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 Time-Lapse Video

Check out this Rockit assembly time-lapse video! Big thanks to its maker, Siempre La Luna.


DIY Voltage-Controlled Amplifier

The purpose of the voltage controlled amplifier is to make an amplitude envelope like this.

When I started the Rockit 8 Bit Synth design, I thought that I could implement a voltage-controlled amplifier, VCA, in 8 Bit land, saving precious hardware and everything would be easy. Well, as with many of the other things that I learned in the process of developing this project, reality would not be so kind. In this post, I’ll explain why that doesn’t work and then fill you in on how you can implement a functional Voltage-Controlled Amplifier using some fairly simple hardware.
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Hackme Rockit: 8 Bit Synth Update

I can see the end.  The hardware is pretty much locked down.  I’ve got to do one final layout revision, but the circuit values and everything are more or less decided.  I made an ugly layout mistake in the last revision that coupled a lot of the serial communication into the audio signal as noise.  Only a new layout will fix that.

On the software side, I’m wrapping up the oscillators trying to get creative to expand the sonic palette. I’ll be able to continue working on the software until the end though.  So, I’m going to be starting the new layout this week and next, ordering the final board and winding this design down.  I’m really excited to get to this point, but often wrapping up all the loose ends can be the most challenging part.  I really want this to be as perfect as I can get it to be.

I’m figuring out how the final product will be made available.  I’m looking at some licensing options because I know what it’s like manufacture something and that’s honestly the least fun part of the process.  It’d be nice to license the design to someone else to build and sell so that I can design the next thing.  I’ll still support the design and make software improvements, maybe even a second version with some capability expansion, but it’d be nice if someone else handled the business end of it.  I’ll do it if I have to and it might be my only option.  I’ll fill you in as I know more.

Cheers and happy designing!

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!