Circuits

First this question contains a common confusion: it is silicon not silicone.

• Silicon is an element on the periodic table, the most common element present in minerals on earth, frequently used in its purified elemental form to make semiconductor electronic devices.
• Silicones are various chemical compounds, equivalent to organic compounds except the carbon atoms are replaced by silicon atoms. Silicones may be oils, plastics, glues, etc. They cannot be used as semiconductors.

Now to answer the question: in 1957 Fairchild Semiconductor opened in Palo Alto, California and began making the first silicon mesa transistors; in 1958 Fairchild Semiconductor developed the planar process, making almost all earlier methods of transistor manufacture instantly obsolete; in 1959 Fairchild Semiconductor made the first monolithic silicon integrated circuit (aka silicon chip) using the planar process. Full production of the first commercial monolithic silicon integrated circuit (a flip-flop containing 4 transistors, called the MicroLogic type "F") began in 1960.

The answer is 1959, with sales beginning in 1960. Take your pick.

-- If you do the sum around a closed loop, the items that are summed

are always the same items. Arithmetically, starting at a different point

is just a matter of lopping a few of them off the bottom of the list and

moving them to the top, before summing them.

-- The sum is always zero anyway, so it makes no difference where you

start or end.

The simplest explanation (and therefore not completely accurate, but it will help you understand what happens) is that as the frequency of an AC signal increases the less able a wire is to contain it.

1. at very low frequencies, including those of powerlines, the current flows easily through the entire diameter of the wire
2. at intermediate frequencies, up to about the AM radio band, the current avoids the center of the wire, only flowing through its surface
3. at high frequencies, including those used for TV, a significant amount of the AC signal escapes from a wire as electromagnetic radiation - the shield on a coaxial cable "reflects" this electromagnetic radiation back to the center conductor, preventing its loss
4. at microwave frequencies AC will not follow a wire at all and the electromagnetic radiation is directed around through metal pipes called waveguides (analogous to a coaxial cable but without a center conductor, only the outer shield to reflect the electromagnetic radiation)

For the use in electrical engineereing:

Generally speaking, using a relay may involve anything from a very robust approach to an extremely delicate approach. Consider some aspects of a relay. A relay has contacts, arcing and sparking because of back e.m.f from load circuits may damage these contacts and reduce the life span of the device. Some inductive applications might require a low value capacitor across the relay contacts. Just remember that the peak voltage (not rms or AC) of the mains running through the contacts is not more than the rated capacitor voltage value. Do not use polarized capacitors where AC is used. Often a 10nF might make a difference already depending on your back e.m.f of the load obviously. It will also reduce some EMI (electromagnetic interference)

Even if your DC control signal may only see resistance of the coil at the time the coil is on or off. A coil that has inductance and store magnetic energy, the same as any coil will also produce back e.m.f when potential is removed. The collapse of the magnetic field cause a high potential difference, possibly thousands of volts at high frequency. The frequency may in fact be so high that regular diodes or transistors might not stop it. One would recommend a series resistor and use the collector of a NPN transistor with it's emitter to the ground to switch the relay on or off via the base, be sure to have a base resistor to protect the source of the control signal as well as the B-E junction of the transistor, calculation as follow:

Rs = collector series resistor

Rb = is base series resister

beta = current gain for the transistor

Vsource = the control signal voltage minimum that will turn relay on or off

By applying ohm's law we get:

Rc = [Rrelay x (VCC-Vrelay -Vce)]/(Vrelay )

Rb = (Vsource-Vbe)/[(Vrelay/(Relay x Beta)) x 10]

{use factor 10 to compensate for error in beta values}

Don't ever be to comfortable with the fact that there are no electrical connection between the contacts and the coil of a relay. Do not think relays are safe to use with computers or related micro controller devices because they are electrically isolated. It will be a bad mistake!! There are back e.m.f. from the coil aswell as e.m.i from contacts what is induced back into the coil when it has high impedance across it.

It's then recommended to have a fast recovery diode in reverse bias condition across the coil to prevent back e.m.f. of finding its way back home.

This is recommended to protect the driving signal source. Often in small relays using HC or TTL family logic to drive it via a transistor to a transorb or fast recovery diode across the coil may be good enough. Especially if you use it for your self and not to design a heart-lung machine for a hospital.

But if you have micro controllers, computer ports. The damage of a strong back e.m.f may be more than what you bargain for and will probably happen at the worst time in the wrong place. The best is to use a opto-coupler.

The control source will via a series resistor, let say about (330R for a 5V signal) switch an internal LED inside the opto-coupler device on. The light will drive a photo-transistor into forward bias condition. That can be used to drive the transistor that will energize the relay. Since there is no electrical connection between the output pin of the microcontroller that produce the control signal and the relay coil. There is only a one way communication via a light beam. This is by far safer. It creates a typical, 2500V isolation between the robust electrical circuit and it's e.m.f 's, and the sensitive and delicate micro controller or computer circuit environment. A dip in Vcc or pin for less than a millionth of a second dipping with 2 volt or spiking can cause freezing, erratic response or failure of the micro controller. For good electronic design opto-couplers are a very important part of a reliable control system that use micro controllers to control relay output with.

When you disconnect the voltage, the electromagnetic field inside the inductor collapses and all the energy it stored is released to the circuit in the form of another large pulse, but this time with opposite polarity.

Remember:

Inductors oppose changes in current and they store energy in an electromagnetic field.

Capacitor oppose changes in voltage and they store energy in an electrostatic field.

Yes, Kirchhoff law is applicable to linear circuits. In fact, both of Kirchhoff's

laws are applicable to ALL circuits, because they're just conservation laws.

Dodge voltage regulators are located on the firewall. It is the one with 3 wires.