Electronics Engineering

A varistor is a variable resistor. It changes value dependent on the current draw and operates by changing its value as the resistor's temperature changes. For instance, during turn-on of a device, the resistor heats up causing the resistor to change it's value, thereby limiting the inrush current to the device. Once the initial start-up current is reduced and the device is operating normally, the resistor cools down and changes value again.

Depends on what you need to know about it. First off, I'd use an oscilloscope. If it's set up correctly and you know how to `count graticules' that's really all you'll need to learn almost everything about your oscillator. IT should show you the wave forms at certain connection points, voltages as well as giving you some indication of the frequency. And if you want to know the current draw, you should probably have some type of milliamp meter on hand, which can usually be found in most miltimeters.

variable capacitors are those capacitors which can be intially or randomly canged by the user for example radio tunning.whereas fixed capacitors are those whose value is fixed and can't be changed. sohaib

Electrons don't have electricity they only posses energy, Electricity is defined as the flow of electrons! In conductors the flow of valence electrons are called Electricity! therefore inducing a current in it! generally the direction of flow the current is the opposite of the direction of flow of electrons(D.C)!

what is the function of ic 4017 in clapswitch?

hey i have mint pics step by step how to do it my e mail is pmeigeljr@yahoo.com

Low insulation resistance causes power loss in that system. That's a direct loss. If you're paying for something like gasoline and it's leaking out the hose you use to get it into your vehicle, you don't get all you pay for. And then there's the distinct possibility that damage to the distribution system can result and further degradation of the conductor/insulator bundles can occur. The second thing could be a killer. There's always the possibility of a fire. That'd be bad.

The Bipolar Junction Transistor (BJT) was invented by three scientists, William Shockley, John Bardeen and Walter Brattain, in 1948. They all worked at Bell Labs, and were trying to find something to replace the bulky and heat wasting vacuum tubes. They had been pursuing a Field Effect Transistor (FET) based on copper oxide when they stumbled upon a very different amplifying effect produced by closely-spaced metal contacts touching Germanium semiconductor. They won the Nobel Prize in Physics for their work in 1956.

When the Bell Labs scientists continued to investigate a possible FET transistor, they discovered that one of these had already been patented by Physicist J. Edgar Lilienfeld. Lilienfeld's insulated-gate FET (or MOSFET) was based on thin film semiconductor deposited on glass, and was invented over 25 years before the BJT, in the early 1920s.

Transistor History

http://nobelprize.org/educational_games/physics/transistor/history/

The Transistor Museum

http://semiconductormuseum.com/Museum_Index.htm

Lilienfeld transistor history

http://chem.ch.huji.ac.il/history/lilienfeld.htm

William Shockley, Walter Brattain, John Bardeen

From the research i could do on the internet is seems like all the curuit citites have been completely shut down and they are out of business. Most of the circuit cities have been replaces by a company called HH Gregg

The products that uses the capacitor are filters and oscillators.

A control device, normally used in industrial control applications, that employs the hardware architecture of a computer and a relay ladder diagram language. Also known as programmable logic controller.

There should be a slot in the back that opens up, often with a screwdriver. Put the batteries inside of there, and make sure that you have the correct size and that they are put in correctly with the + and - lining up.

It depends. The 2A current, did you measure that while the soldering iron was on? Or is it rated at 2A current consumption on the device itself (on the powercable or the stem of the soldering iron). Generaly speaking you can calculted the real power consumption by using P=V*I (thus 2A*24V = 48W). But do remeber that this power consumption is in the steady state, that is, after its switch on and all transient effects have died down. To be safe allow for 3A-4A switching currents that occurs at power on.

A 'compund wound' dc generator has shunt winding and a series winding. The shunt winding has a high resistance, and draws only a small current from the armature, but as it has many turns of wire on it, it generates a strong magnetic field. The series winding has only a few turns of wire on it, and, even though it has a large current in it, its magnetic field is usually less than that of the shunt field. Because of this, the compound generator behaves in most ways like a shunt generator, and is controlled in the same way. As it is self-excited, the compound wound generator requires 'residual flux' to start the generating process.

The series winding, if connected to AID the shunt field, can boost the field flux as load comes onto the machine and correct for the normal 'droop' in output voltage as the load increases. If set up properly, this correction makes the generator self-regulating. Because the fields aid each-other, this connection is called 'cumulative compounded'. This type of machine is the workhorse of the larger generator market.

If the series field winding is connected so it's field OPPOSES the shunt field, then the output voltage of the generator collapses as the machine is loaded up. This connection is referred to as 'differential compounded', and is only used for arc welding generators - they have a high voltage before the arc is struck; a fairly low voltage during welding operations, and if the rod sticks to the work, they shut the generator down without damaging it.

It depends on the nature of the transmission line mostly under a fault it is the inductance that will be limiting the fault current so your power factor would be quite low. The exact number would change from line to line.

During a fault (say three phase fault for simplicity), the power factor will drop to the line angle (assume no, or very little fault resistance). On EHV systems, this is in the 80 - 88 degree range (typically). On VHV, it is often in the 70-80 degree range. A line angle of 90 degrees is a pf of 0, so to convert between this line angle and power factor: pf = cos (line angle).

As voltage gets lower, the assumption of no fault resistance becomes less valid, and the line angle becomes less (increased power factor).

The lowest VHV line angle I've seen is in the 60-70 degree range. I've seen 40-60 on HV, and as low as 30 degrees (.86 pf) on underground cabling.

A: Because both item are connected is series. Any resistance connected in series will carry the same current no matter of the resistance value or the number of resistors. However for an incandescence lamp the value will change when turn on and change when it is hot, That is because lamps have different property then resistance when cold and hot

11-15v from batt.

yes

30 ohms.

Noise immunity is the ability of a system to perform even when there is noise present. The higher the level of noise a system can still operate under, the higher the noise immunity.

YES

Well, first of all, voltage is not carried. Voltage is the 'pressure' between the ends of

a circuit that makes charges want to flow. The charge carriers that actually do the

physical flowing are the electrons, with their negative charges. When they flow, we

say that there is 'current' in the conductor.

possibly some of both, as well as various other components.