Circuit design...

[geckzilla]

I know I could Google this, but I think there are some DIYers here who could point me to the appropriate software much more quickly than Google could. I've got a circuit design, but in its current layout it won't fit in my enclosure, so want to create a longer, skinny version instead of a square. I already put one together just by translating each piece one by one, but I think it would have been much easier if I could have had some software that would let me click and drag a section of the design to a new configuration and then redraw the connections to more closely match reality. It sure is confusing to try to follow lines around when the orientation and design is different from what you're working with.

[Chris Peterson]

I know I could Google this, but I think there are some DIYers here who could point me to the appropriate software much more quickly than Google could. I've got a circuit design, but in its current layout it won't fit in my enclosure, so want to create a longer, skinny version instead of a square. I already put one together just by translating each piece one by one, but I think it would have been much easier if I could have had some software that would let me click and drag a section of the design to a new configuration and then redraw the connections to more closely match reality. It sure is confusing to try to follow lines around when the orientation and design is different from what you're working with.

I'm not quite sure what you're asking. Is this a reference to your circuit design tools (schematic capture and simulation) or to your PCB layout tools? What are you currently working with? Most PCB design tools allow you to move parts or regions around and they will be partly or fully autorouted. Schematic capture tools let you move components while maintaining connections. Or are you saying you're doing this all manually right now, just using some graphics tool?

[geckzilla]

It's just a jpg of someone else's design. I'd have to remake the design in the software and then drag it around to my liking. I have absolutely no idea what the name of software can do this and I'm just assuming it exists. I have never done this before.

[Chris Peterson]

It's just a jpg of someone else's design. I'd have to remake the design in the software and then drag it around to my liking. I have absolutely no idea what the name of software can do this and I'm just assuming it exists. I have never done this before.

The normal process from a design standpoint is that you use a piece of schematic capture software to enter your electronic design. Frequently the component library you draw from contains mechanical information, as well. It's also pretty common these days to run your schematic through a simulator that lets you verify most of the design. The output of the schematic capture is a netlist, a file which describes all the node interconnections. That goes to a PCB layout program, which is where you physically place the components and route the wires between them (usually a pretty automated process, although a few years back it was completely manual and required a special kind of mind). The output of that program goes to a PCB fabricator (and with the tiny surface mount components in common use, it may also be robotically populated with parts and soldered).

I don't think there's any way to easily do what you're trying, working just from an image. If you can get the original design as the schematic capture file, you could change things around much more easily. There are many free schematic capture and PCB layout tools available online. Most companies that provide hobbyist or prototype PCB manufacturing also provide such tools.

What is it you're putting together?

[geckzilla]

It's a simple electrocardiogram that Pat started and asked me to help on. I pretty much do not know what I am doing but I can follow instructions. I have been learning how to solder and am nearly done with this first attempt but am ready for it to not work and to have to redo it. If I redo it, I now know that I want to customize the schematic to reduce the potential for errors and make the breadboard easier to read and debug if necessary. It is simple enough that I didn't think it would be a big problem to copy this image into the schematic capture software. Of course, the PCB layout program sounds useful...

[Chris Peterson]

It's a simple electrocardiogram that Pat started and asked me to help on. I pretty much do not know what I am doing but I can follow instructions. I have been learning how to solder and am nearly done with this first attempt but am ready for it to not work and to have to redo it. If I redo it, I now know that I want to customize the schematic to reduce the potential for errors and make the breadboard easier to read and debug if necessary. It is simple enough that I didn't think it would be a big problem to copy this image into the schematic capture software. Of course, the PCB layout program sounds useful...

I hope it's battery operated, or has the electrode amplifiers optically isolated from the rest of the circuitry (especially if the output goes to a computer). Otherwise, it could be very dangerous. As in potentially lethal. You need to be very careful with ECG, and to a lesser extent, EEG amplifiers. Even a 9V battery can produce a lethal current through cardiac electrodes if something fails in the circuit, and if it plugs in (or is electrically connected to a computer, say through the sound card), all bets are off.

[geckzilla]

Heh, yeah, such warnings were already given in the instructions.
http://www.eng.utah.edu/~jnguyen/ecg/instructions.html

I will have to test it on a goat first...

Just kidding.

[Chris Peterson]

Heh, yeah, such warnings were already given in the instructions.
http://www.eng.utah.edu/~jnguyen/ecg/instructions.html

I will have to test it on a goat first...

Just kidding.

Hmmm. Not one of mine, please. The JFET inputs don't provide any real isolation, and those particular devices require a fairly high voltage to work well. I'd suggest you use the lowest voltage battery that works (not a plug-in power supply), and that you only attach the output to a laptop running on battery power, not plugged in to its charger.

Seriously, people have killed themselves with ECG amplifiers. Even with commercial ones before they all went to optical isolation.

[Ron-Astro Pharmacist]

Yes be careful. They actually showed this to us in a CPR class. Guess to get us in the mood.

Click to play embedded YouTube video.

[geckzilla]

Yeah, thanks for the safety lesson and the Mr. Bean video. I guess I'm on my own on the software. lol

[Ron-Astro Pharmacist]

Geck – You're resourceful. Just remember, "If at first you don't succeed, fry, fry again"! Good luck and have a great weekend!

[Ron-Astro Pharmacist]

Did you ever find a suitable answer to your question? Chris helped but I just jested. As you said you could Google it as easy as anyone but this link looked functional and their breadboard looked long and skinny.

http://www.ijesit.com/Volume%202/Issue% ... 303_63.pdf

Also, did you know automated external defibrillators (AED's) have a functional ECG and are readily available – though fairly spendy. You probably know that too as, it sounds like, the project is already underway.

Interesting project; amazing what you can get to hear about and learn from on this site. Breadboards, PCB's – I never had wandered into that common part of today's world other than being around ECG monitors, mostly in the past, and wondering - how does that thing actually work?
(Need a "scratching head" smile.)

[geckzilla]

I kind of stopped working on it because the safety concerns were so disheartening. That version was supposed to be the safest version.

[Chris Peterson]

I kind of stopped working on it because the safety concerns were so disheartening. That version was supposed to be the safest version.

I don't know. I just googled "ecg amplifier" and a zillion very simple designs show up, many with optically isolated outputs (and newer amplifiers that run on lower voltage than the ones in your circuit). Most of the designs have a driven body ground, too, which will give much better results than simply using the circuit ground.

[geckzilla]

I don't even think the exact one on that page is the one I'm using. I'd have to ask Pat. I can't find the schematic he gave me on that page. He was looking this stuff up and said this one had more parts but was also safer. I thought he knew a lot more about what he was doing but it turns out he doesn't bother to look up a lot of things like simple tutorials on how to solder. I do know that the op amps we have are LM342's and not the LF353N's on that website. Anyway, I don't want to work on the thing by myself. I just don't know what I'm doing and I don't think Pat does, either.