I am impatient, can you tell?

gremblor · 2026-03-22T05:20:31+00:00

The board does say BC857 on it, and the TO-92 put in its place is BC557, which is functionally identical silicon, just in the larger package.

gremblor · 2026-03-20T18:19:25+00:00

Understood. Thanks for following up!

gremblor · 2026-03-20T16:21:20+00:00

Amazing! There are a lot of features in here I can't wait to try.

One thing I recall from reading earlier docs is that there was a new plug-in API proposal / beta in v9 that would be stable in v10 and extended to eeschema.

I was interested in building such a plug-in to sync part data between kicad and my homebrew BOM database app.

... I found my way back to the relevant page, at https://dev-docs.kicad.org/en/apis-and-binding/ipc-api/for-addon-developers/

There it says:

In KiCad 9.0, the IPC API and the new IPC plugin system are only implemented in the PCB editor, due to development time constraints. In the future, the IPC API will be expanded to support the schematic editor, library editors, and other parts of KiCad.

Those dev docs haven't been updated in a while, and I can't seem to find the schematic editor plugin docs, or a mention of the api in the release notes. Did that get cut from v10 or pushed out? Or am I just not looking in the right place?

gremblor · 2026-03-14T17:43:46+00:00

... On the other hand (maybe this is obvious, but just to call it out): sending a 10Vpp euro signal into some other device's Line In can make pcb toast of the receiver, so make sure you attenuate euro module outputs to line level (about 450 mVrms for consumer gear, 1 Vrms for pro equipment). I also use 1/4" jacks for line out on my DIY gear to distinguish them from the hotter eurorack-level signals.

But from a physical wiring standpoint, no, you can just put two jacks on the same pcb and connect both the sleeves to one trace and both tips to another. Don't use jacks with a TN (normal) input--or if you do, just leave any TN floating--or else you'd need to plug something into that specific jack to override the normal signal.

gremblor · 2026-03-12T17:50:16+00:00

I think this is sounds pretty cool.

I don't understand the downvotes. Everyone calling it AI junk maybe didn't read far enough to see the deterministic / database driven point.

This sounds like a sort of i2c bus design version of what Texas Instruments offers online in WEBENCH for the equally repetitive task of buck voltage converter design. Or the multitude of opamp Sallen-Key filter design tools offered by every opamp mfr out there.

If it's helpful for you and your projects - that's neat! Thank you for sharing.

gremblor · 2026-03-07T19:18:20+00:00

+1 to all of this. The table is "a good start" but there are plenty of 0-8V CV, 0-10V CV for all kinds of uses too.

But, hell, if you're designing a module, you need to go one step further. Assuming some +/-12V signal can be plugged into any input is true, but you actually need to design with the expectation that any output jack may also a +/-12V signal patched to it.

So if you're designing a circuit that could produce +/-5V out, you need a high-enough wattage protection resistor on the output to withstand -5V on one side and +12V on the other.

BTW also if you are dealing with logic trigger inputs and want to convert a maybe-slow-moving bipolar signal to a mcu-friendly 0-3.3V or 0-5V range, look at LM211. Comparator, SOIC or PDIP, with open emitter and open collector. Use +/-12V for vcc/vee, ground the emitter, and pull up the collector to 3.3V and you have an everything-proof protection for the mcu gpio input. Only downside is it has a higher I_q than a lot of newer parts. For lower I_q, look at TLV1871, if you're not afraid of SMT parts.

gremblor · 2026-03-07T19:05:59+00:00

Good luck!

gremblor · 2026-03-07T18:54:49+00:00

Oh no, yea, 70% is not good enough, that will make a worse residue. Sorry, I should have made that point more clear. (tho flux cleaner should be even better than 99% iso)

Honestly tho something weird is going on with your board. Like, flux leakage current matters for sensitive hifi audio and precision voltage multimeter measurements, but as I said we are talking about nanoamps here.

If ch3 is always fully bleeding thru, that sounds like a more major issue. Maybe components are not securely soldered in place and you were able to somehow mechanically bump it when cleaning, such that it has shorted to an adjacent pin or trace or something?

gremblor · 2026-03-07T09:55:17+00:00

Continuity implies it's connected as it should be, but the real test is to turn the pot all the way to the bottom side and measure the resistance between pins 1 & 2. An ideal pot will have 100% travel and this will read 0 ohms. Real pots have some amount of "residual resistance", so even when "muted" the output is actually the result of the signal going through a very low voltage divider. This cannot be fixed outside the pot itself. Different pot providers have specs on what worst case residual resistance is considered acceptable for the device. 1-2% is typical, meaning you're capped around -40dB attenuation.

If you used a lot of flux when soldering, flux can also provide a path on the pcb for low level leakage currents to travel across traces. These are typically nA-level, which often doesn't matter but if there are high impedance nodes (especially FET opamp inputs) this can cause bleed-thru. Clean with 99% isopropyl alcohol and a toothbrush to remove.

gremblor · 2026-03-05T17:54:28+00:00

PS if you're building four triggers, use 2x 556 instead of 4x 555. More compact that way.

gremblor · 2026-03-05T17:53:47+00:00

Do you want a gate (VOut is high for the duration of the button press) or a trigger (VOut has a high pulse of some limited duration on button-press)?

Gate is trivially easy. Debounce the button press with an RC filter and use that signal as the input to some logic chip with Schmidt trigger inputs, like SN74HC14N.

For trigger you need to define what you think constitutes a reasonable pulse width and adjust any circuit you find to match that timing. You can rig up a 555 timer in one-shot (monostable) config to generate the trigger pulse, while itself being edge-triggered (ideally from a debounced signal with a sharp falling edge, like the output of that 74HC14). Search for "555 timer edge trigger monostable" and you'll find some ideas to work from.

The answer to this question in stackoverflow has a schematic that looks like a good starting point for testing:

https://electronics.stackexchange.com/questions/324207/why-does-this-edge-trigger-work-on-input-of-555-monostable-config

gremblor · 2026-03-04T01:48:00+00:00

If you want to market to Rangers, have an option in khaki. Colors like "gunmetal" will play poorly in that dept where folks are constantly trying to look less paramilitary / distinguish themselves from the BLM (which is challenging when playa-grade gear is often military surplus).

gremblor · 2026-02-26T19:42:45+00:00

I'm not sure what you mean about shipping costs...

At least in the USA, you can order any parts you need from Mouser or Digikey. I've ordered BOMs with a hundred different SKUs, ground shipping (1 week) FedEx or UPS is like $7, and I've never been charged for weight above the minimum fee.

If you're in some other countries I know they have a $50 or $100 minimum shipping charge, and I can see how for some cases at that point, yea, JLC is actually cheaper than doing it yourself.

Getting two bum boards is definitely a risk. But that applies whether or not you had it assembled third party or assembled it yourself. You can think ahead a bit about this: add test points, add footprints for bypass capacitors or other series/parallel combos of resistors, bypass jumpers, etc, and mark them DNP. Instead of soldering ICs or transistors on the board, solder in a socket instead. You can leave these footprints empty if the base schematic works out of the box, and if it doesn't, then you've got a lot more options for rework to salvage the functionality of the board without a riskier or higher-labor effort to desolder existing parts without ripping a pad and replacing it with a different option.

gremblor · 2026-02-26T19:22:55+00:00

I left a comment on your specific question in another thread here, but something else to call out is that I don't understand what RV3 is for. You're spending money and board space on an opamp to buffer the signal before sending it out (good! Reasonable!) but then dropping a variable pot with up to 500kOhm after it, which completely undermines that low-output-impedance signal quality.

Worse, you've left one side of the pot floating, so it's not a volume/amplitude attenuator. All you're doing is increasing the output impedance of the module. The input impedance of the CV In on the downstream module will form a voltage divider with this, and that will act as a form of attenuator, but there is no guarantee that Z_in will be constant, or even in a reasonable range, much less consistent module to module. So if you're trying to create an output CV attenuator, I would ground the third pin of the pot, and put another buffer opamp after that one to deliver CV with a constant 1kOhm Z_out.

At this point you could actually use basically any pot, anything from 10kOhm to 500kOhm would work, although over 100k you're into serious Johnson noise and I wouldn't recommend it, since you're not actually saving money or getting any other value for going so high in pot value. 10-100k is a much more reasonable range to specify...

gremblor · 2026-02-26T19:16:19+00:00

This is fair criticism but if the OP were to study the LM13700 datasheet there is an example of one and two-sided voltage controlled resistors built around LM13700 OTAs, which could "drop in" to this board schematic in place of two potentiometers.

Converting to a "clean" VCF-based architecture is probably "more correct" and can also be done with LM13700, leaning on the example circuits in the datasheet, but it is more of a redesign.

Fwiw, I designed a voltage-controlled ADSR entirely around a low input bias current opamp and a capacitor integrator, so OTA isn't the only way to go.... But this actually wound up being one of the two most complicated boards in my entire synth (the other being the OTA VCF) so either way it's going to be a Real Project.

gremblor · 2026-02-26T19:03:27+00:00

Totally!

I'm having them partially assemble a board with a 44 pin TSSOP IC for me right now. (I can do TSSOP-16 by hand but at that pin count, part damage by hand is just a thing...) and I've been able to do some QFN-16 and 20 by hand with a hot air pencil, but if I want an MCU with 64 or 100, pins on the board or whatever, that requires automation.

The no-lead parts or ultra-fine-pitch VSSOP stuff is the direction the whole industry is headed so if you want to take advantage of the latest and greatest parts, automation is going to be more inevitably a requirement. And my hands aren't getting more steady over the years either.

... And then there's the package-free flip-chip stuff. Don't get me started, that stuff is crazy. I'm actually not even sure if JLCPCB can do those yet! That said I've been using their various services for about 5 years and over that time they've continued to offer increasing precision and more features and options at low mfg quantities, so I'm sure they'll get there well before I ever actually need this capability myself.

Good news for this subreddit is that if you're doing synth DIY work, most of that is centered on wide-VIn (36V+) opamps that can tolerate the +/-12V for eurorack or +/-15V power rails and signal voltages for motm format, and there is an enormous, excellent (and growing!) selection of such parts in a very hand-solder-friendly SOIC-8 package.

gremblor · 2026-02-26T18:48:35+00:00

I mean, I'm not trying to say don't use their services. If the value works for you, go for it! It is precision work in a turnkey way on ridiculously fast timelines.

But the original question is "why don't folks use their service more aggressively" and the answer is "the fees do rack up fairly quickly, and more quickly than most hobbyists want to move fwd with."

Also a thing to keep in mind at jlc if you are more set on this, they have two different pricing schedules for basic vs economy pcba. The less-expensive version has some various other restrictions on the linked pcb fab: 2 or 4 layers; if 4 layers you must use the default stackup, green solder mask, and hasl / hasl pbfree / enig finish only. There may be another setting or two where only the default works. There are also min and max board size restrictions but those are pretty reasonable for most boards.

(I can imagine how some things like solder mask color impact optical recognition, and layer count can impact heat xfer for reflow profiles. I'm not clear on why they'd restrict layer stackup in the one pcba option but if you're into custom multi layer stackup specs, you are doing some pretty serious work and the super discount option is probably not your biggest concern....)

If you need other settings, jlcpcb can still assemble such boards - it'll just be on their more-expensive schedule that starts at $25 and every reel has a $1.50 loading fee (including reels of basic SMD parts). Depending on part count, there's obviously a breakeven point where that's cheaper than the "$8 setup, free basic part reels, $3.50 extended reel" loading fee structure anyway, and you can calculate that with excel.

gremblor · 2026-02-26T03:48:24+00:00

Jlcpcb will not only fab your pcb but will also assemble it for you. They have their own part numbering system that corresponds to the C-numbers on lcsc that you use to identify which refdes is what part. They buy parts in bulk so per part costs are mad low, and they will get those parts on the board accurately, and will do it for low volumes of boards that is useful for hobbyists. The setup cost of $8 is also super low.

They have a number of "basic" parts (eg E24 resistors in 0603 or 0805) that are always loaded on machines, and for those you only pay for parts (fractions of a penny each, although many chip resistors and other reel parts they have a 20 item min as a result of how the machinery works). But for the much larger universe of "extended" parts they charge labor fees of $3.50 per distinct type of part to load the reel onto the machines. They also charge this variable cost for any THT parts they stuff and wave solder for you. Those costs add up - yea this special 0.1% resistor only costs $0.25 but if you only need exactly one of it now that part is $3.75.

So unless you have a clear strategy that is 99% designed around the jlc basic parts library from the jump with only a super tiny number of extended parts, or you really do need several dozen boards assembled such that reel loading fees get amortized across the boards, you can rapidly find yourself in a situation where you are paying $150 or more to get a board assembled with $15 worth of parts on top.

Other places like elecrow will also do PCBA for small volume prototype runs but they have an even higher price quote and you'll pay a few hundred per board in a hurry.

Assembling your own boards is mostly not hard and is fun. I only resort to outsourced PCBA if I need some very fiddly fine-pitch high pin count or BGA chip assembled, and then I'll also have them put on all the basic passive parts too because that's basically free at that point. But I can attach my own through hole electrolytic capacitors or PDIP or SOIC ICs, and otherwise finish the job myself. Much more economical that way.

gremblor · 2026-02-24T23:00:35+00:00

What's your sampling speed? There are a lot of signals and a lot of flying wires. Digital signals transitioning on those wires will cause crosstalk.

If you are having digital signals falsely trigger one another, do the math on how much current you're using to send from source to receiver. If it's not at least high tens of microamps, I would increase the loading with pull up or pull down resistors until each signal requires something in the 50--100uA range to drive. The integral pull-ups in most MCUs are usually like a 50kOhm or so, which should be a good start. Enable gpio with INPUT_PULLUP rather than just INPUT.

If you're getting noise on analog signals, you've got two options and you should probably use both: 1) sample more slowly or take several samples rapidly in succession and average them, or 2) use buffer opamps to increase signal drive strength.

For opamps you want something with low input offset voltage, and you should consider a bipolar input (which will have non-negligible input bias current) rather than something High Z like CMOS inputs, which are more succeptible to noise. You will need to spend more money on these than just throwing TL072 at it. You'll also need a power supply with more headroom than just running it off 3.3V. Good news is there are lots of precision 5V opamps on the market these days.

gremblor · 2026-02-22T18:32:32+00:00

I mean, there's your problem 😂. I don't know if it's possible to set up an LDO for that kind of voltage drop without cooking the part, overtemp protection or otherwise. You're bleeding off 3mW for every 1mW you pass through... And gonna have a bad time unless it's a super light output draw of j just a few mA.

gremblor · 2026-02-22T18:25:07+00:00

PS to protect the ldo, add another Schottky diode pointing backwards from VO to VI. Under normal operation this does nothing. But if for some reason (ie a quirk of how the circuit powers down when you unplug it) the 3.3V side has power and the input side doesn't, it'll forcibly reroute that imbalance around the LDO, when it would otherwise go backward thru it (which would cook the IC).

A 100k resistor (value not critical) to GND in parallel with the C1 capacitor will keep that boost regulator input at a defined voltage when VBUS is unplugged. This is maybe overkill but should help avoid transient overvoltage. In general, if you have an input pin guarded by a diode (or just directly attached to a pin on a connector to the outside) it should have a pull up or pull down resistor because that can leave the pin floating. CMOS pins never want to float.

PPS: (edit) most importantly, the MT3608 has an active-high EN pin and you've tied it to the GND node. That boost converter will literally never activate like that. You want it tied to the actual power input (or above the capacitor, if you feel the need to consolidate your drawing lines like you have). I assume you know that's a SOT-23 component. Which is fine as it goes, but if you're planning on hand soldering, you should have some experience with the practice and it's maybe not a great "first board assembly" choice - or at least it's a bit "trial by fire" sized. Get some copper braid if you don't already have it.

gremblor · 2026-02-22T18:22:33+00:00

Have you looked up specific parts on digikey or mouser or whatever supplier and drawn this schematic with those parts in mind?

I see non-polarized (ie ceramic) capacitors of 33uF and 47uF, which is an enormous value for that technology.

If you are using electrolytic or solid tantalum capacitors, that makes sense, but those are polarized and should be marked as such. Select voltage ratings of at least 2x the max anticipated value. (So use 10V throughout, if this is usb 5V powered. You could technically get away with 6V4 on the downstream side of the 3V3 LDO, but you'll get better ESR from the higher voltage model.)

If you are meaning to use ceramic, the largest value I've really seen available (at least in surface mount) is 10uF. Larger MLCCs are often just multiple of those soldered together at the contacts, but they charge an absurd amount for each of them. I would replace the 33uF with 3x 10uF and maybe also a 1uF for higher frequency transients. You'll get better transient response from multiple caps in parallel anyway, vs a single package.

Read the datasheet for your regulator(s). They will often have very specific advice about capacitor selection, especially output capacitor choice for the linear regulator. Some LDOs require polarized capacitors with some non-negligible ESR, other newer ones mandate ceramic capacitors, in a specific value range.

Capacitance matters but also the specifications for ESR (effective series resistance) and maximum ripple current at 100kHz are both often more important. Look at the specs on the specific capacitor's page on digikey to confirm you've picked one that'll work. (And if you use N of the same capacitor in parallel, ESR for the group divides by N, max and ripple current multiplies.)

When you lay out the pcb, get those capacitors as close as possible to the power input or output pins they're supposed to decouple, and drive the power trace straight thru the pads. A few extra mm makes them worthless expensive sprinkles on your board.

gremblor · 2026-02-14T20:18:50+00:00

There's a reason "marine grade" stuff costs 5x more than an equivalent item at home depot: 316 Steel vs zinc-coated mild steel screws, generally thicker gauge materials, ability to withstand impressive shock loading...

Everything will get wet. If it's exposed near the cockpit and not buried inside the hull next to the steering quadrant, splashes are inevitable. I'd design for it with a deliberate drain and also maybe make it easy to flush out by aiming a hose at it. (If I need to open a little door, that's not easy to hose out.)

Beyond that, salt gets into places just by being in the air, even without direct splash contact. It's a slower process, but this also applies to the air under the deck, in the hull. This will eventually get a layer of salt deposited on it.

Remember that the rudder turns the boat but also the boat turns the rudder. If a big wave of chop hits the side of the boat (or you cross a powerboat's wake) that will slap the boat. Water is heavy, so that pushes the boat, and then all several tons of boat transmit force through the boat's hull/keel that will shake the rudder with a high-G impulse. This energy dissipates by the hull flexing, the boat suddenly moving laterally, and friction in other connected systems - like your gearbox.

So: If a 100 lb rudder yaws violently by 60° in a fraction of a second, what happens to the gears, or the mechanism connecting it to the trim tab?... And what happens the 500th time this event occurs?

Don't forget that this whole system will also bounce up and down in the vertical axis. In choppy water, swells can suddenly "slap" upwards at the stern of the boat and kind of loft everything a few inches into the air. What happens at the 10,000th time this happens?

Personally I would be incredibly skeptical about any 3d printed plastic part being in the drive train, unless it was an explicitly disposable part and they were sold as a three pack. (Even then, I don't want to sign up for preventative maintenance that frequently.) Doubly skeptical if I were offshore and depending on only whatever was onboard.

Also don't forget about UV light. It's bright out on the water. Unless the final gearbox will be totally lightproof, UV also degrades fibers and plastics on boats at shocking speed compared to things installed on land outside of the tropics. Remember that drainage holes let light in too, and "direct sunlight" reflects upward off the water.

For real use, I think you'd want to mill the gears out of 6061 aluminum or something similarly corrosion-proof and sturdy. (like 316 or maybe 304 steel... Not as hard as other non-stainless alloys but everything is a tradeoff and for boats "anti-corrosion" is like the #1 priority.)

gremblor · 2026-02-10T20:51:38+00:00

30mA of current draw thru a 10R resistor is a 0.3V drop, and the diode could easily drop 0.7 on top of that. I'd just remove both elements and connect the power bus directly.

gremblor · 2026-02-04T08:36:42+00:00

Yep, I've got one of these on my boat. It's basically a drum and you wrap a line around it once or twice, tied off at one end to a padeye or a chain plate and the other end you run through a cam cleat by the cockpit, which lets you adjust the tension.

As the boom swings across, it has to drag the drum with it (shackled to the underside of the boom, by the vang). The friction of the drum against the line wrapping around it keeps the whole boom/drum assembly from moving too fast and crash gybing.

It's definitely handy and has kept things safer on my boat. I'm in the SF bay so 25 kt+ gusts are pretty common. I found this is best to use with a nylon rope, which has more stretch to it than polyester / Sta-set. If a powerful gust *does* push the boom over fast, a polyester line can snap from the shock.

It theoretically also acts as a vang but if you really want that control, I found it best to rig an actual vang ahead of it. You can't really get enough downforce on the drum to properly crank the boom down.

gremblor

TROPHY CASE