After the last post I took a week or so to learn KiCad and faff about with PCB design, which was a very fun and interesting experience. It is a fantastic program! Since then I had been trying to get one section of the 32 Step working — the Step button.
You know how it is… everything works perfectly on breadboard and when you move on to veroboard things don’t go as planned. There are 3 main buttons on the sequencer which are Start/Stop, Step forward and Reset. The Step button, even though it was built exactly as it needed to be, would not work.
I figured the issue was the clock source (a simple 555 timer) but could not see any obvious problems; no dry joints, no dead components or shorts, nothing. I even made a separate timer on a breadboard and it was working perfectly with the Step button, and then made a new timer on veroboard and it was not working again…
In the end I discovered the problem was that the circuit needed an extra diode added to the 555 timer output. It is not an issue on breadboard but it is an issue on veroboard so it is all about capacitance I guess!
This was a really good lesson for me and it is another example of how important diodes actually are. They have been the solution to so many issues in the past. A lot of the time you need decoupling capacitors on veroboard too, even though you did not need them on the breadboard design. This makes the thought PCB design even more daunting!
Either way, now I can get back to finishing up the prototype.
Without any further issues I hope.
** Update **
Here is the new 555 timer added – everything working as it should!
(in the near future I am going to get a good camera as my phone camera is terrible)
mummica.com 