SRAM does not have to be periodically refreshed. Static RAM provides faster access to data and is more expensive than DRAM. SRAM is used for a computer’s cache memory and as part of the random access memory digital-to-analog converter on a video card

CPU Cache

A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, closer to a processor core, which stores copies of the data from frequently used main memory locations.

CPU cache is a smaller faster memory used by the central processing unit (CPU) of a computer to reduce the average time to access memory.
L1 (Level 1), L2, L3 cache are some specialized memory which work hand in hand to improve computer performance.

When a request is made to the system, CPU has some set of instructions to execute, which it fetches from the RAM. Thus to cut down delay, CPU maintains a cache with some data which it anticipates it will be needed.

(L1) Level 1 Cache(2KB – 64KB) – Instructions are first searched in this cache. L1 cache very small in comparison to others, thus making it faster than the rest.

(L2) Level 2 Cache(256KB – 512KB) – If the instructions are not present in the L1 cache then it looks in the L2 cache, which is a slightly larger pool of cache, thus accompanied by some latency.

(L3) Level 3 Cache (1MB -8MB) – With each cache miss, it proceeds to the next level cache. This is the largest among the all the cache, even though it is slower, its still faster than the RAM.

Now you know what cache is and what different level of cache are.
And that 6MB value of the L3 Cache in your Intel 4700MQ microprocessor is actually the memory size of that Cache.
Thus Cache improves the overall performance of the CPU but these numbers shouldn’t be considered while purchasing any system. Look at the benchmarks of the CPU as a whole. A CPU with similar architecture but with more cache wouldn’t make any noticeable difference. The technology these days have advanced to such a point that the specs of a CPU are just meaningless.

Difference Between CD-R and CD-RW

A CD-R is a type of disc that does not contain any data. It is blank so that a user can write his own data into the disk for various purposes, like data storage and back-up. An improved version of that is the CD-RW, which is a disk that can be written on multiple times. The user can erase the content of the disk or write new data into it whenever he likes to, much like the older diskette technology.

The CD-R was made to be compatible with all devices that utilize the same medium, even though the method of writing data into the disc differs slightly compared to traditional CDs. The CD-R was also known as ‘Write Once Read Many’ because of the fact that you can only write to the disc once. This might be a little bit confusing since you can actually write on a CD-R a few times since it allows writing to the disc in increments. The CD-R medium also brought forth its own drive. The CD Writer is a drive that looks and acts like a normal CD-ROM but with the capability to write data into CD-Rs.

What you do on a CD-R is to erase the old data and replace it with a new one. Once the disc is full, you cannot add or replace data on it. That shortcoming has been remedied by the appearance of CD-RW discs. These discs are very similar to the CD-R but have the added feature of being erasable. Erasing the data in a CD-RW disc makes it revert to its old state and can be used just like a blank disc. The technology of CD-RW requires much better optic technologies than what CD-R requires, thus CD Writers cannot write into the CD-RW. Although backwards compatibility means that all CD writers and some of the older CD-ROMs could read a written CD-RW.

CD-Rs do have a few advantages over the CD-RW, one of which is the fact that that the former costs a lot less compared to the latter. CD-Rs are also a lot more reliable in storing data due to the unstable nature of the alloy used in CD-RWs. Read and write times are also significantly higher in CD-RWs causing longer wait for the user. With those arguments, the CD-R and CD-RW are just about even when weighed in. CD-Rs are appropriate for storing data for long periods of time like in back-ups while CD-RWs are excellent when transferring files from one PC to another due to it reusability.


Operational Amplifier based Integrator Circuit

The description contains information such as design details, equations and practical ideas for the operational amplifier or op amp integrator circuit.


  • Operational amplifier circuits
  • Inverting op-amp
  • Non-inverting op-amp
  • High pass filter
  • Low pass filter
  • Bandpass filter
  • Variable gain amplifier
  • Notch filter
  • Multivibrator
  • Bistable
  • Comparator
  • Schmitt trigger
  • Integrator
  • Differentiator

Operational amplifiers form an ideal basis for creating an integrator circuit.

While it is possible to develop a simple integrator circuit using just a resistor and capacitor, the operational amplifier with its high level of gain enables a far higher performance circuit to be created.

The op amp based circuit is able to give much higher levels of linearity, and a much greater elvel of integrity in its output than one using just the minimum number of components.

Electronic integrator basics

In most op amp circuits, the feedback that is used is mainly resistive in nature with a direct resistive path forming at least part of the network. However for the integrator this is not the case – the component providing the feedback between the output and input of the op amp is a capacitor.

As the name of the op amp integrator implies, it performs a function that is an electronic equivalent to the mathematical integration function. In fact electronic integrator circuits can be used in analogue computers.

In terms of their operation, the circuit produces an output that is proportional to the integral of its input voltage with respect to time.

This means that the output voltage at any time is determined by the start output voltage, the length of time the input voltage has been present and the value of the input voltage.

The basic idea behind an integrator circuit is shown below. Although there are a few changes for the op amp integrator circuit, this concept is what is behind its operation.

Integration of voltage
Integration of voltage

From the diagram, it can be seen that while the input remains at zero, so does the output. However when a step input voltage is applied to the input, the output rises. When the step input returns to zero, the output remains at the voltage it last attained.

Operational amplifier integrator circuit

The basic operational amplifier integrator circuit consists of an op amp with a capacitor between the output and the inverting input, and a resistor from the inverting input to the overall circuit input as shown.

Op amp integrator circuit
Op amp integrator circuit

One of the first points to note is that as the signal is applied to the inverting input, the output of the circuit is the inverse of a basic CR integrator network.

Output from op amp integrator circuit
Output from op amp integrator circuit


Design calculations

The primary calculation required for the circuit is to determine the output voltage for a given input voltage for a given time.

Op amp integrator design equation

Vout = output voltage from op amp integrator
Vin = input voltage
T = time after start of application of voltage in seconds
R = resistor value in integrator in Ω
C = capacitance of integrator capacitor in Farads
c = constant of integration and in this case is the output starting voltage.

The negative sign in the equation reflects the inversion resulting from the use of the inverting input of the op amp.


It is obvious that the output of the integrator cannot rise indefinitely as the output will be limited.

The output of the op amp integrator will be limited by supply or rail voltage and the saturation of the op amp itself, i.e. how close to the rails the output can swing.

When designing one of these circuits, it may be necessary to limit the gain or increase the rail voltage to accommodate the likely output voltage swings.

While small input voltages and for short times may be acceptable, care must be taken when designing circuits where the input voltages are maintained over longer periods of time.

Op amp integrator saturation point
Op amp integrator saturation point

Reset facility

It is sometimes necessary to have a means whereby the op amp integrator can be reset to zero.

The addition of a reset facility or capability is very easy to achieve. It is accomplished by simply adding a switch across the integrator capacitor. This has the effect of discharging the capacitor and thereby resetting the overall integrator.

Op amp integrator with reset switch
Op amp integrator with reset switch

The reset switch can be implemented in a variety of ways. Obviously a simple mechanical switch can be used, but it is also possible to use semiconductor switches. These are typically FET based switches because they have a very high off resistance and can be controlled as switches in this type of application more easily.

voltage swing

Swing is the difference of maximum output voltage and minimum output voltage. Maximum possible swing in output you can have is VDD-VSS. where VDD is most positive voltage and VSS is most negative voltage. It does not mean that your swing is VDD-VSS. It may be smaller than this. This depends on circuit design.
For CMOS logic family it is VDD-GND. It means CMOS logic family have full voltage swing.

For example:

Question: op-amp741 why Voutmax= VCC-Vce(sat)13-Vbe14 ? Isn’t it:VCC-Vce(sat)14?

Answer: The output circuitry of op-amps have one transistor pulling the output pin up to +Vcc and another transistor that pulls the output pin down to -Vcc. So the output pin can only go to Vcc – VCE sat in each direction. It is unusual to run a “linear” amplifier right up to the output transistors saturation point, because the risk of lock up (negative feedback turning into positive), so it is safer to allow a margin between the Vout and the VCC.

Rail voltage

A voltage “rail” refers to a single voltage provided by the PSU (short for power supply – actually it stands for power supply unit). An ATX PSU has one 3.3 volt rail. It also has one 5 volt rail. The 3.3 volt rail has its own circuitry in the PSU which generates the voltage.

Rail to Rail Voltage Meaning???

Answer 1:

Rail = DC supply rail.

If the circuit operates with one supply rail and ground – then ground is
considered to be one of the rails.

Answer 2:

A “rail” here is a power supply. Rail-to-rail just means the full
range of voltages between the most positive and the most negative
power supply voltages present.

Most opamps, for example, if powered from +15 and -15 rails, can’t
make outputs that go all the way from +15 to -15… they usually lose
a volt or two on each end. A r-r-output opamp can output almost all
the way.

Simple Real time analogy for rail to rail voltage:

In Inter-Modal Transportation, Rail to Rail means a Bus, just like in
electronics. If I wished to travel by rail from City A to City B, I
might have to take the bus in order to resume Rail travel.

Inter-Modal Transportation Means

Inter-modal means “involving two or more different modes of transport in conveying goods”.

Intermodal freight transport involves the transportation of freight in an intermodal container or vehicle, using multiple modes of transportation (rail, ship, and truck), without any handling of the freight itself when changing modes.