Like a good little megalomaniac, I've recently become obsessed with extending my command of abstract software into the physical realm. To this end, I've put together some basic Arduino projects, and while this was really fun, it's operation remained mostly magic to me.
As legendary Physicist Richard Feynman put it:
What I cannot create, I do not understand.
To feel comfortable messing with digital electronics, I wanted to first have an understanding of the primitive units involved in their construction. So far I've progressed through most of an Analogue Electronics course available on Udemy. I managed to pick it up on sale for £10, a complete steal based on the quality of the course so far!
After covering some basic components it introduces you to an Integrated Circuit called the 555 timer. These cheap and tiny beauties can be used to output a voltage, oscillating at various frequencies. Something that's super useful for controlling motors, servos, and also creating audio signals.
I'd also caught wind of a tiny synth known by the name of the Atari Punk Console. And it seemed like a great opportunity to both practice circuit building and annoy the shit out of people with the harsh square waves it can generate.
Credit to Kaustic Machines for the circuit.
First, I have to muster the necessary components:
As it turns out the only potentiometers I had were 100k, and I'd only bought 555 timers (not the 556 that the original circuit at Kaustic Machines calls for). To stand a chance at building this I needed to adapt the circuit to work using the components I had on hand.
The 556 is essentially just two 555 IC's merged into a single chip so I could easily check the pins on the 556, and find where they would be on my 555s. However, those potentiometers were a little tougher to substitute. To find suitable alternatives, I needed to calculate and recreate the frequencies they're intended to drive through the 556 timer. Conveniently the details on how to make such calculations can be found on the 555's datasheet.
I tried to do this using a calculator but there were too many moving parts so I hashed out a tiny program to calculate it for me. After tinkering with the values, I managed to replicate the output pretty well by making the following substitutions:
It works! ...But smelt like smouldering electronics. In an effort to save my chips I quickly yanked the power supply and starting looking for the culprit.
After checking and re-checking the circuit on and off for a week, questioning the fabric of reality, and being filled with dread that I'm meddling with technology that I am not qualified to play with, I decided that the only way to proceed was to leave the circuit on so I could watch the fault catch fire and manifest as a burnt lump of carbon on my breadboard. For science!
After a minute or two, I saw smoke coming from... the potentiometer?! Turns out that the potentiometer's pins weren't making good contact with the pins of the breadboard and managing to burn it a little bit.
Now that I was slightly more confident about my abilities, I wanted to move the circuit from my breadboard and onto some perfboard which would be its permanent home.
During my first attempt of soldering onto this board, I learned several important soldering lessons. First and foremost you need to properly tin the soldering iron, that and lead-free solder sucks massive balls. Without proper heat transfer (due to the oxidisation on my soldering tip) the lead-free solder's melting point was too far out of reach.
After using a rotary tool equipped with a brass brush I removed the layer of oxides from my soldering tip, tinned it, then preceded to begin my second soldering attempt with some decent, flux cored, lead solder:
Finally, I imprisoned my creation in a cheeky little project box with help from a rotary tool and liberal amounts of hot glue. This would ensure a long and healthy life for the device, making it more resilient to short circuits, and look fucking legit.