This evening I found my self at a loose end and finally went into the pit of despair, or loft, and had a rummage for some 12V power bricks. Nothing AC but manage to scrounge 5 different 12V DC supplies that I could use to make a power supply with. I’ve got from 3.3A down to 0.5A here.
Normally I am a Kicad and PCB person but this evening I grabbed some strip board and just winged it. Sams influence has been rubbing off it seems. I drew on a few lines that will become busses for ±12v, ground and 5v and started a colour scheme based on what sharpies I have. Red +12v, blue -12V, 5V green and black ground.
I’ve also used what I have to hand, that’s mostly been knocking about for ages. This is why there isn’t an output connector yet as I don’t have anything suitable.
The “big” caps are 1000uF but only 10V so probably won’t last toooo long at 12-15V so I’ll need to grab some 20V+ caps. As they didn’t instantly blow I’ll just add something to my next Tayda order.
I also managed to let the smoke out for the first time in ages when checking the voltages some how. Blew one of the big caps, which got very hot.
To mount the jacks and switch I used an old cheap 1590B enclosure that’s been used for testing and practice so is full of holes, thankfully some happened to be in handy places.
The pink tape serves two purposes: it stops the board shorting out and covers all the dozens of holes. Also pink duct tape.
As well as being a bit of light evening entertainment it’s now the end of the excuse “I can’t build a VCO/sequencer/whatever as I can’t power it”. Need to order a 3340 or two now!
I know this probably won’t be the best supply ever but it gets me started and I can build something better once I source a 12V AC supply and I can do my own boards because then they can be purple. And purple makes every PCB better.
IDC connectors proved to be a pain. I’ve got a 16pin header and 10 pin plugs. Both places I ordered from had the same issue, so I’ll need to add some to my Tayda order I’m fleshing out.
I’ve replaced the filter caps with some 2200uF 16V so they won’t go pop.
The header was the “budget” one from bits box which was a mistake and I should have paid the extra few pence.
I also made (half of) my first power cable. I used a small vice I got in aldi ages ago to press into place.
Is there a “correct” way to route the cable. I’ve made it as below but it feels like I routed it backwards and the top is the strain relief that should have the ribbon hanging off that.
Hi,
Do not plug your headphones directly into your vco to hear it, it will be way too loud and there are some question of signal impedance if I am correct which could damage both your headphone and ears.
I used a small audio mixer 2 channels, to start, and it did the job just fine.
The bafaco output module looks like a good start. They also include the schematic so I can learn what out put should actually be doing vs just building something blindly not understanding anything. Looks like it drops about 60% of the signal through the first op amp!
edit: for reference I have neither a mixer or an interface at this point. I might get one of those Behringer USB mixers at some point, but an “output” feels smart.
Starting to get to a point where I’ll be building something soon so I guess I need to pick a format.
Kosmo: Pros:
More biggerer with more room for knobs and components on the boards.
PCB kits are affordable and generally don’t use expensive parts.
Cheap box, well in theory I’d need to goto the wood reclaim place. Have you seen the price of wood these days!?
Cons:
More biggerer so physically needs more space that is a premium right now.
It’s LMNC or DIY only for the most part.
Eurorack: Pros:
Common as a common thing so lots of options.
Smallerer so takes less room.
Lots of kits and pre made stuffs.
Cons:
Smallerer, often too smallerer.
Can be alarmingly spendy for reasons I can’t quite work out.
SMD isn’t fun for me, though would be an excuse to buy some new equipment.
Leaning towards eurorack mainly for space reasons but that may change when I do my own layout and it ends up at 32u wide once I use through hole and space stuff how I want them to be. So defeating the point of a smaller system. I do plan on DIY’ing for the most part, but I am sure I’ll buy some stuff on either system.
A great thing about Kosmo is it’s electrically the same* as Eurorack. That means a circuit designed for Eurorack can be used in Kosmo, and in fact with some ingenuity generally any Eurorack circuit board can be put behind a Kosmo front panel. You’ll probably have to leave off most if not all board mounted panel components and wire them, and that may leave you with a conundrum as to how to mount the PCB to the panel, but those are minor issues compared to converting between other formats with different power supply voltages, different signal standards, etc.
So when you see there are x hundred Eurorack PCBs on Thonk or Synthcube or whatever, you can think “x hundred Eurorack or Kosmo PCBs”.
You can also build both, and use them together. You just have to have some cable adapters or jumbler panels.
*There’s no 5V rail nor distributed CV or gate, but hardly any Eurorack modules use those anyway.
I had to pinch the Nano from another project so need to order a few really. Ideally with a more modern USB connector as it took a while to locate a USB mini, they must mostly be in the big box of cables in the loft.
The case is 3D printed will upload to somewhere shortly but obviously depends on what screen you have. Mine is 25mm wide and GVCD on the pins. I did plan to screw that in as well but realised a: the holes in the board are too small and b: it would pinch the ribbon so it’s just being supported by the case. Though this does make borrowing it for something else easier.
My only real complaint is that the screen is a bit close to the inputs which can make getting them out again a little awkward.
Anyway I have 4 more boards here, few marks in the solder mask which seems to be a common issue from JLC atm. Cover the post and an op amp or two and I’ll send you one of you fancy it.
I was psyched to print one of these and then I realized mine is built on a first run PCB, 1.5 mm shorter with no mounting holes and OLED header in the VGCD position!
This is showing it with a step file exported from the faceplace project added as a footprint to check alignments, and hole sizes etc.
Whilst it sounds complicated, it’s not as bad as it sounds and saves me worrying for weeks that it won’t fit.
Current state of the face plate. It won’t be ENIG, to expensive, but it helps show what will be plated in the final design. I need to change 1v/oct to CV as it’s not is it…
This might work for the space, not sure how well it will print but worth a go. Also a bit worked the name at the bottom is too detailed but unless I can think of a new “name” then that’s what I am stuck with.
I started breadboarding a 3340 vco and realised I had no way to attach the euro rack power. I have designed a PCB for it but I’ve not got 2-3 weeks for it to arrive so bodged one on some strip board.
I of course got both ground and +- 12v swapped so had to re do those again but now I have a quick way to power up the board whilst I test things.
I hope I didn’t damage my AS3340 with things backwards so I need to do some basic checks and see if anything is coming out of the outputs.
LEDs are offensively bright as it’s what I had to hand in blue and red and even with a 10K they are obnoxious. Probably should have gone in the 56k range.
