Simple 555 Synth
2010
I'm starting a new project that will hopefully get me motivated to make some tracks. It's called 'One Instrument a Week', and it's exactly what it sounds like! I'll be building one simple music instrument or effect a week for the next year, and using them in my experimental Year of the Duck project.
Here's the first entry, a simple synth I built over a weekend based on a 555 timer IC. I used this schematic as a starting point:
I added a single 500K pot as a course pitch adjustment, and a board of resistors I pulled out of a toy piano to simulate some keys. I also converted the speaker output to a line-level output with a couple more resistors:
To play it, i have two probes from an old multimeter wired in line with the potentiometer. Touching the probes to opposite ends of something resistive (in this case, the resistor board contacts from the toy piano) cause changes in pitch.
Here it is in action:
Comments
Austin
Where did you add the 500k pot? This is exactly the kind of thing I'd like to build, and help would be appreciated. Thanks!
Tyler
If my experience with the 555 timer is correct, he replaced the 10K resistor with a 500K potentiometer. By the way, nice synthesizer, the 555 has so many great uses.
Dave
Thank you so much for the inspiration, I just finished my first synth!
zach
um do think it would be posible to utalise pin 5 and modulate the output for like a voice synth? using pin 5 as the audio input with a 470uf cap?
just a thought i made this circuit to its really fun to play with but befor i try this i want your opinion
pingosimon
Thanks for posting this! I made it on a breadboard and took a video! http://www.youtube.com/watch?v=FsF4qcFCzuo
Peter
I believe you just send the output (+) to one speaker connection and the the connection will come back to ground. If you are just setting this up to play with I wouldn't worry about which connector you use. You are just sending some pulses, so you don't have to worry about phase.
Peter
Sorry, mistype. I just meant to say that the OTHER speaker connection will come back to ground.
Martin
I have problem: Where I need to connect + of speaker and - of speaker??
Paul
Hi. Just want to confirm - the 500 pot replaced the 10k, and the set of keys? Where in the circuit do they sit?
Scott M.
It's been a little while since I made this, but yes I believe that's what I did. If I remember correctly the 10K resistor was replaced by the 500K pot and the keyboard connected in series, like this:
pin 7 -> 500K pot -> the black probe
And on the other side it looks like this:
pin 2 -> the red probe
The keyboard is just a bunch of resistors connected in series, and produces variable resistance based on whatever two points are touched. It's not actually wired in to anything. When two of the pads on the keyboard are connected with the probes, a circuit is completed and a tone produced.
When I get home today I'll put together a proper schematic that should make it easier to put this together.
Thanks for the interest!