Kila, the Magic Husky's Ham Radio College featuring Kila and her Trusty Sidekick, Ben

Kila, the Magic Husky's Ham Radio College

featuring Kila and her Trusty Sidekick, Ben

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Episode 5 -- aired on March 14, 2016 -- Schematic Diagrams and Resistors, Capacitors and Inductors and more about Alternating Current

Listen to the episode 53.7 MB MP3

Reading Electronic Schematics

The Technician Class License Exam Question Pool includes a dozen questions related to drawing and reading schematic diagrams.
A Schematic is a picture of where electricity flows in a circuit. Various power sources, loads and electric components are represented by particular scribbles connected by lines, representing wires in a drawing.
By convention, all lines connecting elements on a schematic are drawn straight and only vertically or horizontally, with L shapped bends, as needed.
Whenever on a schematic, two lines cross, they either represent wires which connect with one another, or wires whch DO NOT connect. If the wires are supposed to connect, a filled in circle is put at the intersection of the lines. If the wires do not connect, either no filled-in circle is drawn or, less ambiguously, one of the lines, as it intersects the other, is replaced with a 180 degree arc or open half-circle to denote a "hop" over the other wire so as to show them not connecting, such as you can see in this schematic of a simple audio amplifier:
Oftentimes, since a large circuit will have many different components connected across the DC Power Supply's (-) and (+) connections, we often will represent the positive DC voltage, or "Signal Input" as nothing more than a tiny open circle, such as the pair of them on the left side in figure T1.
Very often, in AC or DC circuits, the chassis of the equipment will be connected to (or considered to be) "Ground". That is, the word, "Ground" here refers to a convention that the minus DC voltage is connected to so many different parts of the schematic, that rather than connect them all together with lines on the page, we just use the symbol shown in T1 (5) to imply that all those connections are connected together with the minus power supply and probably also the chassis of the equipment. This is to prevent static electricity from interacting with the circuit.
The schematic above also shows both ground as well as +12v and -12v. What is happening here is that the power supply has two different 12 volt DC sources of power available to this circuit. The plus of one of them is connected to ground and the minus of the other is, also.
The Ground symbol in this schematic is different than the one in the other three examples, T1 through T3. This is actually a ground symbol, the one labelled chassis ground in T1, T2 and T3 is also a ground but more modern; it referrs to the metal case in which the circuit is housed. The symbol in this schematic below R5, at one side of the Audio In, below R7 and K1 (which is a speaker, a device for converting low level AC electricity into sound that you can hear) is a ground symbol more widely used and, in the old days, meant an actual metal rod 8 feet long, stuck into the actual dirt outside, with a wire coming into the house. We often connect circiuts (especially those of transmitters and receivers connected to big tall antennas outside) to ground so that the kinds of stray static electricity that cause lightning won't hurt our equipment. They exist all the time, in small enough amounts to ruin expensive radios but not large enough to actually cause lightning you can see outside.
- Figure T1 -- A battery charger
- The items below outlined in Bold represent symbols which appear in the Technician Class Exam Question Pool. That is, if you learn to recognize all the symbols in bold, that represents another 12 questions in the pool of 470 to which you have the answer.
  1. Resistor
  2. NPN Transistor
    - NPN = "Never Points iN"
    - PNP = "Proudly iN Pounts"
  3. Incandescent Light
  4. Battery
  5. Chassis Ground
- Figure T2 -- DC Power Supply
  1. Power Plug
  2. Fuse
  3. Single-pole single-throw Switch
  4. Transformer
  5. Diode
  6. Capacitor
  7. Resistor
  8. Light Emitting Diode (LED)
  9. Potentiometer or Variable Resistor
  10. Zener Diode
- Figure T3 -- Output circuit of a transmitter
  1. Input to this stage of the circuit
  2. Variable Capacitor
  3. Variable Inductor
  4. Antenna
Resources

What's up with Sine waves?

A Sine Wave is the line which is produced by taking the points around a circle, beginning at the 3-oclock position, and plotting them on a number line as they are measured away from the x-axis. For completeness, a Cosine wave looks exactly like a sine wave, but instead of starting at zero, it starts at the top and makes the same wave but is plotted from the points on the circumfrance of the circle as measured by their distance away from the y-axis instead.
A Sine Wave as I've mentioned several times, is pretty magical. First, it represents the actual values of the points along the perimeter (or circumfrance) of a circle. Second, and most importantly for us, any arbitarily complex waveform can be shown theoratecally to be constructed from the conbination of an arbitrarily large number of specific sine waves at different frequencies. I realize that to mathematically prove that to you will require more math than I myself posess, but you should just take my word for it, because...
Due to the fact that any waveform can be mathematically shown to be constructed by mixing the wave forms of an arbitrarily large number of different sine waves, you can mix two wavesforms to make 4:
- The two original waveforms and
- The two added together and, interestingly,...
- The difference between them.
This will be shown later to be extremely valuable for making radio receivers and transmitters at arbitrarily high frequencies.
Furthermore, a sine wave is the only kind of signal which DOES NOT make harmonics. A Harmonic is the same signal, much much quieter, but at twice the frequency, three times, four times, etc. All radio transmitters which send a signal other than a sine wave produce harmonics. Therefore, All radio transmitters are designed with specific filters built into them to prevent harmonics from getting through to the antenna. This kind of filtering is performed using various techniques, beginning with the kind of filtering performed by tuned circuits which are composed of Inductors and Capacitors.

Inductors and Capacitors (7 questions)

Capacitors - It is possible to build up and hold an electrical charge in an electrostatic field. This phenomenon is called capacitance, and the devices that exhibit capacitance are called capacitors. A capacitor is simply two conductive Surfaces, Separated by an Insulator. If you put one across a battery, it'll fill up with a charge. If you remove the battery, the charge will sit there for a while. A capacitor is therefore kind of like a very short term battery. If you replace the battery with just a wire, the capacitor will discharge. It takes time to charge and time to discharge.
Variable Capacitors
Resistance and Capacitance
"The product of R in ohms times C in farads is called the time constant (also called the RC time constant) of the circuit and is the time in seconds required to charge the capacitor to 63.2% of the applied voltage. (The lower-case Greek letter tau, Τ, is often used to represent the time constant in electronics circuits.) After two time constants (t = 2Τ) the capacitor charges another 63.2% of the difference between the capacitor voltage at one time constant and the applied voltage, for a total charge of 86.5%. After three time constants the capacitor reaches 95% of the applied voltage, and so on. [..] After five time constants, a capacitor is considered fully charged, having reached 99.24% of the applied voltage. Theoretically, the charging process is never really finished, but eventually the charging current drops to an immeasurably small value and the voltage is effectively constant." [2016 ARRL Radio Amateur's Handbook, page 27 of chapter 2]
Variacs and Potentiometers
Inductors and Inductance
- Magnetic fields
- Henrys and Millihenrys
Impeadance and Frequency
Reactance and Impeadance X(L) = 2 × π × F × L, where
X(L) is Inductive Reactance, and
π = 3.14, and
F = The Frequency in Hertz and
L = The Inductance in Henrys.

(Yes, since it is a pluralized proper noun, it is correctly spelled Henrys and not Henries; I knew you'd ask).
Resonance, networks and Filters
Tuned Circuits and Resonance
Phase and Eli the Ice man

Tantalum Capacitors and the mining of Conflict Minerals

Tantalum capacitors are electrolytic capacitors whose anode electrode (+) is made of tantalum on which a very thin insulating oxide layer [manufactured rust] is formed, which acts as the dielectric of the capacitor. Tantalum is a hard, transition metal (element number 73). It is highly corrosion-resistant but somewhat hard to find.
Tantalum, always together with the chemically similar niobium, occurs in coltan (a mix of columbite and tantalite).
Since the mid-1980s, tantalum capacitors have exhibited around a ten-fold improvement in CV/g (microFarad-Volts per Gram) values over standard aluminum electrolytic capacitors.
The Congo, more recently renamed, the DRC ("Democratic Republic of Congo") supplies about a fourth of the world's Coltan for Tantalum capacitors. Australia used to be the world's leading source, but production there has been declining. Most Central African coltan is considered conflict mineral because mining areas are controlled by armed factions and organized crime. Even legal mines pay 12 hour per day miners $5 per day. $3 per day is the country's minimum wage for such work. If you're wondering what that looks like, check out the 2006 movie, Blood Diamond starring Leonardo DiCaprio. It isn't pretty.
There is no simple way to keep conflict coltan out of the stream of legitimate minerals used by manufacturers. It doesn’t have "geo-fingerprints" like conflict diamonds.
Rwanda, Uganda, Burundi and their proxy militias are the primary exploiters of coltan in the Congo. In an 18 month period Rwanda made $250 million as a result of exploitation of coltan in the Congo. Although Rwanda and Uganda possess little or no coltan, during the period of the war in the Congo, their exports escalated exponentially. For example, Rwanda's coltan export went from less than 50 tons in 1995 to almost 250 tons in 1998.
In South America, the coltan mining industry is operated by militia groups or by Colombian and Mexican drug cartels. Because these mines are located in national reserves, indigenous people are often forcibly conscripted as miners. For instance, in Colombia, the Puinawai natives say that the coltan operations are "guns, pointed at the earth beneath their sacred mountain." Children are regularly forcibly recruited to work in the coltan mines and are guarded at gunpoint by the militia groups that have forced them into mining.
Coltan, like any metal, is a toxic contaminant. Since it is usually pan-mined, the mining process and slurry from this process contaminates the water supply and is harmful to the entire ecosystem.
Coltan uses include
- Laptop computers
- Cellular phones
- Jet engines
- Rockets
- Cutting tools
- Camera lenses
- X-ray film
- Ink jet printers
- Hearing aids
- Pacemakers
- Airbag protection systems
- Ignition and motor control modules, GPS, ABS systems in automobiles
- Game consoles such as playstation, xbox and nintendo
- Video cameras
- Digital still cameras
- Prosthetic devices for humans; hips, plates in the skull, also mesh to repair bone removed after damage by cancer
- Suture clips
- Corrosion resistant fasteners, screws, nuts, bolts
- High temperature furnace parts.
- High temperature alloys for air and land based turbines

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