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Dynamometer Type Wattmeter This is also similar in design and principle to the dynamometer type ammeter and voltmeter. Pic 1 Construction: In the dynamometer type instrument is used as a wattmeter, the fixed coil, which is divided into two equal portions, the fixed coils are connected in series with the load and carry the circuit (or load) current, therefore it is also called as current coil. The moving coils is connected across the load and carries the current proportional to the voltage across the circuit. Therefore, it is known as pressure coil or potential coil. A high non-inductive resistance ‘R’ is connected in series with the moving coil to limit current through it. The magnetic field of the fixed and moving coils react on one another causing the moving coil to turn about its axis. The movement of the coil is controlled by hair springs also lead the current into and out of the moving element. Damping torque is provided by the air friction. Working: When the instrument is connect...

I had previously used the Adafruit TFT display using my library (ported from the Adafruit Arduino library). I decided to optimize the library to improve drawing speed. The same display I use comes with a 4-wire resistive touch-screen as well. I decided to write a simple library for the touch-screen and give Protothreads a try. To incorporate all this, I thought it would be cool if I used these to make a simple game. Tic-tac-toe came to mind as a fun little demo. I'm sure everyone's familiar with the game so I won't explain the rules there. The touch-screen is simply two resistive sheets placed on top of each other on top of the TFT screen. When it is pressed down at a given place, the two sheets make contact and a voltage divider is formed. Using the IO's and the ADC, this voltage is read in the X and Y directions to register a touch. Here is a very good pictorial depiction of the resistive touch screen (taken from the Atmel AVR341 document ): So in order to read the to...

So what kind of auto sound system really seems to float your boat? Are you the type of person who wants the simplest sound system on the market today? Will you be content with talk radio and a few FM radio stations? Do you need an 8-track? How about a cassette player? I hate to say it, but if you are still living in the past, you will have a rather difficult time finding an audio system for your car that can accommodate your desire to hold technology behind the current trends. These things simply do not sell. You may find an occasional auto sound system that still has a cassette player but for the most part you will find that the market for this device is almost as limited as the quality of the device itself. Today's auto sound systems are more sophisticated than they have ever been before. Gone are the days when you had to turn a dial to find a radio station. Today you can set your car to scan the stations until you find one you like. You can even set them to scan radio stations b...

Function Generator The function generator is a versatile instrument that gives a number of different waveforms at the output with their frequencies that can be adjusted over a wide range. The most commonly used waveforms are sine wave, square wave, triangular wave and the saw tooth wave. Different output signals from the function generator may be available simultaneously. Picture of Function Generator The fig shows the block diagram of a function generator. Here two constant current sources are used to feed the integrator circuit. When the circuit is switched ON, the upper constant current source sends a constant current into the integrator and the output of the integrator is connected to comparator. When the integrator output reaches a predetermined level, the comparator changes the state i.e. the upper constant current source is cut OFF while the lower source is switched ON. This current source passes a current in the reverse direction and the voltage at the integrator output decreas...

CASE STUDY, IMPLEMENTATION AND EXAMPLES OF I2C 1. ) I²C is a multi-master protocol that uses 2 signal lines. The two I²C signals are called ‘serial data’ (SDA) and ‘serial clock’ (SCL).The data rate has to be chosen between 100 kbps, 400 kbps and 3.4 Mbps, respectively called standard mode, fast mode and high speed mode.Each device can be a transmitter, a receiver or both. 2.) Some devices are masters – they generate bus clock and initiate communication on the bus, other devices are slaves and respond to the commands on the bus. In order to communicate with specific device, each slave device must have an address which is unique on the bus. 3) Physically, the I²C bus consists of the 2 active wires SDA and SCL and a ground connection. The active wires are both bi-directional. 4) Start Stop Conditions and Data Transfer - Each I2C command initiated by master device starts with a START condition and ends with a STOP condition. For both conditions SCL has to be high. A high to low transition...

This circuit using a dual-timer NE556 can produce 1Hz pulses spaced 5 seconds apart, either manually or automatically. IC NE556 comprises two independent NE555 timers in a single package. It is used to produce two separate pulses of different pulse widths, where one pulse initiates the activation of the second pulse. The first half of the NE556 is wired for 5-second pulse output. When slide switch S2 is in position ‘a’, the first timer is set for manual operation, i.e. by pressing switch S1 momentarily you can generate a single pulse of 5-second duration. When switch S2 is kept in ‘b’ position, i.e. pins 6 and 2 are shorted, timer 1 in NE556 triggers by itself. The output of the first timer is connected to trigger pin 8 of second timer, which, in turn, is connected to a potential divider comprising resistors R4 and R5. Resistor R1, preset VR1, resistor R2, preset VR2, and capacitors C2 and C5 are the components determining time period. Presets VR1 and VR2 permit trimming of the 5-secon...

Modifying USB OTG Cable - Mini USB - micro This is a very simple way to change the standart USB to USB OTG. The Mini or Micro USB to USB does not work if you want to use it for OTG, because 4. pin micro USB plug is not plugged. Connect as shown above.

CHALLENGES DESIGN OF SWITCHING LED ELECTRONIC DIAGRAM The LED WEBENCH® online design environment predicts and simulates the response of an LED to constant current while taking into account several potential design parameters that are new to designers of traditional switching regulators.

A photoflash unit has a simple circuit design: a high-voltage direct current (DC) supply is connected in series with a high-resistance resistor (which we’ll call ‘R1′). This resistor limits the current flow. A capacitor ‘C’ is connected in parallel with a flash lamp. The resistance ‘R2’ of a flash lamp is of small value. The circuit contains a switch between the large resistance ‘R1’ and a small resistance flash lamp ‘R2’, such that it can connect either resistance at any time during the process. [ ]

Remote Audio Level Indicator Circuit Diagram. The normal level-indicator circuits which are available in the market require connections to be made to the output of the player, which may not be easily accessible. The audio level indicator circuit described here removes this restriction as it may be placed close to the player’s speakers and yet the desired effect can be realized. Remote Audio Level Indicator Circuit Diagram : Remote Audio Level Indicator Circuit Diagram As shown in the circuit, signals are picked up by the condenser microphone, which get further amplified by the noninverting amplifier built around one of the four op-amps of LM324. The remaining three, along with four op-amps of the second LM324, are used as seven comparators to work as the level detector, giving seven output levels through seven coloured LEDs.  The sensitivity of the audio level indicator circuit may be improved by varying the 220k potentiometer. If a fine adjustment is desired, a 4.7-kilohm potent...

Advantages and Disadvantages of Transformer Coupled Amplifiers Advantages: 1.        No signal power is lost in the collector or base resistors. 2.        An excellent impedance matching and can be achieved in a transformer coupled amplifier. 3.        Due to excellent impedance matching, transformer coupling provides higher gain. 4.        D.C isolation between first and second stages. Disadvantages: 1.        It has a poor frequency response. 2.        The coupling transformers are bulky and fairly expensive at audio frequencies. 3.        Frequency distribution is higher i.e. low frequency signals are less amplified as compared to the high frequency signals. 4.        Transformer coupling tends to introduce hum in the output. 5.    ...

Definition of power amplifier A transistor amplifier which raises the power level of the signals that have audio frequency range is known as transistor power amplifier. In general the last stage of multistage amplifier is the power stage. A power amplifier differs from the voltage amplifier. A transistor that is suitable for power amplification is generally called as power transistor. Classification of Power Amplifier The power amplifiers can be classified in the following ways. 1.        According to the usage of Frequency Signals: (i)                   Audio frequency power amplifiers. (ii)                 Radio frequency power amplifiers. (iii)               Video frequency power amplifiers. 2.        A...

Introduction  Purpose of a communication system: convey information through a medium or communication channel. ◊    The information is often represented as a baseband signal, i.e. a signal whose spectrum extends           from 0 to some maximum frequency. ◊     Proper utilization of the communication channel often requires a shift of the range of baseband         frequencies into other frequency ranges suitable for transmission, and a corresponding shift back to     the original frequency range after reception. ◊    A shift of the range of frequencies in a signal is accomplished by using modulation, which is             defined as the process by which some characteristic of a carrier is varied in accordance with                 modulating (signal) ◊      A common form of the carrier is a sinusoidal wave, in which c...