Electronics 101

I hope to shine some light on the various electronic components found in the devices we use daily.
This is by no means a complete explanation, there are books about electronic basics if anyone is intersted to expand their knowledge.

To keep this understandable, I will stick to DC circuits. Formulas are easier to handle, behaviour of components is “obvious” and you can trace the flow of electrons with your finger.


There are two major groups of components:

Passive Components

Passive components are all the ones that “just do their thing”. Such components include:

  • Resistors
  • Potentiometers and Trimmers
  • Capacitors
  • Coils and Inductors
  • Transformers
  • Oscillators and Crystalls

Active Components

Active components are all the ones that “influence” circuit behaviour by switching of some kind.

  • Diodes, Rectifiers,
  • LEDs, Photodiodes
  • Optocouplers
  • Transistors, FETs, Triacs
  • Piezo elements
  • Tubes (Valves)
  • ICs (= Integrated Circuits)

Important Units

  • Volt - Named after Alessandro Volta, this SI-Unit describes the electric potential. Think of Volt as a Lake on a Hill. The higher the Hill, the higher the energy the Water can release.
    Volt V is commonly symbolized by U in formulas.

  • Ampere - Also named after a scientist (André-Marie Ampère), this SI-Unit describes the flow of electrons. Think of this as the mass of water in a river.
    Ampere A in formulas is writen as I

  • Watt - Named after James Watt, this SI-Unit describes power. It is the product of Current times Voltage. Wattage W in formulas is writen as P

  • Ohm - Named after Georg Simon Ohm, is the SI-Unit of electrical resistance. Resistance Ω is writen as R in formulas


Other important Names&Acronyms

  • Ground (= GND) - The 0 point of the circuit.

  • Power (sometimes: Rail or V+/V-) - Source of power. Can be positive or negative in respect to GND.

  • Source - Signal source, external input to the circuit.

  • SMD - Surface Mount Device, these components that are soldered to the top of a circuit board. As opposed to through hole components which have “legs” that stick through the PCB

  • PCB - Printed Circuit Board (sometimes PC-Board), the card holding components in place and connecting them. Simple PCBs have 1 layer, the most complex ones as of 2020 have 9.



With the fundamentals covered, lets have an indepth look at the various

Components


**Resistors** Resistors are probably the most basic component. They resist the flow of current causing a voltage drop over them.

These guys come in any shapes and sizes (and power ratings), from smaller than a grain of rice to heavy water cooled variants.
In a schematic these can be represented by one of two symbols (the box is the new IEC symbol):
image

In the wild, you typically find resistors in these shapes:
image
Source

A special type of resistor are Potentiometers (= Pot) and Trimmers. These are variable resistors.
A potentiometer is between Source and Ground providing a reference in respect to the two. While technically the same, Trimmers are not rated to frequent adjustment.

image

Note: “This Resistor is green!” → Could be an inductor. More on those further below.


Capacitors
These components resist a change in Voltage, meaning raising or lowering it will be delayed.
If you think of electricity like water, a capacitor is like a tank, the larger the surface, the more water you can drain before a level change.

It is important to note that not all capacitors are okay with reverse polarity. Any polarised capacitor hooked in reverse or to AC is a potential fire hazard on top of releasing toxic gases.

Difference between Capacitors and Batteries:
Capacitors store electricity as an electric charge, Batteries store it as chemical energy.

The Symbols and their respective Parts:
image
Source


Inductors
Similar to how capacitors resist a change in voltage, Inductors and other coils resist a change in Current.
In the water model, this would be like water moving (or not moving) through a pipe. Just like slamming the water tap shut will cause a water hammer, or a voltage spike (= current still going = raise in voltage) in an inductor.

In a schematic, an inductor will look like one of these (mostly ignoring the core material, two lines means core :stuck_out_tongue: ):
image

In the wild:
image

A special type of inductor is the Common Mode Choke. These take advantage of current flowing in and out of an area causing magnetic fields that cancel each other posing very low resistance to DC. Noise arriving on both lines causes opposing magnetic fields that then block the noise from entering (or leaving) a section.

Working principle:

Symbol:
en-20140724-p1_img0012

In the wild:
image


Transformers
When you put a second (or third, or even more) coils into an inductor, you get a Transformer.
The ratio of windings on either side results in different voltages. Transformers ONLY work with AC.

There are many ways to build these, depending on application. A few types:

  • Isolation Transformer - 1:1 Ratio isolates the two sides electrically

  • Auto-Transformer - Variable Ratio, allowes dynamically adjusting the voltage of the output side

  • Center-Tapped, Generates multiple voltage levels. Often found in audio gear because Op-Amps often like running of -12 and +12 in respect to Gnd.

Symbols:
image

Center-Tapped:
image

Auto-Transformer:
image

In the wild:
image


Oscillators and Crystals

When supplied with a voltage, these things oscillate with a specified frequency. Useful when the integrated timer in an IC is not precise enough for time keeping or synchronizing.
These things are available in nearly any frequency one could desire. In combination with a counter, even the impossible frequencies can be achieved :wink: .

Symbol:
image

In the wild:
image
Source



Diodes
A “normal” Diode is an electronic check valve. It only allowes current to flow in one direction and blocks it in reverse. The cost of this is a small voltage drop due to the semi-conductor inside (usually 0.8V).

Schottky-Diodes perform the same function, have a faster response time and lower voltage drop. Slightly increased price tag for the service.

Zener-Diodes allow current to pass in reverse when a certain voltage threshold is reached.

Tunnel-Diodes are highly specialized and I have no idea what uses for these things are.

Photo Diodes generate current depending on the light hitting them.

LEDs - Light Emitting Diodes do exactly what the name implies. Reverse polarity, high currents and over-temperature should be avoided to prevent damage.
OLEDs are similar (O for organic), I have never worked with these.

Laser Diode - Emits laser light (= single frequency light) usually from a crystal when current passes through them.

Symbols:
image

In the wild:
image
Source


Transistors
By applying a voltage to the Base, current can flow from the Collector to the Emitter. In simple words: An electrically operated switch.
These things can switch way quicker than any mechanical switch ever could (8 GHz anyone?) and the lack of mechanical contacts allowes for near infinite switching cycles.

Symbol:
image

In the wild:


Source

Similar to Transistors are Triacs. These perform the same task as transistors, except they can switch AC.

FETs are a type of Transistor, the most well known arguable being MOSFETs.


Optocouplers:
When you combine an LED and a Photo Diode (or Photo Transistor) into one unit, you get an Opto-Coupler. These little chips allow to monitor the state of the other side without having an electrical connection.
image


Tubes
Exist in many different sizes, for switching, rectification or amplification tasks. Basically the father of modern semi-conductors.
The basic working principle is that the heating element generates an electron cloud wich will then flow towards the positive end. The vaccuum is needed to allow for a free flow of those electrons.

Adding what is called grid enables control of the electroon flow making the tube a switch.


ICs (Integrated Circuits)

This is where the fun begins!
Imagine having a complete circuit, but instead of it being the size of a toaster, it is a small 14-pin chip.
The “legs” (= pins) are connected to the circuit inside the plastic (or ceramic or metal) packaging.

You can find functions from power monitoring, battery management, amplification, storage, and many more as ICs. So consult spec sheets before randomly ordering a collection of theses :wink:

The most common type of IC arround an audio forum is probably an Op-Amp in an 8-pin DIP package. To make matters a little more complicated, there are dual and single Op-Amps in these packages.
The notch marks the pin 1-8 end.
image
image


And with this, you now have an overview of all the basic parts that make up electronic circuits. My next post will include some basic formulas and circuit drawings to show these parts in actions.

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Very cool post. I have a basic understanding of all this but hopefully you’ll teach me a bunch :love_you_gesture:

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So when my equipment breaks which one of these little doohickeys do I need to replace? :smirk:

The broken one :stuck_out_tongue:

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Way back in a previous life I used to do board and component level repairs on cell phones. I was component level certified on NEC, Motorola and Oki cell phones, board level for everything else.

Not that I knew what I was doing but I could follow directions and troubleshoot appropriately. But the MOST IMPORTANT thing with all this crap is having the proper tools and test equipment. Otherwise you might as well be using a hammer to try and repair crap.

I still dream about the PACE workstation I had access to, you could easily make mm sized welds and hot air remove smd chips etc. I miss that beautiful hunk of aluminum with the red led numbers. :heart:

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Should we be expecting Maze Frame Electronics MasterClass ads on YouTube now?

I am a hobby tinkerer, not an electronics engineer. :rofl:

Part 2

Components in Circuit

Warning: Voltages above 30V are dangerous.
(With enough effort, a sweaty teashirt and car battery can kill, different story :wink: )


Important tools
When working with or near electronics, there are some important and some nice to have tools.

  • Multimeter - Resistance, Voltage, Current, sometimes Capacitance and Temperature measurement device in one. Way better than one of those glowing screw drivers at determining if a circuit is live (as in: Can make you dead).

  • Size 1 Philips Head - Gets you into most devices, like your multimeter when you blew a fuse because you set it to mA when dealing with A.
    Insulated ones are nice, sometimes don’t get into tight spots. Only take stuff apart that is unplugged!

  • Replacement Fuses for your Multimeter - No shame in taking the thing apart to replace a blown fuse. Never buy just one! And avoid the glass tube ones. Under extreme fault conditions (= shit hitting the fan), the wire evaporates coating the glas making it conductive causing a minor explosion.

  • Soldering Iron - No need to own a Weller Rework Station when you solder two cables back into their plugs a year. Workable soldering irons can be had for 20 bucks.
    I saw people do this: The shiny end gets HOT! Do Not Touch That!

Optional Tools

  • Known Working USB charger - When troubleshooting a phone not charging, having a known good USB charger (and cable) on hand helps a ton. Can also use your multimeter to determine if the wall socket has power.

  • Flashlight - For that extra bit of light

  • Magnifying glass & Inspection mirror - For small and tight spots

  • Grounding wrist strap - For ease of mind when dealing with expensive electronics. In Europe, most sockets have a grounding pin or grounding springs to clamp to. Alternatively a water tap or plugged in computer (not a notebook) also work as grounding points.


Toaster Timer

While you could use a bimetal strip and screw to do heat-based timing or a microcontroller there is also a super simple analog circuit to achieve the same.

Note: Do not implement this 1:1 as I “just winged” this circuit from what I remember building.

Operating principle:
The 5V supply charges the Capacitor C1 via the Variable Resistor R1, when C1 reaches 4V, the Zener-Diode U1 allowes the Transistor Q1 to pass current through the LED.
R2 and R3 are to protect the Transistor or LED against too high currents.
The reset switch discharges the capacitor reseting the timer.


Blinking Lights

Very common circuit is to have two LEDs blinking. Running of a 9V battery and built from 10 components, it just blinks back and forth.

Operating Principle:
The capacitor C1 controlls the state of Transistor TR2 and vice versa. A Transistor turning on means it discharges its Capacitor turning the “opposing” Transistor off.
In other words: This is an astable multi vibrator, no state is stable and it has multiple states.

Circuit design and build guide source


Ohms Law
Ohms law is simple: Resistance = Voltage / Current
This simple formula by applying simple maths can be made into two variations:

  • Voltage = Current * Resistance
  • Current = Voltage / Resistance

You may ask why this is such a big deal.
Picture this: Your multimeter does only measure current and voltage. How do you determine the resistance of your headphones?
Take a AA (or AAA) battery (which can be yanked from a flashlight or remote), measure its voltage and write it down.

Now touch the tip of your headphone jack to the battery, then use the test leads of your multimeter to complete the circuit in current mode.

You end up with a voltage (about 1.3V) and a current (anything from about 0.3A down to 0.002A). And just like that, you know the resistance of your headphones!


Basic Soldering Guide

  1. Clean workplace, preferably a piece of wood to protect the table (or carpet)
  2. Clean Tip = Good Tip - Don’t use your soldering iron to shrink heatshrink, please!
  3. Flux is your friend. That small puff of smoke when touching the solder to the iron is what makes the joint work. You can also dunk blank cable ends into flux or use a syringe to apply some to the PCB you are working on.
  4. Heat the parts you want to solder, then touch the solder to the joint.
  5. Let the joint cool on its own. No blowing on it or drenching it in the sink.

Is my solder job good?
What does your multimeter say?
Resistances greater than 0.1 Ohm (idealy 0 Ohm) are reason for concern.

How does it look?
It should be a clean shiny surface surrounding the wire or pin comletly without being a massive ball of metal.

image


image

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FYI on the soldering, above 400 MHz good solder joints are even harder and look closest to the middle OK solder joint (with the rare through hole). Why? Parasitic values start messing with circuits. The #1 way to cut down a parasitic inductance is keep all your via and solder joints as SMALL as possible.

Keep it up @MazeFrame!

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This post here is mainly to bump this thread up a bit. Also shows you what lightning does to your electronics:

Next regular post in this here will be Multimeter, Measuring basics and Safety

Part 3

Multimeter basics

:warning: Warning: Voltages above 30V are dangerous.

Introduction
A good multimeter does not have to cost a fortune. If you need one twice a year, don’t shell out $200.
I would recommend to buy one with detachable leads so you can hook up the right probe for the right job.

Most cheap multimeters have 3 settings:

  • Voltage
  • Current
  • Resistance (included Continuity)

Other functions you may find:
  • Diode Test
  • Capacitance (hit & miss in my experience)
  • Inductance (Multimeter ≠ Inductance meter, very different devices)
  • Temperature (using a thermocouple, often with an adapter)
  • Frequency Counter (hit & miss in my experience)
  • Transistor tester (what for? Don’t you have a datasheet?)

  • Max/Min Function
  • Hold (Flukes Auto-Hold is :100:)
  • Backlight
  • Range Adjust

Measureing

Range selection
When your meter does not do this automatically, you select the range that includes the highest value you expect.
Note that when measureing current, the inrush current may be a lot higher than current while the load is running.

To throw all beginners into the deep end, welcome to the bastard meter from hell:

90V is the outer one.
20V is the center scale.
For 10A, you have to take the same scale as 20V, but divide by 2. And the 1A scale is the inner one, divided by 10. Don’t laugh, I have seen this in the wild!

The only good feature of this example piece is the fact it requires you to plug the probes from Black&Blue for volts to Green&Black for Amps.
There are meters that shutter the incorrect ports so you don’t blow up fuses (Gossen Metrawatt does this on a lot of their meters).

Do yourself a favour, buy a good meter.

Probing
Do get good results, you need good contact. The manual probes will often be “good enough” for resistances or finding if there is voltage presend. For everything beyond that, you want alligator clamps, screw terminals, 4mm hookups, etc.
That way your fingers (and body) don’t skew the results or put your heart and lungs into the line of fire.

:warning: When Probing arround >30V, use shielded test leads like the ones below. Only use 1 hand to hold the probes, the other hand holds the meter.


↑ Honestly though, use clamps/plugs to hook up and don’t even touch whatever you measure.


Correct Meter Positioning

Current (A) - Your meter will be in series with the load. In this example, a light bulb.
image
This is also how you measure resistance, capacitance, etc. Just without the battey in circuit.

Voltage (V) - Your meter will be in parallel with the load.
image

:exclamation: Urgent Advice: After EVERY use, plug the leads back to measure volts.
That way you will not blow up your meter or the fuses inside it by accident.



Purchase advice

You want a True-RMS (= TRMS) meter, simply because these types of meter can measure AC.

The measurement leads should have guards so your fingers don’t slip into the danger zone.
Fluke TL 75 for example:
image

Analogue vs Digital
I find analog meters to be way too much hassle. The neelde is never readable, accuracy is at the mercy of correctly positioning the meter and there are multiple scales of which you have to read the right one.
Buy a digital meter and you are set, even when holding the meter at wierd angles.


Autorange vs Manual
Do you want to think about the highest value you could see?
Do you want to step through the ranges until you get a usefull measurement?
Are you mad?

Answered any of the above questions with yes, then get a Manual one. All the normal people, save yourself the hassle and get an auto-ranging one.


Brands that won’t blow up in your face:



Misc Advice

Help! My meter does not measure amps!
→ Have you checked you got the test leads plugged in correctly?
→ Correct range selected?
→ Still nope? You blew a fuse. Time to open the battery cover (or the entire meter) and replace it

Fuses
You want ceramic fuses in all your devices, especially the multimeter you have in your hand.

The good ones are filled with a fine sand that will take up the metal vapour under extreme fault conditions interrupting the current flow. Glas fuses may cover their insides in metal, which will then conduct making them explode.
Video showcasing fuses under fault conditions

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Anyone interested in nearly 25 Minutes of electronics nerdery?

1 Like