Moving forward with the secret knock in a box

A few months ago I made a box with a secret knock in it for an interview for a school project:

box with a secret knock in it. from nikkipugh on Vimeo.

It’s proved to be very popular, so it’s time to take it out of its prototyping stage and into something a bit more robust.

The version I’ve been using so far runs off a Real Bare Bones Board mounted on a breadboard. It’s OK, but I need to keep checking it all the time to make sure the wires haven’t come out. Not ideal if you’ve got a dozen young children clamouring around to try and guess the hidden knock!

I could move it to perfboard or something similar, but I suspect I’m going to be making several of these in the future, so I’m using it as a project to learn a bit about making Printed Circuit Boards (PCBs).

The first stage has been to eliminate the RBBB and move to a freestanding chip. I followed the approach on the Standalone Arduino / ATMega chip on breadboard Instructable.

I then combined this with the power supply from this ITP tutorial on breadboarding an Arduino. And finally added all the switches and gubbins from the original circuit.

Freestanding ATMEGA with additional project circuitry

It worked!

…and was a nice bit of learning too – I feel all empowered now!

Putting it all together. With arrows.

Having ascertained that it wasn’t all going to go fizz or POP, the next stage is to start arranging all the bits into a nice PCB layout.

…And for me to profusely thank Dr Sugden and the Eng Soc students at Aston University who are proving to be top notch fizzPOP collaborators and walked me through this afternoon’s learning. Much appreciated.

What’s next?!