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PCB design and cicuit simulation software Answered

Hi all first post here
could someone recommend a good software package for PCB and circuit design and simulation on a budget preferably compatible with windows vista and 7 and with CNC capability (looking to build one in the future)


OK I tried LTSpice

I built this Schmitt Trigger Inverter Oscillator in LTSpice and the real world.

No matter the Capacitor the DM74LS14N IC will only oscillate with a feedback resistor Value of 300 Ω to 3 kΩ.

It works in the real world but not in LTSpice, in LTSpice I could not run a simulation. Kind of defeats the purpose of a simulator.

For a simulator I find it not very satisfying.

I tried and liked Dipspice.

It took me a day to get the hang of the program.

It looks good for designing PCBs but it doesn’t simulate circuit functions and I don’t like the wire jumps.


Oscillator Post.bmp003.JPG

I just simulated the 74LS14-Squarewave oscillator with no problems...
Rebuilt it in real and f was off by 2.1% which is propably due to the crappy cap i used (Electrolyte is quite horrible in terms of accurancy)...

Please post your libs, models, syms and of course your ASC here. Then i will check out whats wrong with it. :)

Also i dont quite understand your sentence
"No matter the Capacitor the DM74LS14N IC will only oscillate with a feedback resistor Value of 300 & to 3 k&."
Do you mean in reality or in the sim?
In reality thats not the case and you can take whatever combination you want to satisfy the normal formula of the frequency,

I'd be interested in seeing your ASC files. I have to admit to being so old-school, I generally work things out on paper, but LTspice is fun to play with. One of the first things I did when I graduated was a numerical simulation of a linear power supply. Took me weeks. The first thing I did with LTspice was the same thing. Took me 2 hours. 1:55 of which was learning the system.

Version 4
SHEET 1 1332 680
WIRE 16 48 -48 48
WIRE 144 48 96 48
WIRE -48 144 -48 48
WIRE 0 144 -48 144
WIRE 144 144 144 48
WIRE 144 144 112 144
WIRE 160 144 144 144
WIRE 416 144 272 144
WIRE -48 192 -48 144
WIRE -48 288 -48 256
FLAG -48 288 0
SYMBOL 74HC\\74hc14 48 96 R0
SYMBOL 74HC\\74hc14 208 96 R0
SYMBOL cap -64 192 R0
SYMATTR Value 10µ
SYMBOL res 0 64 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR Value 1Meg
TEXT -56 344 Left 2 !.tran 0 60 0 startup uic
TEXT -56 376 Left 2 !.include 74LS.lib

See http://www.bilderload.com/bild/282360/squareI0I4D.png for the thing in action

Thanks. That worked, once I'd found the library !

Was that a MM74LS14 or an SN74LS14 or a DM74LS14 or a HD74LS14 all though they do the same thing in embedded binary codding they react differently in the real world circuits.

I do it in the real world, if I say it cannot be done I am wrong, if I say I did that, I did that.

It was a SN74LS14 i used and sim'd.
Other LS than SN are nothing to be found anymore where i work... Even for this SN74 i had to look for a long time...

I used DM74LS14N and have MM74LS14 HD74LS14 SN74LS14N in stock. Mind you I have over 100,000 components in stalk in my home lab.
However no matter what I do I can’t get it to run in LTSpice.

100k?!? Wow... You lucky person :) I wish i had access to 1/10th of that at the company...

Maybe there is only a little problem... Please post your ASC, LIB and SYM of the schem/the parts or tell me from where you got the LS-parts since they arent (anymore) part of the normal librarys supplyed with LTspice. Then i can check it out and maybe find out why it doesnt work...
Maybe there are simply some hidden powerpins which need a powered VCC-Label placed in the schem...

I was an electronics technician and owned a repair shop in the city before I got my engineering degree and everything went disposable. So some I bought and some I salvaged

I would give credit on working obsolete electronics and salvage the gold, silver, aluminum, copper, and working components.

Many ICs in older computers just plugged in so I removed the ICs and cut off all the gold baked off the copper.

Most of the time the gold, silver, aluminum, and copper paid for the credit. I got a bunch of studio video recorders at an auction for pocket change once they had 1lb of gold in them and over a hundred plugin ICs each.

Other than my TTL books I go to these websites for Data sheets on components,

A list of my ICs would fill two pages of four columns I can send it in a PM if you like.


Cool, Joe! :)
Since i life in Europe, the cost of sending me single ICs would be not worth the hassle... So the list is not needed.

I dont salvage much and getting the cold off electronics scares me a bit because of the aggressive chemicals involved...

I have installed Fritzing, although it is a PCB design software it does not work as a circuit simulation software.

I simulate a lot with LTSpice (free) from Linear.
CadSoft EAGLE PCB Design Software is free for private use and gets used in the DIY-scene quite a lot.
I use Altium Designer (Costs big $) since i am allowed to use a license of the company i work for.

You man your antivirus goes also bonkers about eagle? Your antivirus has a serious Problem! Hat av do you use?

Microsoft SE is kicking it out.
Somthing about them not being signed.

well... Yes. Of course.
A LOT of independent coders and software-companys dont have the money or the time to let their code sign by microsoft.
I for instance looked ONCE onto this matter with software i wrote for my company. We VERY fast turned around 180° and never looked back. Sorry, but the signing of MS is just B.S. for all opensource out there.
You can keep MS SE on if you want and thus block around 80% of all opensource-tools and freeware out there. Your choice.

I run with AVG (Antiviral Grisoft, free) and since a few months with Avast! (Also free) and never had any problems.
And IF a tool gets flagged, i always have the option presented about allowing the thing or quarantine it.
Looks like MS SE doesnt offer you such choice, eh? Another "why" i would never choose my protection from the same company as my OS...

I have AVG also my computer only started doing this since the last microsoft update a couple days ago.

Seems like there was some sort of Auto-Configuration of MS SE then which trys to block all non-signed tools. No way to turn that back to normal and only make a popup with a info "Hey: Not signed. Executy anyway?" [YES] [NO]

LOL! I just found a MS-Knowledgebase where they admit that in certain cases Microsoft Outlook 2010 is treated as unsigned and deleted. LOL!!

Here is how to temporarely disable MS SE:

here is a workaround which may help: It was written for an installation of Microsoft Internet explorer 6 (LOL! Even their OWN SW isnt signed...)...

I am checking out Diptrace right now actually I’m going to bed.
Diptrace downloaded fine once I figured out the schematics the auto configure and auto route is wicked just no circuit analysis.
Will try tomorow got to be up in 4 hr.

Also http://windows.microsoft.com/en-US/windows/getting-started-with-security-essentials gives a hint:
"If you want to delete threats automatically whenever they are identified, open Microsoft Security Essentials, click the Settings tab and then choose Default actions."
Check if those default actions can be changed from somewhat like "Silently kill" to "Ask" or something along the lines...

Electronics Work Bench is good.
If you are in school some of the student edditions are free.
but the pro eddition ouch on price but data on almost everything.

Do you mean NI Multisim?
I used that in the past but had mixed results in chip-behavior...

I bet it was the student addition or the assessment download.
They made those limited in what they can do to get you to buy the pro addition.
I liked it for the ease of use and printing schematics over cad programs.
I do my designing in my head and print schematics from paint now.
I have a few tricks they don’t teach in school from before the PC like a transistor at Q.
Transistor Z at Q = Zc + Ze
All electronics simulator programs are virtually out of date as fast as you can load them into your computer. New chips and chip behaviors every day some of them are updating more often than circuit designing.
Heck your computer was out of date before you took it out of the box when you brought it home that’s how fast electronics changes every day.
One thing almost all the programs miss is transient signals in embedded programing this is caused by the simulator program using Ideal models in the designing.
There is also the programmer syndrome of the programmer that programed the simulator.
Have you heard the Press Any Key joke?
Where is the Any Key?
Every time I hear that joke I take the car keys out of my pocket and press them saying didn’t work.
That is programmer syndrome.
Got to go.

Thats why i like LTSpice from linear.
They update quite often and a lot of the models dont sport an ideal response but a real one.
See, lately i made a trigger-detector with an 40106 and LTSpice correctly sim'd the lowerers VCC and denied a triggering because both the VCC and the signal lowered proportionally.

You got it from http://www.linear.com/designtools/software/ right?
You got the file http://ltspice.linear.com/software/LTspiceIV.exe right?

I never had seen it flagged before... Norton Endpoint (At work) and my own Avast! never tagged it.
Wait a sec...

OK... I just sent in the file linked in this post (LTspiceIV.exe) to virustotal and it came out clean:
All known (46) Antivirus-softwares available there told "Clean".
See https://www.virustotal.com/file/ae53c09001d67dacc3a3703099b5b7a9be8675ddb86367856b6d881a60a02a22/analysis/1357695123/ for detailed report.

I don't know what it is but the only action my computer will alow is delete the download.
I does this when somthing in the programing is modeled like a virus.

Diptrace is great for schematic and pcb. Its free.

I am checking Diptrace out and as far as I can see other than planning a printed circuit board I find making schematics in pant easier. I just can’t get the components to rotate to the angle I want in Diptrace.

Diptrace really looks cool! The 300-pin-limit in the free version should be of no big limit for a normal DIY-project.
Also it is nice to see a DRC (Design-rule-check) as i know it from altium.
Thanks! This one gets a link in my software-catalog for sure :)