Thanks so much! Please drop your email here and I'll keep you updated with any next steps: https://tally.so/r/Y55dXv

Yes exactly, it would be great to be able to sync the clocks so they all ‘just work’ together. And maybe also a module that gives all the other synth parameters for the more advanced user too. I say it’s for my daughter, but I actually would love this too.

Im not sure youre aware of this but look up modular synthesizers. This is how electronic music was made starting in the 60s/70s

Would bent sheet metal have any sharp corners or edges? For kids it's probably best to avoid those.

The problem with music is you can't dabble. You need to dedicate half an hour per day for a few weeks before you reach the point where you are not terrible. You need years of dedicated practice before you can call yourself good. Finding that time is hard. Still making your own music is run and so I encourage you to press through.

Go grab a Teenage Engineering Pocket Operator, it's definitely worth a try ! I personally recommend the PO-33 (KO!), it is fun and easy to play with :)

There are also free software synths and DAWs available. GarageBand is the obvious one if you use macOS. I had lots of fun with that and with NanoStudio on iPad. I also own a Pocket Operator, which is fun and very mobile, but a bit pricey.

I've been messing around making a small web based project that does something similar if you're interested in trying a dabble: https://shantylab.com

If you want a synth you can buy that has a similar playing style, you could check out the Modern Sounds Pluto: https://www.modernsounds.co/pluto (the original run is sold out but you can find them on ebay/reverb)

It's two of these 4-note step sequencers with some fun timing randomness. Similar to the OP's synth it uses knobs to set pitches but the knobs are picking notes from a specific key so they always sound good together. It's a lot of fun to play and doesn't require any musical knowledge!

If the board is small (10x10cm or less) it will be almost completely free, like single-digit dollars, through somewhere like JLPCB. So I’d say don’t worry too much about that, just jump in and try!

As for actually designing, it’s a little more complicated than that but not by much. I did my first pcbs with KiCAD ~5 years ago by pretty much just guessing and googling where things were. Completely feasible if you have 0 background experience.

Hi, your mental model is essentially correct, though it took me a good few evenings over a couple of weeks to get the workflow down in fusion 360. The electronics retailer will usually have the footprint and 3d model available on the component page. You can then import it, define which pins you want connected to each other in the footprint and in the PCB editor you can drag the routes (wires) to connect them.

Printing is way cheaper than I initially thought it would be - I paid £35 or so, including delivery and 5 of them arrived in 5 days. You can get cheaper delivery though. Also most of that cost is shipping and the setup fee - the marginal cost for each additional PCB print in the order is on the order of low single digit dollars.

Tbh my circuit was fairly simple so I just took a bit of a chance (and some extra care wiring things up). I think there’s a subreddit where people give feedback though I haven’t submitted anything.

Depends on complexity. The article gives a price, for 5 PCBs which isn't unreasonable. However this was a simple PCB that used a lot more physical space than it would need to (for this application most of the space was needed because of the physical space the buttons/sliders needed so it was needed so this isn't a criticism). If you want to make a small PCB much more work is needed. This was a few analog sliders and buttons - no high speed digital data, if you are designing a computer (even Apple II level complexity) it is a lot harder. If you are designing a radio there are a lot of complexity. If you want to get this FCC (whatever your local government is) certified there is a lot more complexity.

This project is something that should be easy for someone with basic CAD experience. However many projects require a lot more complexity, so don't think that because most people could figure this PCB out in a day make you think anyone can do more complex PCBs, things get complex fast.

As a hobbyist, I have had a good experience using EasyEDA [0]. It's free to use, with the caveat that you are pretty locked in to their PCB ordering service from China. However, pricing is crazy good, like <$50 total for 5 PCB's (although there will be tariffs).

Regarding your mental model, it's more like a 2-step process. First, you draw the netlist, which is the electrical circuit diagram. It's this stage you ensure there are no short-circuits, etc. Then in the second stage, you drag-drop the components to the physical layout you want. The software then has an auto-router that references the netlist and automatically generates the first pass of PCB traces. You can tweak them if you wish. The EDA software also has a rules engine that checks for correct trace spacing, vias, etc.

For a "baby's first PCB", I bet you have more skills than you realize and I would encourage you to just give it a shot. Also, if you make a small mistake, you can manually "bodge" the board by cutting wrong traces with an exacto knife and/or soldering wires to the pads.

Everything else just comes from experience! If you're staying in the sub-kHz (audio) range, you probably won't need the crazy high-frequency tricks/trace capacitance/trace-length-matching concerns.

[0] https://easyeda.com/

jmb99 already said the part about cost/price. I just made a PCB for someone’s Halloween costume and it was only the 4th PCB I ever made. (So far I’ve used PCBWay for all 4 but since I’m in the US I also ended up doing a rush order from US-based Osh Park because I was panicking about how long the shipping was taking. Tariff situation has made shipping from China to the US more complicated. I found out DKRed, which is part of DigiKey, also makes PCBs in the US.)

For designing it I’d check out a kicad 9 tutorial playlist. You don’t need to know everything but it helps to know the right things, like how to run the design rules checker to make sure your PCB layout conforms to your schematic. There are a bunch to choose from but this one seems good: https://youtu.be/4YSZwcUSgJo

I haven’t done this but you can also try submitting your PCB design to /r/PrintedCircuitBoard subreddit for review, and they can also answer questions there.

For another data point: last week I ordered my first PCBs from JLCBCB. 2 fully assembled (parts already soldered) and 3 bare. $40 for the boards themselves, $40 for shipping, and $20 for US Tariffs, for total $100. Should take a week to arrive, shipping's cheaper if your willing to wait a month.

Re help: I asked for some help on libera ##electronics. I think there are larger communities on reddit that would also take a pass over designs.

My impression is that for straightforward circuits (not very high frequency or high power) you can get away with almost anything as far as layout goes. You punch in some generous setting for spacing of traces etc in the CAD software and it does some basic validation. (Are all the parts connected, not too close?).

I used KiCAD. It works well, though for assembly EasyEDA is probably lower friction. I had to dig around to find the right footprints for certain parts.

And then the things you do to redeem your guilt for the second child is a whole interesting area.

Don't assume: Could be an only child, or the spouse is stay-at-home, or the author has family wealth and doesn't need a full time job.

Thank you! Unfortunately I decided to save that feature for v2!

I have two of those. They are great additions to my drawers.

One has a silicon case and is nicer to use though.

Wood is also pretty child friendly.

But neither injection molding nor carpentry will protect a synth from a child dunking it in a puddle of water.

How are these, are they worth the money? I have seen these before, but thought they might be crappy "jokes". However, if they are decent, I would love to play around with them.

The answer to your question is "yes".

It is a synthesiser AND it is a step sequencer.

Both

A sequencer is always in steps. A synthesizer has a signal generator and can modulate a single step. This toy is both a synthesizer and a sequencer, but since you cannot toggle the 4 steps off, it will always be a sequencer in addition to the synthesizer

The linked project is both. A synth makes sounds, and a sequencer controls the sound over time usually with note on/off data. This sequencer has 4 steps before looping back to the beginning. To simplify, think of a sequencer as the music box drum and the synth as the tines in a music box.

A synthesizer is generally a higher-level ready-to-use product containing any number of oscillators, sequencers, and other circuits and bells and whistles under the hood. A device with an oscillator and a sequencer qualifies as a basic synth.

At a lower levels you find modules like sequencer, oscillator, etc. They are generally not used by themselves: you plug a sequencer into an oscillator to make use of it, just like a standalone oscillator by itself simply makes a continuous noise that gets old quickly. A synth does that connection for you and exposes the controls.

(To make things even more fun, the lines between lower-level audio modules are often blurred. For example, the difference between a sequencer and an oscillator can be best summed up as: the former is commonly designed for unipolar control rate signal change where you can specify exact level per step, while the latter is designed for bipolar audio rate signal change between two predetermined extremes—however, as the “designed for” hints, you could configure some sequencers to output a bipolar signal changing so fast it is audible, just like you could run a square wave oscillator so slowly that it becomes a 2-step sequencer.)

Thanks! Yes it's a little digital synth that receives MIDI.

I used Chroma Cap knobs: https://store.djtechtools.com/products/chroma-caps-knobs-and...

This sounds like a lesson I’m going to be learning the hard way

Mozzi (for Arduino) is also great!

https://sensorium.github.io/Mozzi/

Sanding and polishing, likely.

The surfaces you're seeing in the pictures are almost all the "bottom" surface that was printed directly on the build plate. It basically just picks up the texture of the build plate and is otherwise smooth. That's actually a fairly bumpy build plate they printed it on (which lots of people like for aesthetic reasons).

That said modern 3D printers are good at producing pretty nice parts these days, especially if you print with small layer heights. You might be underestimating the possible quality of 3d printed objects.

I trained as a classical guitarist, so I maintain some longer nails on my right hand :)

Reminded me of a BlipBlox…

https://blipblox.com

Agreed. That's half the reason that no matter how accurate a virtual synthesizer can be (like the Mac App Moog Model D), there's just no substitute for being able to physically fiddle the knobs and dials.

Same. It's a solid four-note ARP that sticks to a fixed set of musical keys. You literally can't make bad sounding music with this.

A more grown-up version of this would be 16 notes, with variable length patterns (4-16?), and a "swing" function. A little bit of I/O mux under the hood and I bet this design could be expanded in that way. Or maybe you just daisy-chain multiple sequencers?

Thanks for sharing!

I did some similar playing around with an ESP32 and I2S a few years ago (lockdowns were an odd time). Where I seem to remember getting stuck was how to get the phase to line up, so that each sample looped at a zero-crossing point (which is different for each frequency).

For the lazy, what did you do?

https://gitlab.com/afandian/melodicornamuse/-/blob/main/melo...

Lovely project and a really great idea.

Have you come across soft tooling for injection moulding? It's a lower cost, short run approach using much less durable moulds from various materials.

It’s a great project!

I’ve got some experience with small batch production and I’ve written an email. Check your spam!

One of my favorite kids music toy is a mini piano where you have to replay one among 5-6 melodies (each melody is 5-10 notes that you have to memorize by ear — no lights involved) to unlock a little happy sound. This toy managed to keep both, dad and kid busy for a while.

For anyone who likes the idea of better music "toys" for their kids (i.e. not toys at all, but still easy to use) but doesn't have the capacity to build stuff like this, my kids and I love the Korg Koassilator: https://www.korg.com/us/products/dj/kaossilator2/

You can usually get them on eBay for USD$60 - 70. You do need to bring your own speakers, but a pair of cheap PC speakers are good enough, and it's a good start on creating a whole synth + effects chain.

Speaking of which, there is also the Mini Kaos Pad, which is a dynamic effects processor: https://www.korg.com/us/products/dj/mini_kaoss_pad2/

This one is a little more difficult to figure out for the kids as it is a "modifier" in the chain and they haven't quite wrapped their head around that concept yet. But still, it works great, has lots of features, and is really inexpensive for such a thing.

And finally, they have a number of these mini-synths that are in the USD$30 - 50 range that are a ton of fun: https://www.korg.com/us/products/dj/monotron_duo/