This post combines some experiments I did over a few weeks, using a couple of different integrated circuit (IC) chips – the 555 timer and the CD40106.
01/02/16: I started playing around with the 555 chip after getting Forrest Mims’ Timer, Op Amp & Optoelectronic Circuits and Projects book, as I wanted to try making some small synths. Both the 555 and the CD40106 are good for creating simple oscillators, the pitch of which can be controlled using resistors and capacitors. In the video below, you can see how even touching these components can cause deviations in pitch.
18/02/16: After spending the past week gathering components and an enclosure, I started building the Toy Organ project from the aforementioned Mims book, which I decided would be my submission for Lab 04. The project is a simple synth that buzzes at different pitches when you press different buttons down. However, I had mixed success. On the breadboard, I was able to make the system work – I tried a few different capacitors, and they generated different tones. I tried implementing button control, although the effect was reversed: when I pressed the button down, the tone stopped. However, this was fixed when using a different type of button I had bought for the final result. When it came to soldering the circuit onto perf board, I had no luck. I tried it twice, with two different chips, on two different boards – but nothing. I think I need another pair of eyes to help me spot what’s going wrong.
Here are some examples I found of similar projects that can be achieved using the same 555 chip:
I also came across an interesting teardown of the 555, showing what exactly is in the chip and how it works in great detail. Check it out if you want more info!
The CD40106 is another great chip that is used a lot in Nicolas Collins’ seminal Handmade Electronic Music. Here is a great tutorial by Casper Electronics on how to make a simple synth using the CD40106, closely following Nicolas Collins’ book:
10/02/06: I started following the tutorial and playing around with a light dependent resistor to create a very simple controllable oscillator. Changing out the capacitor gives a different tone, so I bought a whole box of them to try! I definitely prefer the lower pitched ones…
I also came across an Instructable that shows you how to make an Atari Punk Console using a 556 chip (a 556 = two 555s). Definitely want to give this a shot!