Basic Electricity Primer - Adrian Angel

8/18/2019 Basic Electricity Primer - Adrian Angel

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In this booklet we will be discussing this circuit

The three little circles with arrows in them are transistors. Do you see the little boxes underneath them called crystals?

Do you see the squiggly boxes above them and to the right with little arrows labelled 22,100 Hz, 22,300 Hz, 22,800 Hzcalled tuned filters? To the far left you will see “microphone” and to the far right you will see “antenna.” This is the

circuit of a transmitter.

But first we will start with the basics of electron flow.

Series and Parallel Circuits

In the Olden days, during Christmas when a bulb blew on your string of Christmas lights,

the whole string would go out and you had to take a spare bulb and screw it into every

socket to see where the bad bulb was. It was because the bulbs were hitched together in

series. One bad bulb made the whole string go out. It was fun to see Dad sitting on theliving room floor screwing in light bulbs to try to find which bulb had gone bad. An

analogy would be like a water hose where you put in a kink. The kink would prevent

water from coming out of the end. Imagine if all the lights in your bedroom were hitched

together in series. A blown bulb in your desk in your bedroom would prevent everything

electrical in your bedroom from working.

But nowadays things are hitched together in parallel so that everything gets its own circuit.

A blown bulb, whether in a string of Xmas lights or a blown bulb in a desk lamp in your

room won’t stop all the other bulbs from working. Eventually, though, all the parallelcircuits come together into one line and if there is a fuse (circuit breaker) in that line that

blows, none of those parallel circuits will work. Because that fuse is in series. And the

kink in the hose is there at the blown fuse, so, no water. So you go to the fuse box and


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look for what room is connected to what fuse or circuit breaker. How did the fuse or CB

blow? That room dragged too much current. Maybe you had plugged in five electrical

devices into one outlet in the wall. There was the desk lamp and the aquarium light and

the electric guitar and the hair dryer and the TV and the cell phone charger… Tons of

current went rushing into that room and the wires in the wall began to get hot and before

the wires melted or caught fire in the wall of your house your fuse burned up instead. Or

CB tripped. To keep you from burning down your house.

Other situations can cause massive current flow besides plugging all your Xmas presents

into the wall at one time. Imagine in the bathroom if your electric shaver falls into the sink

full of water. Water is a great conductor of electricity and so is the metal plumbing under

the sink. People were putting their hand into the water and getting electrocuted.

Sometimes the fuse (CB) blew in time and sometimes it didn’t. So the GFCI was created.

Ground Fault Circuit Interrupter. This is a CB that is so sensitive, it will blow if you just

say boo to it. It will trip before you ever get a chance to get shocked. These outlets are

present wherever water is present in your home…bathroom, kitchen, and the outlets

outside on the porch. I was working at a construction site and the licensed electrician was

muttering how come none of the outlets in the bathroom or kitchen were working so I told

him about the GFCI switch in the garage. It was possible that some rain got into an outlet

outside on the porch. Or perhaps water splashed up from the sink and went into a GFCI

outlet. Or perhaps the GFCI was surprised by the amount of current that you hair dryer

pulled… and so the entire GFCI circuit in the home was blown. So he goes into the garagewhere the switch is on the wall, flips it and suddenly all the outlets in the bathroom and

kitchen begin to work.


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Let’s go back to a description of current. If your wire is thick and heavy, like the wire to

your window air conditioner, it will be able to handle the great current needs of your air

conditioner. But if you decide to use a skinny extension wire, that skinny wire is likely to

overheat. The air conditioner is sucking tons of current and the resistance is too much in

the skinny extension wire. Which is two parts of Ohm’s Law: V=IR where I is current and

R is resistance. Resistance is friction and if the resistance goes up, then the heat goes up. A

skinny wire can get so hot that it will melt. We call this a fuse. If a fuse in your car blows,some bright boys will get some tinfoil from their cigarette packs and use it to jump across

the leads. See the outlets in your wall? There are three holes for each plug. The top left

hole is the Return line and is usually connected to a white wire. The smaller top right hole

is the Hot line, usually connected to a black or red wire. It is smaller to keep your fat

fingers from shoving into it and getting electrocuted. The small hole underneath is the

ground line, usually connected to a green wire or a bare copper wire. Let’s go back to the

electricity of cars.

Cars have two electrical circuits. The cranking circuit and the running circuit. Thecranking circuit is when you get into your car, put your key into the ignition, and turn the

key as far as it will go. Your whole car shakes as the battery now sends juice to the starter

motor. Mr. starter motor is a powerful little bugger and a gear in it moves forward to grasp

hold of the crank shaft to turn the engine over. In cranking or turning the engine over,

(same thing) two things happen: the pistons attached to the crank shaft go up and down to

suck in gasoline. The second thing that happens is that the coil sends juice to your

distributor which sends it to the spark plugs. The spark plugs fire which ignites the

gasoline. The gasoline explodes in one of four cylinders and that piston is pushed down to

continue to turn the crankshaft. You feel this and you let go of the key to let it fall backinto the running circuit. Sparks continue to come to the other cylinders, causing

explosions. Your car is now running by itself.

Some unfortunates, sitting in a running car have thought that their car was not running and

they have turned the key to the cranking position. They hear a horrible grinding noise and

realize their mistake. Their engine was already running but they moved the key to where

the starter motor moves forward to engage the engine and of course it is going to move at

a different speed. Worn gear teeth on the starter motor are the result.

There is an auto joke where a lady calls a mechanic and says that her car is not working.

He wants to isolate the problem as to whether it is the battery and starter motor circuit or

the spark plug, coil, distributor circuit. So he asks her: Is your car at least turning over?

She replies, It will, if I push it over a cliff.

Transistors

Are little metal cans with three legs. There are power transistors that can greatly amplify a

signal. You will see these as the final components of a transmitter, just before an antenna,

to amplify a signal before the antenna beams it out into space. Then there are mixingtransistors, that will take two incoming signals and produce four outgoing signals.

Suppose the two incoming are 3 Hertz and 4 Hertz. The four outgoing will be the two

original, the third will be the addition of the two and the fourth will be the subtraction of


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the two. So the four signals coming out will be 3, 4, 7 and One. Why would we want to

do this? So that the Beach boys, whose music ranges from 60 Hertz to 22,000 Hertz can be

beamed around the planet by microwave tower. Of the four signals coming out of the

transistor, We can pick the highest frequency by using a filter. Get a bunch of transistors

with filters and a frequency of 300 Hertz could be bumped up to microwave frequencies

before it exits the antenna. How do sounds travel in electrical circuits anyway?

Microphones and speakers have carbon granules. You talk at or sing at some carbongranules and they will vibrate at certain frequencies. At the end of the line, at the speakers,

the wires vibrate the carbon granules to produce sound and the sound comes out of your

speakers. Now, you may be asking, if a weak, low frequency signal can be upped to a

powerful and high frequency signal using a transmitter, can one go in reverse, taking a

powerful and high frequency signal and reducing it into a weak and low frequency signal?

Yes, that is what a radio receiver does. But unfortunately, a receiver needs a little more

circuitry. Because of all the noise coming in, a receiver needs an extra Detector circuit to

clean up the incoming signal. There was an amusing movie called In Like Flint, a parody

of spy flicks. The good guys find a bug in a pen on a desk and decide to rewire it to make

it to receive instead of transmit so that they can hear what the bad guys are saying. Not

without the added Detector circuit will that work.

The Intersection of DC and AC

Sure, AC comes out of the wall, but most devices do not run on AC. They run on DC. So

why then, does AC come out of the wall? Because it is cheaper. Mr. Westinghouse had a

battle with Mr. Edison in the 19th century. Thomas Edison favored the safer but more

expensive DC as a source of power. He lost. But if your device has batteries, it runs onDC. The more primitive devices in your home, such as those that spin or heat up or light

up (washer, dryer, oven, desk lamp) only need AC. Cell phones, televisions, computers

run on DC. Say you plug your television into the wall outlet. The AC goes immediately to

the power supply. There a small piece of AC is picked off to light up a little bulb that

indicates that your TV is on. There will also be a fuse there to protect your machine

because the AC from Virginia Edison or Conn Ed or Vepco is not constant and it spikes

and really spikes if the power line is struck by a lightning bolt. Past that and there is a

circuit that converts the AC into DC. All the transistors in your machine run on DC. Here

we see an NPN transistor being powered by DC. If the transistor does not get its DC, it

will not take the Beach Boys AC signal coming in and make it more powerful or it may

not mix it up to increase it into a microwave frequency or decrease it so that you can hear

it on your 60 to 22,000 Hertz speakers. The capacitors, represented by two little parallel

lines, permit AC to cross them but block all DC, isolating each transistor from each other.


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In Diagram A, you see three transistors. Each has its own crystal. And each has its ownfilter. The DC voltage powering each transistor is separate because they are isolated from

each other by capacitors. But the capacitors will let AC signals cross them… so that the

AC can get to each transistor and to go from the microphone on the far left to the antenna


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on the far right. Suppose a Beach Boy sings into the microphone on the left. His voice

range and guitar would be from 60 Hertz to 22,000 Hertz. Then imagine that the crystal

selected beneath transistor Number One vibrated at 100 Hertz. A signal as high as 22,100

Hertz would come out of the transistor. And imagine that the tuned filter was tuned for

22,100 Hertz. Then only the 22,100 Hertz signal would get by, cross over the capacitor to

transistor Number Two. Imagine that the crystal under transistor Number Two vibrated at

200 Hertz. It would add to the 22,100 Hertz signal and come out of Transistor Numbertwo at 22,300 Hertz. It would cross over if the filter was tuned for 22,300 Hertz. Then the

signal crosses over the capacitor to enter transistor Number Three. Imagine that the crystal

under this transistor vibrates at 500 Hertz. It adds to the incoming signal of 22,300 Hertz

and a signal as high as 22,800 Hertz comes out. The tuned tank, if tuned to 22,800 Hertz

would let this signal by to continue on to the antenna, eventually. On the way to the

antenna the signal would enter Power transistors designed to boost the signal. These

Power transistors are big metal cans and when I worked in a CB shop, the truckers wanted

these for their CB radios. Thing is, they often would be so powerful that when the trucker

keyed up his radio at the truck stop, it would blow out the nearby CB radios in the rigs

parked next to his rig.

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Basic Electricity Primer - Adrian Angel