Circuit Design for Beginner's.

[xl5]

Simply where do i start to build a simple circuit using ie say the ic 555 or 741 respectively, perhaps the cmos range of ic's also.

Looking at the data sheets of these ic's is the beginning perhap's and i want to try my hand at say a simple cct, small timer/ amplifier. using appropriate resistors/ capacitors/diodes/leds/ photocells etc.

My previous job measuring voltage/current/ resiatance/fault finding had no need for cct design...

Now let's have your advice please.

 

[Sceadwian]

allaboutcircuits.com has a lot of theory and basics that you may not know about have some experimental circuits you can build. Aside from that search on Google, you'll find more circuits that you could build in a lifetime, especially those using the 555 timer and discrete components. Pick something small that you understand basically and try to build it, if you have questions throw them in a thread on here and people will try to help.

 

[kakin]

if you need a simple 555 circuit maybe a flasher will do, I have a 555 flasher circuit at my blog if you want to check it out

 

[stevez]

You may want to have a look at a series of articles published by the ARRL in the monthly QST magazine. Many of the past articles are now bound for sale. The articles include some discussion on electronic theory as well as experiments or construction that can be done to supplement or reinforce the learning. I thought that the coverage of electronics as a whole was excellent. "Hands On Radio Experiments" is the title of the book and I see it is listed on the RSGB (Radio Society of Great Britain) website.

As I recall the experiments were such that relatively common parts were used and that the parts were useful over many experiments.

Rather than purchasing a book you might try to contact some local radio amateurs for copies of the articles.

Good luck.

 

[condor36zw]

Welcome to the hobby!!

Hi XJ5. I'm fairly new to this forum, but not at all new to electronics. The only advice I can give you, is to go through the steps, slowly. Whilst some components can give you spectacular sound and light (and smells) displays if connected up wrong, it does get expensive. Consider getting yourself a proto-board, or breadboard as it is sometimes called and wire up a few circuits on that. But to wet your appetite, please see the attached file which I have done for you. I have a small company doing products for the model railway fraternity, and this is a level crossing flasher circuit. Why I chosen this circuit is that it is far more educational in that it doesn't use ICs like 555s, but rather discrete components like transistors etc.It also has some other unusual aspects in that it uses electrolytic capacitors wired back to back to give you what is called Bi-Polar Electrolytic capacitors.

1)Print out the PDF file onto a sheet of Photo Quality Ink Jet Paper with a laser printer.
2) You then cut out the circuit board layout, the one of the copper tracks, and get a piece of copper laminate blank circuit board.
3)Thoroughly clean the board with a kitchen scourer pad and with rubbing alchohol, sometimes called Isopropyl Alchohol
4) Use a normal clothes iron and iron the paper onto the blank board using the hottest setting. Really work the paper with the iron. The copper will get really hot so be carefull of those fingers. This could take several minutes of ironing.
5) Finally, drop the whole thing into warm water and leave it to soak for a few minutes. You should be able to then peel the paper off the copper leaving the traces intact.
To etch the board, I use good old Ferric Chloride, but there are other postings here of other chemical formulations. I normally pour a little ferric chloride into plastic container, and pop this into the microwave for a few seconds to warm it up a bit, but only when the missus isn't around. The warming (not heating!!!) helps the ferric chloride do its job. Please wear gloves and goggles with this stuff. It's nasty. And don't pour it down the sink. Your pipes will go, and it would not be considered very Green of you. Returned the used chemical to the bottle it came in. In can be used over and over.
Hopefully you've got a small drill, to drill the holes, but if your gonna do this hobby, it might be an early acquisition if you want to make your own boards.
6) What I then do is iron on the component side (notice this is a mirror image) so you know where everything goes, but you can also just use the component overlay on the PDF i've given you.

If you want to tackle this project, I'm sure you will have lots of questions. Just email me (steve.verwey@vodamail.co.za), or better still post them, and I will reply. If you ask me nicely, I will even knock up a board for you. View attachment Composite.pdf

Incidentally, the circuit design is not mine. I can't remember where I got it from, but thanks to that person. The board layout is mine however.

 

[condor36zw]

Sorry forgot to mention, the reason for several copies of the same board on the PDF, is when(and I mean when) you cock it up the first time, you have lots of spares.

 

[VideoGuy]

I would agree with getting a breadboard that allows you to experiment and find what does work so you can be confident in soldering it later. Radio shack (shudders) has one good product for beginners, (I still use mine). I don't remember what they call it, but it is a kit of various components, a breadboard, and some panel lights, speakers, and switches. It comes with a book or two with many projects that you can build. Very helpful to learn from.

 

[Mikebits]

Hmm, starting a design, some might say you need a strong background in what your designing. Sure, this will help, but is not always a requirement. Many designs I have done in a professional capacity where I had little background in the technology needed to achieve a functional design. So how do we start? Here is how I have learned to do it.

First, we must decide what our widget is suppose to do. Start with inputs and outputs of your widget, and secondly the specifications for the inputs and outputs. These two things are important. We start our design from the outside in.

Let's say we want to design a fart detector. What inputs and outputs do we need?
Well, that depends on our specifications. Does our spec require detection of a certain level of fart (let's say -10 stinky's) or just a really stinky one? Also for the output spec, in case of a valid input, should a display provide level of stinkyness or do we just sound an alarm warning people to escape and hold their breath while they do so? These are the spec and I/O questions we must answer and address in our initial design.

In this case, and for simplicity, our fart detector only senses a fart and sounds an alarm at say +5 decibels.

At this point we have not designed anything, only defined design I/O parameters. Now we must work out our design. We know that two things are needed, a fart sensor and an alarm device. So we get on our search engines and look for fart sensors and we want one that is sensitive enough to measure -10 stinky's. At some point we find a fart sensor that meets our spec, so then we look for an alarm for our output device. We eventually find both part to meet our I/O spec.

At this point we have a good idea how to approach our design, we have inputs and outputs and we have devices to perform the functions. Now we might want to make a block diagram based on our sensors where we attempt to define a method to interconnect our two I/O devices. For example; the fart sensor operates at 1.8 volts DC and the alarm device runs at 12 volts DC, so on our block we need a power supply block that creates these two voltages.

Our fart sensor is analog and our alarm is simply a logic one or zero, so then we must approach a method of dealing with these mixed signals. One may require more Googling and research to solve these interconnect problems, but as you work your way outside to in you get closer to a working design.

Well, in a nutshell, that is how I do it.

 

[condor36zw]

LOL @ Mikebits

So Input Beer...Output Fart. Now we're talking. And then we have to discuss the Central Processing Unit