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Conceptualizing: Moving from Schematic / Wiring Diagram; to Finished Circuit

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quicksilver

Mon Jun 02 2008, 02:18PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I need a guiding hand with a question that may seem VERY elementary to many but I would really appreciate any help.....

I have a question I would love to hear varied opinions on......When I see a schematic or wiring diagram with most of the values available, I have heard &/or seen varied methods of making that schematic "live" as a real circuit. I have seen folks spread wires all about a table, some use a breadboard, & others have unique methods that seem to have a "finished" appearance from the very start.

My question deals with the ways people with experience make a schematic function as a finished circuit.
I have tried using a breadboard but to my inexperienced mind, they seem too confining and small. I have certainly tried simply spreading wires upon a table to map out the circuit and that seems a very common thing to do. But in so doing I find that I am constantly fighting shorts and the jumble of wires doesn't lead to a clean finished design until I have done the same circuit many times & start to see where the simplifications can be made.

If I were to simply take a schematic and wire it up as it's printed, the finished product seems to waste space and wire. It's generally overly large. People DO put all that into a breadboard but they have a way of conceptualizing that I'm missing - in my inexperience.

Is this simply an issue of experience or is there an engineering technique that allows for a way of thinking that takes a person from schematic to finished product? Thanks for any input or opinion. I know this is a very individual issue but I would love to hear how some of you do this as many of you produce items of a quality SO high that I would love to hear what goes into that final product!

flannelhead

Mon Jun 02 2008, 02:44PM

Registered Member #952 Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388

I'm not an expert on making my circuits look high quality, but... When I print out a circuit, I usually take a sheet of paper and make a simple draft of a perf/veroboard layout. Then I assemble the circuit on the board and possibly test it part by part (for example, build the oscillator first, scope it to be sure it's oscillating, then build the power part.)

I try to make the circuit look nice by avoiding too long wires etc. Also one good point: if your project isn't up to board size, then there's no reason making it as small as possible. So if you have space in your project box, feel free to use board space! Often it looks a lot cleaner.

If you do the planning well, you can make even a veroboard layout look very nice! Some people have so much experience that they just throw the parts on the board and solder them together without any planning, and it still looks nice. I would prefer making a layout with just a pencil and an eraser. It's often easier than using any layout design program.

Avi

Mon Jun 02 2008, 03:13PM

Registered Member #580 Joined: Mon Mar 12 2007, 03:17PM
Location: Melbourne, Australia
Posts: 410

I don't think finished circuits are supposed to be understandable by just looking at it, that is what schematics are for.
I often just make a mess on the table with clipleads.
for a permanent circuit, i use veroboard and design it with expresspcb, such that underside links run crossways, and all other wires go ontop running in the up/down direction. It it very tiresome and difficult (at least for me) which is one of the main reasons i often don't bother.

quicksilver

Mon Jun 02 2008, 03:16PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Building the oscillator first is a VERY interesting idea! I had heard that a speaker would tone if many transistors were in oscillating; thus short-cutting the concept of completion till other areas were laid out.

I'm hoping that this thread will continue as each person through their successes & failures has unique ideas that may help beginners for years to come. I too use clip leads in Avi's example and had come to find that some frustration can be prevented by circumventing this. Often I've found that my schematic interpretation was just fine but my clip leads were shorting or malfunctioning.
Some folks have "tricks" that they enjoy - that speed up the process & almost become a personal style of building.... I only hope that they will share them!

Steve Conner

Mon Jun 02 2008, 03:18PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Circuits generally look nothing like the schematic, and there is no fixed way of mapping from one to the other. If there was a simple set of rules, I'd be out of a job and so would a lot of other EEs, since we could be replaced by software.

When I was learning, I found it very helpful to study commercial products like TVs and VCRs, by picking broken ones out of dumpsters and trying to fix them without any schematics or service manuals. I found this really difficult at first.

One idea that might help is that the length and shape of the "wires" drawn in a schematic have nothing to do with the layout. The only important things are the nodes: the places where wires join components and each other.

Wolfram

Mon Jun 02 2008, 03:48PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

When I make circuits on veroboard, I usually wire them up with magnet wire. The advantage is that you can put all components very tight together and there will still be enough room for the wire.

Magnet wire, if not too thick, is very easy to strip, the enamel usually melts away when you try to solder to it if the iron is hot enough.

My main focus is often to make circuits as compact as possible, so I often end up using SMDs on the underside of the veroboard. This is not too hard when you get the hang of it, and it works wonders to reduce the size of the board.

I've had to make changes to circuits made this way, and it's extremely simple. This is one of the main reasons I prefer this method over etched boards for prototyping and things that need to be finished quickly. For fine-pitched SMD ICs, there's no way around etched boards though, especially if things need to be compact.

An example of a board I made around a year ago. The underside looks a bit messy, but this was one of my first boards made this way.

Anders M.

uzzors2k

Mon Jun 02 2008, 04:06PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

The ability to see a schematic and successfully put it on a breadboard is the probably the largest hinder you'll meet when doing hobby electronics, and simply takes experience to overcome. I remember struggling so much with 555 timer circuits that it took several ties before I got one to work. I even managed to make one release it's magic smoke while following a LED blinking schematic. Eventually you'll get the feel for it though, and it becomes incredibly easy. At least on veroboard, I've never make a PCB before which seems to be a whole different matter.

One thing that helps is understanding how the circuit works, and memorizing it. Knowing component pin outs by heart is a must. I know the 555, TL494 and standard op-amp, transistor and PIC pin outs. Not having to check these really reduces the room for error when testing or building. When actually building a schematic unless it's one I just found on the internet or has a some huge chip in it, I tend to visualize the schematic in my head, and think through the flow of the circuit while building. That way I know if I've missed something, because either the circuit isn't complete or a function is missing. For quick breadboard work always place an IC first, then add support components to it. Building the circuit in modules makes it much easier.

Once you've built the circuit on a breadboard, transferring it to a veroboard (am I getting the names right?) is a peice of cake.

Avi

Tue Jun 03 2008, 04:43AM

Registered Member #580 Joined: Mon Mar 12 2007, 03:17PM
Location: Melbourne, Australia
Posts: 410

I should add that if you use clipleads, you MUST solder the internal connections inside them! the crimped connection is useless!
If you work with high frequencies, you will begin to see the inductance of the leads making your signals look bad, so probably best to consider putting it onto a board at this point.

teslacoolguy

Tue Jun 03 2008, 05:18AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

When i first started to work with electronics i found it very very hard to get the circut right from a schemattic and it usually took me 6-7 try's to get a 555 working and with a lot of jumpers on top of the breadboard. Now i have it mastered and i can whip up a 555 circut from my head in about 5 min.

How i used to solder.

How i solder now.

...

Tue Jun 03 2008, 06:24AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

It all depends on what you are doing...

For quick lashups I will generally put everything I cna in a breadboard, and the other stuff (anything carrying large amounts of current) will be wired together next to the breadboard.

For when I have something simple that I just want done perfboard is the way to go, but the key is to not put wires in the underside, leave them on the top. I find this helps keep the board a lot more usable on the long run.

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But for anything that requires a lot of power, or has a lot of parts in a small aread a pcb is necessary....

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