Hi All

I am new to this site, I live in South Africa, can't remember if I already introduced myself... Been very very busy at work... I work for Fluke here in SA.

Getting back on the Electronics band wagon!! Looking forward to it!!!

One question I have, I get very bored with the small details of different electronic parts when learning them individually and I do understand that I need to learn it. But I would like to learn some more of electronics in a different way. I want to design and build stuff... (with this in mind, with only surface info of what something does e.g. a capacitor stores a charge, resistor resist flow of current etc.) If I want to decide to build something I would like to know where to start. What process I need to follow etc. I do find a lot of information on electronics on the internet, but not really design based.

One guy I know that works at the South African Farnell distributor said that it is good to learn by taking simple circuits and analyzing them to understand more of what is going on.

I want to take the design route as well. . .

Thus my questions. Where would one start when designing something, I was thinking for example, whatever you want to drive (a garage motor opening a garage door) for instance and work your way back to the power supply? Is there a certain procedure you got taught that few of us know?

I hope you can gather that I would like to take the hands on approach... I am quite good with the Digital Electronics, but need to touch up on the rest.

Thanks in advance, specially for the great site and forum!

Regards

 

There is no short cut to learning design that I am aware of.
You have to begin and be thorough with the basics.
I am not aware of any design course that will allow you to skip the basics.

So you know a little bit about resistors and capacitors. That is a good place to begin.

What happens when you put two resistors together?
Get out your Fluke meter and experiment.

Add a battery.

What happens when you put a capacitor and resistor together?
Add a battery.

Add an inductor.

Learn everything you can about R,C and L circuits until you can explain it all to a seven year old.

Add a battery.

Then replace the battery with a 60Hz signal.

That is where design begins.

 

Thanks MrChips

This is also a good idea!

Sometimes I think the Internet takes away ones ability to think for oneself, after I posted the abovementioned I went searching for Circuit Designing on AAC after I posted this.

I could have just as well searched for it and not ask this question(s)!!

 

Motivation is one of the key "lubricants" to education. Learning for the sake of it can be slow, but the motivation to accomplish something changes the pace. So if you find a project that interests you, attack it. I've learned more than I ever thought I wanted to because I HAD to, to advance a project I was working on.

Pay attention to the basics as you advance from understanding individual components, to understanding common combinations of those components. For instance, the combination of a resistor and a capacitor is an RC circuit, and is used everywhere. Putting a resistor to ground on the emitter of a transistor gives you an emitter-follower amplifier. Four diodes can give you a rectifier.

The point is, over time you'll realize that large, complicated circuits are built up from smaller, simple circuits that you can come to recognize and identify. A designer does not reinvent the basic component circuits - he knows they exist, what they do, and where to apply them to get the job done.

 

Hi WayneH

This is exactly what I was thinking of...

I have built power supplies before and have built some kits etc. I just pulled apart a Fluke 177, 117 and a Amprobe meter here to study it a bit. And I agree with the method of paying special attention with the smaller details as you move along a project. Even if the project takes an extremely long time to complete. My question might not be all that clear, as they usually aren't. Lets say one knows a lot of electronics, how do you go about a new idea/project.

For example...

Think of this as a initial 1st person. Back to the Garage Motor: "I want to automatically open my garage. How do I do that? What is the weight of the garage door? What size motor do I need to run to be able to lift it? When it comes to the top will it automatically stop? No, I have to put in a limit switch or something... Same at the bottom. Ok designed that... But I'd like to add another aspect to this system, I think I need to add a remote control.... Blah blah blah"

Now here is where I have the issue, I understand writing out a project as above. Using design blocks and flow charts etc. Experience will give you the different circuits to use where (this I need a lot of). And I think I got the point that should one not have the experience, it will be hard to determine what circuit to use where. But what if you want to add something? Do you need to change the other circuitry to include this? Do you need a larger supply? Etc.

My idea behind designing is the above mentioned. Is this correct or is it just a mess? Writing everything out that you can think of, start with the end (motor pushing up the garage door) and work your way backwards to the power supply and other things you might enjoy.

I understand there is no shortcut to designing. But there should probably be a taught proses you guys can think of or that is taught.

 

I just got LTSpice, I will play with it a while! Thanks for this guys, foudn it while snooping around AAC

 

The first step in a good design is a good spec. It will save you a lot of trouble later on. So figure out everything you really want and need to do before you worry about how to do it.

 

Having learned about the basics of resistors, capacitors, inductors, diodes, transistors etc. you can move on to a design stage with the use of building blocks without having to worry about how each block is implemented:

preamplifier
amplifier
buffer
inverting amplifier
summing amplifier
current to voltage amplifier
voltage to current amplifier
constant current source
constant voltage soure
differentiator
integrator
log amp
exponential amp
low-pass filter
high-pass filter
band-pass filter
rectifier
peak detect
comparator
pulse generator
power amplifier
oscillator
multiplier
phase detector
phase-lock loop

etc, etc.

Have I missed anything?

 

The first step in a good design is a good spec.

+100
A little "mission creep" is normal, but you really need a detailed specification to work towards. It defines the constraints that you are designing around. Mission creep might include adding LED indicators, anticipating expansion or whatever, but the main mission must be clear and some specs are absolute. Discussing your project in this forum will be much more effective if you can communicate the specifications you need.

In your garage door example for instance, it would be critical to know if you need to protect against squishing cats and babies with a force detector. It won't change every aspect of the design but it is certainly an important specification. It's maddening for the helpful folks around here to learn of important specifications that aren't mentioned until we're well into a design.

 

Okay MrChips! This is actually a nice way for me to understand!!! I like this!!

Only thing is with these building blocks you make sure all values are what you need for your project. That is if you have everything you want down on paper!! As mentioned by RonV.

Another question though, how does one determine the size of supply voltage with a new circuit design? Is it one of those other rules, A network is equal to a single resistor in series with a supply voltage etc...

I like understanding the bigger picture first. That is why I want to go this route with projects. but keep in mind, electronics from a computer for example is too much of a BIG Picture

 

How do you size the power supply?

Like everything else you make a list of the power requirements for every stage, voltage and current.
Of course, in order to make life simple, you want to try and keep the supply voltage the same for every building block. The voltage you choose will depend on the application. There are some commonly used voltages, depending on power demand and portability etc.

Here are some typical supply voltages:

3V
5V
9V
12V
15V
24V
+/- 12V
+/- 15V

A typical op-amp stage could require anything from 1mA to 20mA depending on the op-amp and the circuit design. Micro-power circuits can run on much less than 1mA. Record the peak current required.

Then you total up the current and give yourself some headroom.
If your total comes to 200mA then use a power supply that can supply 300mA, minimum, for example.

 

Thanks Wayne, I'll remember that!! A little Mission creep is acceptable...

 

Okay..... I admit.... A "thought process".... That just sounds stupid! It was late last night here and I haven't mastered the skill of working with only 2 - 3 Hrs sleep. Wish I did!!! Could build a lot of toys!!!!

Thanks for the assistance gentleman! I'll see you around on the AAC Forum...