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Protel Autotrax
What is Autotrax?
What is the Purpose of this Site?
Installation - Tasks 1 and 2
Installation - Tasks 3 and 4
Installation - Task 5
Installation - Task 6
How it Works
The Resizing Problem

Let's Design a Circuit
Now Draw It
Place Components
Adding the Tracks

Aston Home

Let's Design a Circuit.
(And make a PCB for it)

Let's say we want to design a circuit to flash a light.  It might not sound much but it's the "Hello World!" of the electronics lab.

But we are goint to do it using the Modified Smith Astable Multivibrator for no reason other than we can do what we like and not one can tell us otherwise.  Except on the Internet of course, where everyone can.  And does.

"Can someone help me?  I want to load Office 97 on my XP machine"

- "Office 97 is very outdated.  You should load Office 2015 instead."
- "Why are you using XP? You should upgrade to Windows 10."
- "You're an idiot."

Here we are going to do this my way and if you don't like it - tough.

Here's the circuit.  Plug it into Linear Tech's LTSpice and watch it work.  You can cheat and download the circuit by clicking the image.

Not much use if you can't see it.

The 1N4148 is your LED.  There isn't a neat LED on LTSpice but it makes no difference.  You first task is to understand it.  Haha.  Only joking.  

Akcherly, it's a variety of series astable of which there are a number.  You can Google for it or download the Ferranti - E Line Transistor Applications 1974 from wherever Google located it but wouldn't tell me.  Or from me here (at least until some killjoy bleats about it in which case I'll post a link to their site or remove it altogether).  You can bleat to me about some mincing breach-of-copyright-for-something-that-isn't-yours-anyway at