Learning to fail and how you move on from it: In my previous two posts I had designed and created a pcb layout for a simple 555 timer flasher. I thought it would be a simple thing to do because I really wanted to test the workflow on how to create a pcb from start to finish.
![](555-pcb-done.jpg#center)
After placing and soldering all the components on my pcb, and applying power to it, I expected to see some nice flashing lights just like my breadboard model was doing. The first LED blinked on and off, the second blinked on.. and stayed on… Strange.
I double checked that the pcb matched the schematic – yep that is all correct. I turned on the circuit on the breadboard (I still have it on the breadboard as a working circuit when I created it) – and that was working. What could the problem be?
When showing off my excitement of designing my first pcb to an electrical engineering forum (EEVBlog) a kind soul (Hero999) pointed out that there was an error on my original schematic and that my circuit would not work.
After analyzing it a bit further I had come to the conclusion that I had failed to copy my breadboard layout to a schematic correctly. Because this was wrong, everything else was wrong. During this time I also must have altered the breadboard circuit without updating the schematic file.
![](FlashingLights.gif#center)
My original breadboard circuit was based on the one here and you can clearly see my schematic doesn’t follow this (R2 connects to +V instead of pin3).
Doh!
Learning to Fail
So what have I learnt from all this?
I was so worried about creating a perfect schematic -> pcb workflow that I didn’t spend enough time on the breadboard -> schematic step causing everything to fail.
So while I did fail – I also succeed as the pcb is a correct representation of the schematic – just that the schematic was all wrong.
I also need to pay more attention to ALL the steps in the workflow and not just focus on one step. Each step is important and can have a cascading effect if you get it wrong.
All is not lost though – the same kind soul on EEVBlog (Hero999) has also suggested that I can fix it by removing a solder joint and running a manual wire to the correct location. I’m going to give that a go the next time I’m doing some soldering.