Teaching an old dog new tricks.

Thread Starter

RexR35630

Joined Dec 9, 2023
17
Hello Everyone,

My name is Rex and I'm new to AAC.
I am just beginning my learning of electronics. I've been a systems administrator, MCSE, know all about networking, workstations, servers and databases and websites. But I've always wanted to learn about electronics.

I'm not sure if ACC is for beginners. Looking at the forum topics it seems out of my league when I'm just trying to nail down Ohm's law.
I don't want to bother this forums with simplistic questions and beginners concepts, but I am looking for a forum that I can ask my questions regarding electronics. I don't want to ask how do you know which resistor to use to turn on a LED with a 5v source in the"FPGA's" forum when I don't even know what a "Field Programmable Gate Array) is.....YET.

I have many questions regarding online courses, circuit simulators, and just basic beginners questions and I don't want to bother you guys with these things if I need to be on a different forum, or post things in the wrong topic and aggravating everyone.

So if you have any advice for me and wanna spend the time to respond to this post I would greatly appreciate it.
Stickys I need to read? Other sites to check out? Recommend courses on the fundamentals electronics?

Thanks
~Rex

P.S. My wife bought me a Oscilloscope last year for Christmas, I don't know how to use it, it's still in the box. Asking for a Variable Power Supply this year. Maybe I'll get further along this year. LOL, Merry Christmas!
 

dl324

Joined Mar 30, 2015
16,991
Welcome to AAC!

Recommend courses on the fundamentals electronics?
It'll be difficult for you until you build some sort of foundation. Make sure you understand the basics like Ohm's Law because that's the foundation you'll be building on.

Until then, enjoy trying to drink from a fire hose.
Asking for a Variable Power Supply this year.
My first project was a power supply. Except I had an ASEET and, pretty much, knew what I was doing. Still, it's a good first project and you get to use something that you built. Mine was nothing fancy. Dual adjustable outputs, no current limiting, no display (built it in the late 70's when panel meters were still quite expensive).

These days, you can buy a used laptop power supply and add something like an LM317 on the output.

My second was a digital voltmeter using a panel meter that cost me $30.
LOL, I missed this sticky before posting.
I don't see anything wrong with the title. But now you know that more descriptive titles are better.
 

Tonyr1084

Joined Sep 24, 2015
7,948
Welcome to AAC.

We all had a beginning. And Dennis beat me to the welcome.

There are things over my head. Some way over and some that just skim across the top - as you can see from the polished scalp.

Basically it comes down to math. Ohms law basically states that all things are related. A given voltage and a given resistance will have that specific amount of current. DC is the easier part but AC is a bit more advanced. Just give it time and don't be afraid to ask questions.

Breaking that down into something simple; suppose you have a resistor in a circuit and a voltage. The resistor is 100Ω (ohms) and the voltage is 10V (volts). That means that 10V ÷ 100Ω = 0.1A (amps) designated as the letter "I" Those numbers can be turned around and still come out the same. If you have a circuit with an unknown voltage but you know the resistance is 100Ω and you know there is 0.1A then you multiply. 100 x 0.1 = 10. You have 10 volts. Since resistance is the thing that is most often a fixed value (doesn't change) you can change the amperage by changing the voltage. More volts and you'll have more amps. 100V ÷ 100Ω = 1A.
E (volts) is equal to I (amps) times R (ohms) ( ( E = IR ) )

That's the most basic part of a beginning. There's an educational section where you can learn from the very most basic to the very advanced. You can go as far as you like.
 
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BobTPH

Joined Jun 5, 2013
9,130
It sounds like you are hesitant to actually get started. Fear if doing something wrong is likely the cause. The solution is to use only things that can’t do much damage.

Take an old 5V phone charger, snip off the end of a USB charger cable and you have a power supply that will allow you to experiment without danger.

Get some resistors and LEDs, and a solderless breadboard with jumper wires, and we can show you how to apply Ohm’s law to design your first circuit.
 

nsaspook

Joined Aug 27, 2009
13,418
Start here: https://www.allaboutcircuits.com/textbook/
and here: https://maritime.org/doc/neets/mod01.pdf
Navy Electricity and Electronics Training Series Module 1—Introduction to Matter, Energy, and Direct Current

It will be a while before you do electronics as electronics is only one technology within electrical science. First you need to understand basic electrical science with a very open mind so you can forget all of the misinformation or preconceived notions you have about the nature of 'electricity' as a thing instead of a field of study.

http://amasci.com/miscon/whatis2.html#:~:text=Electrical science is the study,Magnetism, and EM wave mechanics.
What is electrical science?
Electrical science is the study of electrical effects... and electrical effects are caused by electric charges and by the electric and magnetic fields associated with charges. Electrical science is divided into sections called Electrodynamics, Electrostatics, Magnetism, and EM wave mechanics.
Electrical science is often called "electricity," which can be confusing. For example, the study of lightning is the study of electrical science, so the study of lightning is the study of "electricity." But this doesn't mean that lightning is "made" of electricity. When we study lightning, we are studying a science topic, and we're not studying a substance called "electricity."

It might be better if electrical science had some other name than "electricity." After all, the study of light is not called light. It's called optics. Nobody thinks that lenses and light bulbs are made out of light, since whenever we study lenses and light bulbs, we study "optics." Optics is obviously a science topic. But plenty of people think that lightning is made out of electricity, since whenever we study lightning, we study a science topic named Electricity, and most people imagine that we're studying a SUBSTANCE named "electricity." which looks like blue-white fire that reaches across the sky.

"Electricity" or Electrical Science is confusing in another way. This science topic is divided into two sections called Electrostatics (the study of charge and voltage), and Electrodynamics (the study of current and changing fields.) Many people have convinced themselves that there are two kinds of electrical energy: static and current. Wrong. In truth, there are two kinds of ELECTRICAL SCIENCE: Electrostatics and electrodynam ics. Since "electrical science" is called "electricity," we can say that the two types of electricity are static and current. What we MEAN is that the two types of electrical science are the study of charge and the study of charge-flow. See what's happening here? A field of science has been mistaken for a type of energy! And the two fields of science, Statics and Dynamics, have been mistaken for two separate KINDS of energy.

How many K-6 textbooks insist that "static electricity" and "current electricity" are the two main forms of energy? This is a weird distortion which probably arose over many years of misunderstanding. What they MEAN is that there are two types of electrical science, one dealing with charge and voltage, and the other dealing with currents and circuits. Two kinds of "electricity," where the word "electricity" means Electrical Science.
It seems sort of pedantic at first but eventually, if you progress into more advanced electronics you will see it's important. SO get it right in the beginning.
 
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dl324

Joined Mar 30, 2015
16,991
Stickys I need to read?
Read the thread on LaTeX for formating equiations.

Some will try to write the euation equation for charging a capacitor as something like:
Vf=Vi(1-e^(-t/RC))

This is much easier to read:
\( \large V_f = V_i(1-e^\frac{-t}{RC}) \)

Also be careful with units and the proper names for things.
I don't want to ask how do you know which resistor to use to turn on a LED with a 5v source
Volts is abbreviated with a capital V (5V).

A pet peeve of mine is people calling MOSFETs (Metal Oxide Semiconductor Field Effect Transistor) FETs. The first available field effect transistors were junction FETs (JFETs), so when I see/hear FET, I think JFET. There are many kinds of field effect transistors (IGFET, MESFET, etc), so FET isn't descriptive.

In general, acronyms are all caps.
 
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Tonyr1084

Joined Sep 24, 2015
7,948
Reading schematics is the key. Understanding what the symbols mean will show you how a circuit works. There are simulator programs you can get - but I'd suggest you first get the basics down before you try your hand at sim's.

The most basic circuit is lighting an LED. A simple 5mm LED that operates on 5 to 20 milliamps is an easy enough place to start. You need a voltage source, a resistor and an LED. But you need to understand what the max and recommended amperages are for the LED you're using. Not all LED's operate the same. That's a little deeper.

Suppose you have a 12 volt battery and an LED that you want to power it with 10mA (milliamps). Diodes, LED's and other components have a forward voltage that comes into play. The below circuit shows the LED as having a 2Vf. That Vf must come into the calculations. ( 12V - 2Vf ) ÷ 10mA = 1KΩ. Different LED's will have different Vf's, so you must know what that is. That information usually comes from a Data Sheet. But not all LED's come with a data sheet, which can make it tricky. Let's leave that for another day. For now the circuit below shows 10mA flowing through the circuit. The LED is lit and it is not burning out because you're not exceeding its maximum amperage rating. Again, that comes from a data sheet.

Not to get bogged down, reading a schematic will take some time. But when you learn it will become like reading sheet music to a musician. The afore mentioned circuit looks like this:
1702148611487.png
Anywhere you measure the current it will always be the same throughout the whole circuit. BUT WAIT! There's more to it. The battery has its own internal resistance. In most cases that will not be critical. You can expect the above circuit to behave as is shown.

Look at the schematic. It tells the story. Even without the 10mA designations inside it - the story should be clear. 12V, 1KΩ, 2Vf. You can calculate the amperage from there and come up with 10mA. If you want or need to know the wattage (important for selecting an appropriately rated resistor) multiply the voltage times the amperage. 12V x 0.01A = 0.12W (or 120 milliWatts). A 1/8W resistor can handle the job but it will get hot. A 1/4W resistor will also handle the job and it will not get as hot because it's rated for 250mA, whereas the 1/8W is rated for 125mW.

Don't let this scare you. It may seem like a lot but it's really among the most basic of circuits, and you'll get to a place where you look at this and intuitively know it's running at 10mA and 125mW.
 

dl324

Joined Mar 30, 2015
16,991
Also, learn how to draw readable schematics. The preferred flow is left to right and top to bottom. Avoid scenic routing, unnecessary wire jogs/crossings/whitespace. Most old timers like me prefer monochromatic drawings; because that's what we were weaned on.

Here's a recent example from a student:
db4fee30.jpg
Here's how I would have drawn it:
db4fee30edit.jpg
 
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Thread Starter

RexR35630

Joined Dec 9, 2023
17
Welcome to AAC!

It'll be difficult for you until you build some sort of foundation. Make sure you understand the basics like Ohm's Law because that's the foundation you'll be building on.

Until then, enjoy trying to drink from a fire hose.
My first project was a power supply. Except I had an ASEET and, pretty much, knew what I was doing. Still, it's a good first project and you get to use something that you built. Mine was nothing fancy. Dual adjustable outputs, no current limiting, no display (built it in the late 70's when panel meters were still quite expensive).

These days, you can buy a used laptop power supply and add something like an LM317 on the output.

My second was a digital voltmeter using a panel meter that cost me $30.
I don't see anything wrong with the title. But now you know that more descriptive titles are better.
Thank you for replying and your suggestions.

I just tried to create a "Self Made" Power supply out of foam board and hot glue and 5v ac to dc power plug.

I blew the fuse in my Multimeter trying to understand (I) current.
That's when I knew! I need to start from the beginning.
I was using 1.5v batteries but they fluctuate a lot.

1702149440661.png1702149692962.png
 

dl324

Joined Mar 30, 2015
16,991
I blew the fuse in my Multimeter trying to understand (I) current.
I'd suggest that you measure the voltage drop across a resistor and calculate current. You're less likely to damage a meter and, since all DVM's aren't ideal, perturb the circuit and get misleading readings.
I just tried to create a "Self Made" Power supply out of foam board and hot glue and 5v ac to dc power plug.
An AAC member gave me a battery powered homemade experimenter he made from a wooden frame, a couple LM317, solderless breadboards, and inexpensive voltmeters.

I rewired it and added 2.1mm jacks so I could power from adapters. It was a neat idea because a commercial unit would have been $50-100, but the 16340 Li-ion batteries he used were all fakes.

I'll post a picture when I find it.
homemadeExperimenter.jpg
The meter in the middle was configured to measure current. I changed it to read volts. He used 10 turn pots to adjust voltage. I replaced with single turn and added a range switch on the bottom supply.

Here's a commercial one:
digiDesigner.jpg
 

nsaspook

Joined Aug 27, 2009
13,418
Thank you for replying and your suggestions.

I just tried to create a "Self Made" Power supply out of foam board and hot glue and 5v ac to dc power plug.

I blew the fuse in my Multimeter trying to understand (I) current.
That's when I knew! I need to start from the beginning.
I was using 1.5v batteries but they fluctuate a lot.

View attachment 309632View attachment 309634
I like it, you're a builder. That's why basics are important FIRST, so when you blow the fuse measuring current, you know why it happened.
 

Thread Starter

RexR35630

Joined Dec 9, 2023
17
Welcome to AAC.

We all had a beginning. And Dennis beat me to the welcome.

There are things over my head. Some way over and some that just skim across the top - as you can see from the polished scalp.

Basically it comes down to math. Ohms law basically states that all things are related. A given voltage and a given resistance will have that specific amount of current. DC is the easier part but AC is a bit more advanced. Just give it time and don't be afraid to ask questions.

Breaking that down into something simple; suppose you have a resistor in a circuit and a voltage. The resistor is 100Ω (ohms) and the voltage is 10V (volts). That means that 10V ÷ 100Ω = 0.1A (amps) designated as the letter "I" Those numbers can be turned around and still come out the same. If you have a circuit with an unknown voltage but you know the resistance is 100Ω and you know there is 0.1A then you multiply. 100 x 0.1 = 10. You have 10 volts. Since resistance is the thing that is most often a fixed value (doesn't change) you can change the amperage by changing the voltage. More volts and you'll have more amps. 100V ÷ 100Ω = 1A.
E (volts) is equal to I (amps) times R (ohms) ( ( E = IR ) )

That's the most basic part of a beginning. There's an educational section where you can learn from the very most basic to the very advanced. You can go as far as you like.
Thank you for your reply!
Yes, My understanding of Ohm's Law is weak I understand the math of it but one thing still puzzles me about it. I was told to think of voltage as water in a pipe, and a resistor as a smaller pipe to restrict flow but what I don't understand is that regardless if you have one resistor or 10 in a circuit you will still have 0 VOLTs after the last component in the circuit, but even if water flows through a smaller pipe you will still have some water coming out of that pipe. How come in a circuit that only has one resistor there are 0 volts as it returns to ground but in circuit with 10 resistors they all have different voltages after each resistor until the last one? See, my concept is fouled.
Do you have a DVM? Solderless breadboard/jumpers? Soldering iron?

I did electronics as a hobby for more than 30 years before I got a scope (now I have 8 or 10).


Thanks again for helping out.
I'd suggest that you measure the voltage drop across a resistor and calculate current. You're less likely to damage a meter and, since all DVM's aren't ideal, perturb the circuit and get misleading readings.
An AAC member gave me a battery powered homemade experimenter he made from a wooden frame, a couple LM317, solderless breadboards, and inexpensive voltmeters.

I rewired it and added 2.1mm jacks so I could power from adapters. It was a neat idea because a commercial unit would have been $50-100, but the 16340 Li-ion batteries he used were all fakes.

I'll post a picture when I find it.
View attachment 309635
The meter in the middle was configured to measure current. I changed it to read volts. He used 10 turn pots to adjust voltage. I replaced with single turn and added a range switch on the bottom supply.

Here's a commercial one:
View attachment 309637

That looks like fun. Is there instructions for creating something that online?
I'm already excited about AAC.
It is really gonna be nice to come here and get some advice and help!
 

Thread Starter

RexR35630

Joined Dec 9, 2023
17
It sounds like you are hesitant to actually get started. Fear if doing something wrong is likely the cause. The solution is to use only things that can’t do much damage.

Take an old 5V phone charger, snip off the end of a USB charger cable and you have a power supply that will allow you to experiment without danger.

Get some resistors and LEDs, and a solderless breadboard with jumper wires, and we can show you how to apply Ohm’s law to design your first circuit.
Man, That sounds great!
Honestly, I've always been a bit intimidated asking for help on this subject.
I was once kicked out of electronics class in 8th grade cause the teacher said my math skills weren't up to par and he didn't want me to hold up the rest of the class or reduce is GPA of the class.

Thank you and will appreciate any advice and help you are willing to give me.
 

Thread Starter

RexR35630

Joined Dec 9, 2023
17
Do you have a DVM? Solderless breadboard/jumpers? Soldering iron?

I did electronics as a hobby for more than 30 years before I got a scope (now I have 8 or 10).
I do, I just gotta learn to APPLY, I got a lot of stuff, I just now have the time to learn how it all works.
1702151234247.png
 

k1ng 1337

Joined Sep 11, 2020
986
The textbook resource of this site gives an introduction to the major electrical engineering concepts. The examples are limited but the basic theory is there. Take it slow and make an honest effort to do all the math and word problems. Try to build the circuits on a breadboard if you can and take measurements like crazy. Also check out the calculators and other tools of this website.

Textbook for Electrical Engineering & Electronics (allaboutcircuits.com)

Use Falstad circuit simulator to augment your learning. It is technically not accurate but provides a great visual for beginners. In the "Circuits" heading, there is an example of pretty much every basic circuit covered in the textbook link above.

Circuit Simulator Applet (falstad.com)

Most complex circuits are built with building blocks of the circuits you will find in those resources. Learn them piece by piece and eventually their function will become obvious when they are part of a whole. When you are ready, use LTspice circuit simulator.

LTspice Information Center | Analog Devices

I also highly recommended taking at least $100 down to the local hobby shop. LEDs are fun but RC planes and rockets are better :)
 
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