how to create a pcb

How to create a PCB From a Diagram

by Lohan Naude | 8 Dec , 2016 | Projects

How to create a pcb

Converting a circuit diagram to a Printed Circuit Board (PCB) could prove to be a challenging task.

But luckily with technology today it is fairly simple to complete this task, so there’s no need to be stressed out. We will be doing an easy one for today. It is called an A-Stable Multi Vibrator.

First, I will explain the circuit and the working thereof. Imagine that R2 were absent from the circuit, and suppose Q1 started out being turned on. Then Q2 would have nothing to turn it on, and Q1 would be held on by current through R3, while the R4 and the LED would charge C2. The effect would be that LED1 would come on and stay on, while LED2 would never light.

Now add R2. This will cause C1 to charge to -0.7 volts, until Q2 turns on. Once that happens, the charge on C2 would cause the base of Q1 to go negative, turning it off. When that happens, current flowing through LED1 will start flowing through C1 and the base of Q2, turning it on even harder. Once Q2 has turned on, it will keep Q1 off until C2 charges to -0.7 volts.

Note that while the circuit would have a stable state with both transistors on and both capacitors reverse-biased by 0.7 volts, in practice the winky-blink circuit always starts oscillating rather than entering such a state.

We will now start with our process. First download your software HERE for Design Spark or HERE for EAGLE CAD, I use Design Spark most of the time.

STEP1: Layout

,,,hFirst we’re going to place all of the components in the correct place.

flip-flop-raw-schem

It can be a bit difficult to find the components, but design spark has a great function under view -> Model Source Bar where you could either look under categories or enter a RS Components stock ,number just select your country and search your components you need, enter the stock number and click use component the software will tell you in which library it save the component and you can go fetch it from there. Marked in red are the two ways to find the components you need.

finding-comps-flip-flop-schem

STEP2: Connecting

Next we will connect the components together as shown in the image above, note that instead of a battery I have have added a two pole header, when we have the final product we will have two holes where you can solder in the battery leads or you can put headers in those same holes.

flip-flop-schem

STEP3.1: Converting

From here you have a few options. First option is to simply click on translate to PCB.

translate-to-pcb

and follow the easy steps. Your PCB will look something like this

translated-to-pcb

This does not always come out like expected, in which case we will see how to fix this in Step 3.2

STEP3.2: Converting

If your results was not what you expected in Step 3.1, click on Tools -> Unroute Nets -> All Nets.

unroute

You will see that the tracks has disappeared and now there are thin yellow lines. These yellow lines are to show you how the components were connected.

If you chose not to follow the previous option you will have to insert the components manually again. If you did follow the previous option you now only move the components how you feel fit.

This is what mine looks like yours can be different.

option-12-layout

STEP4: Wiring Compnents

For option 1 go to Tools -> Auto Route Nets -> All Nets

auto-route

and follow the instructions.

For option 2 you have to add the track in manually as in the schematic.

Your end result may look different than mine, but in the end, we achieve the same product.

finale

Note: Using option two may result in errors making the PCB useless. Yes option one may have errors as well but only if your schematic was wrong. Some of these errors may prove to be fatal.

I hope this blog post gave you a starting point on how to create a pcb.