Introducing Sprockit Mini-Synth

Sprockit Mini-Synth

Rockit’s getting a little brother, Sprockit. My goal with Sprockit it to take a lot of Rockit goodness and compress it down to something smaller and a bit cheaper. I’m achieving both goals by having a very dense design and by reducing some of the features. Sprockit is 4″x4″ versus Rockit’s 5.1″x8.6″, so it’s substantially smaller, like pocket sized (I would’ve called it Pockit Rockit, but there are some products out there already). There are obviously fewer knobs, LEDs, and switches. All of the control parameters are still there though and will be accessible via an external MIDI controller. The microcontroller is downsized from an ATMEGA644 to an ATMEGA328. I’m also incorporating a lot of the things that I’ve learned from doing Rockit and rolling those improvements into Sprockit. This image is my first prototype and I’m well into prototype two, which will be much improved. I’ll be doing a workshop with Dorkbot Chicago at the end of February where people can build Sprockit with me. I’ll probably do another Kickstarter project after that. I’ve learned from Rockit that I’ll need to get the case designed before I release it though. Click through for a complete feature rundown.Continue reading

Rockit 8 Bit Synth: Final Schematic and PCB

The Rockit 8 Bit Synth Schematic

I have ordered what I’m hoping will be the final PCB.  I’ve learned over the years that you never really know what you’ll discover once you build one up and hold it in your hands, but I’m very hopeful. I had to do this layout mostly to fix a few things. The schematic really hasn’t changed much in the last couple months.  Some values were adjusted but I like where things are right now in the hardware. 

From here on, it’s all software.  I’m working on developing more complex and interesting oscillator waveshapes, like morphing waveshapes and enveloped blended waveshapes.  They sound pretty cool.  I’ve also decided to add a last minute feature.  A lot of my friends have commented that they don’t necessarily have a MIDI controller but they’d like to buy one, so I’m adding a feature to make the unit kind of standalone.  I’m calling this a drone/loop feature.  Basically, I’m going to add a small sequencer. I’m not exactly sure how it will all work, but it should turn out pretty cool in the end since the Rockit makes pretty nifty droning sounds especially when you get the filter and the LFOs involved.  I was messing with this feature last night and I accidentally found an arpeggiation mode when the LFO is set to trigger the oscillator detune.  It sounded awesome, especially with some of the quirky new waveshapes I’ve added to the LFO.   Other than these new features, I’ll be fine tuning the software to get it ready for release.  I’ll be posting this project on Kickstarter after the new pcb comes in and I make a little video.  I’ve got some surprises for that, so stay tuned.  Here’s an image of the final PCB.

The Rockit 8 Bit Synth PCB

Rockit 8 Bit Synth: The Final Stretch

Rockit Silkscreen - Parts and Locations

I am so excited to announce that I am almost done. The hardware has been finalized. The circuit and all the values are a wrap. Everything is working: MIDI, filters, synthesis, LFOs, envelopes, Voltage-Controlled Amplifier, LEDs, buttons, patch save and recall… I’ve got the first pass of the pcb finished as shown in the silkscreen image above. I’ve gotten to the final knob locations and am pretty happy with that.  It’s been a journey but the final design should be on sale within the next couple months.  I’m looking at options for selling it from licensing it to doing it myself.  I might put up a project on Kickstarter. Stay tuned on that front. 

Things I still have to get done are mostly software tasks:  finalize pitch bend implementation, test filter audio in, flush out and finalize synthesis waveshapes, finish lfo waveshapes, and a few other small things.  Sometime soon after I check every connection on the pcb and optimize the layout, I’ll order some sample pcbs and build one up. In the meantime, I’ll be finishing the software. I’ve got some ideas for making more complex waveshapes, morphing sounds and such. At that point it’ll be done.  I’ll have to do some documentation, but I’ve been doing a lot of that through this blog.  So, expect the release soon. I can’t wait.

Make some quiet!

I’m making progress on testing the latest board and I got it making some noise. But, it’s not all the noise that I was looking for. It’s more!  Specifically, I made some layout choices that turn out to be quite poor.  Let me save you from making the same mistake.  Click through for the details.

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New PCB is in!

Rockit PCB

I got in the new pcb today and it looks great.  I’ll build it up tonight.  I have to recommend imagineering, the company that built the pcb.  They have an excellent first time offer of $25 a board. They delivered early and I picked them up this afternoon. I am excited! Let’s make some noise!

New PCB on Order


I’ve ordered what should be very nearly the final pcb.  There may be a few value changes and maybe a part or two in or out but I’m getting close to the end.  The plan at this point is to build up the boards when I get them in, then wrap up the software and call it a day.  Look for the project to be posted on when it’s finished.  I’m trying to go that route to get the funding to buy a run of enough parts to build 100 units.  Hopefully, that will get the ball rolling and I’ll be able to keep a continuous stock of units that will be sold here and elsewhere.  I haven’t decided what the final pricing will be, so stay tuned.  I plan on selling the units as kits and also as finished units.  In the beginning, they will be built by me, but eventually, I’ll get them manufactured.  It takes a good bit of scratch to get these things going so it’ll be a process.  This is all predicated on the hope that anyone will want what I’ve got.  I’m not even sure of that at this point, but one can hope, right?

I’ve also finally named the thing I’ve been calling the 8 Bit Synth for so long.  It will now be known as the Rockit 8 Bit Synth. Booyah!