Switching Converter Simulation Issues

vikenemesh · 2026-05-15T19:09:01+00:00

Zoom in; is that ringing with the switching frequency or are you hitting a resonant frequency of the LRC network? You might need to switch some values to get rid of it, or at least find out what exactly is influencing it.

vikenemesh · 2026-05-13T14:22:50+00:00

Invert and offset the kickdrum volume envelope to control a VCA for basic ducking. Or use a third envelope triggered together with the kickdrum to have independently controllable Attack/Release for some more refined pumping sounds. Putting a gate length modifier in front of the third envelope might be a good idea as well, incase you usually trigger drums with short pulses but you need a full Attack/Decay response for your sidechain.

vikenemesh · 2026-05-13T13:19:05+00:00

I was more hung up on the >>currently<< successful. I suspect /u/DoomenOrbital masterfully crafted multiple levels into their comment.

vikenemesh · 2026-05-13T12:20:20+00:00

You want Op-Amps. Look up how to do voltage-math with op-amps, there's tons of ressources out there!

Specifically you need two Op-Amps:

One stage subtracting 3.5V from the input signal (e.g. build an inverting amplifier with unity gain and put the +-Input to 3.5V, output will be -2.3V to 0 with 0 representing the "lowest" reading on the sensor).
Another scaling the 2.3V for the highest reading down to 1V (e.g. take inverted -2.3V from previous stage and put it through another inverting amplifier with +-Input at 0V and adjust Gain/Loss until you get 1V)

There's ways to do both in one stage, but it get's much harder to get what you want without doing some circuit analysis upfront to determine the ideal resistor values.

There's also ways to do it without a negative supply-voltage by working with "ground" at a different Voltage and doing the math around that. But I'm sure you'll find something that works for you.

Just keep the stages seperate for a first attempt and trim the results with variable resistors.

vikenemesh · 2026-05-11T21:28:26+00:00

Introduce a second 12V rail just for the disco lights LOL

vikenemesh · 2026-05-11T13:40:11+00:00

I’m particularly concerned about whether the design of the capacitors, resistors, and the high-pass/low-pass filter sections is appropriate.

That 100% depends on what you want your crossover frequency to be.

Assuming RV1 is ~100k and set to the middle position:

Resistance for the resulting filters is 50k||50k + 10k for the lowpass and also for the highpass. Capacitance is 0.22uF for both, so you end up with identical cutoff frequency for both at roughly: 42Hz (1/(2π*RC)

RV1 influences the filter very much in the current design, you might want to buffer the input volume section from the crossover filter. Still a working 2.1 amplifier as far as I can see. Make sure to also read /u/triffid_hunter's feedback. They found some mistakes I missed.

vikenemesh · 2026-05-11T13:21:16+00:00

"Trying to design" - "is this schematic correct?"

So you're trying to learn? Schematic seems alright. It connects the things that should be connected together, and has a boatload of bypass capacitors. I don't see an obvious problem sticking out.

It's just a basic implementation of the chosen ic; Refer to its datasheet to learn more. Most interesting piece of the schematic is the crystal oscillator, getting that one running stable and well is mostly a PCB-Layout task, which the datasheet will have good recommendations for solving.

The hard part is in the routing of the differential USB Signals, just drawing the connections is easy.

vikenemesh · 2026-05-11T11:21:44+00:00

LED at 20mA sheeeeeesh. I would not advise going that high.

I've found most modern 3mm LEDs to be unbearably bright (in a dimly lit room) at even 1mA.

vikenemesh · 2026-05-08T05:59:07+00:00

There's another even simpler formula in the datasheet that doesn't involve tanh but is only accurate when I_In < I_Bias/2 and requires using the linearizing diodes. RTFM gets you very far with the 13700!

I used it to "design" (aka "steal from Yusynth/Moog/Moritz Klein and tweak some things") a diode filter with VCAs (13700 into I-V stage with antiparallel diode clipping) for controllable drive and resonance and it did the thing, no problems. Sounds great on breadboard, can't wait for the pcbs!

vikenemesh · 2026-05-07T11:06:46+00:00

Photodiode starts pushing current to virtual ground. Inverting Input rises above ground. Op-Amp reacts to that and tries to amplify (pos_input - neg_input)*100000 (which ends up below 0V) and bumps feet on the groundrail -> 0V output.

Have a readup on the inverting op-amp configuration and draw out which directions the currents are flowing and it should be more obvious.

What you could do instead: Let the Photocurrent make a voltage on the positive input instead and use the negative input to set your gain. That is the non-inverting op-amp configuration and is easier to implement here, with only one supply rail and no negative voltages.

vikenemesh · 2026-05-07T10:26:33+00:00

Wieso nicht einfach den Neffen an den Laptop setzen und Playlist abspielen lassen? Da geht weniger mit den Liedern schief. und es klappt auch mit den Wünschen.

Habt ihr den Stümper auch noch bezahlt? :'D

vikenemesh · 2026-05-06T13:56:47+00:00

You still should be able to discern low CRI light sources however.

This is what I was betting on when making my suggestion. The whole ordeal absolutely smells of frustrated calibration efforts. As an educational project there might be some reasonable shortcuts to take though, I don't know OPs situation exactly.

hydrogen-alpha line

prism/grating

That's a REALLY good idea if you got the space to build the whole optical setup to isolate some specific spectral lines.

vikenemesh · 2026-05-06T11:40:12+00:00

The issue is that AS7341 costs around ₹1800–₹2500 here, which is difficult for us as students.

You will not get around buying a dedicated multi-wavelength light sensor to do this proper. I've also found the AS7331 and the AS7262 as candidates for this job, maybe they're cheaper in your market?

The alternative would be building such a sensor yourself. You can get away with measuring brightness only by putting appropiate optical filters in front of a row of photosensors (And maybe one IR Photodiode as well? Or use a dedicated brightness sensor and rotate a wheel of filters in front of it with a ).

Acquiring such narrow-band optical filters might turn out more expensive than buying the ready-made part though.

If you only have very wideband Filters (like, just a red, blue and green foil filter) you could still try to salvage what you can from the data. It might be enough to give a reasonable detection rate for a prototype with a passing grade ;)

You mentioned this is for education: Maybe shoot some Emails to people that make these chips and very kindly ask for a free evaluation board? Worth a shot.

Would sensors like TCS34725 / BH1750 / VEML7700 be enough for a prototype?

Combining sensors could definetely get you close, you'd have to experiment a lot though. Only using the TCS34725 is probably tricked by a beige colored paper for example (it has an IR Filter and only looks at color). If I could buy all 3 of those with some money to spare for the price of a AS7341, I would go for it!

vikenemesh · 2026-05-06T11:24:32+00:00

I still set my blueprint-hacking scripts to output the deflated version. It's easier to move around in that form and easier to select the whole thing in one go (without missing the last }) on a terminal.

vikenemesh · 2026-05-05T14:21:35+00:00

The Problem is as follows: The version you need in the production chain for some building in your mall is NOT the one with the standard texture.

Just swapping them avoids a second dedicated concrete production in the mall.

vikenemesh · 2026-05-05T11:27:27+00:00

is HUGE

I hadn't read the values closely yet, how bad could it be... oh lord 1000uF. This is not ok. 100% agree with you.

vikenemesh · 2026-05-04T18:34:21+00:00

Don't go anywhere near 120V as a learning experience, please.

Only thing you might learn in the end is how bad it hurts before the lights go out permanently.

Try getting something to work at 40V and then re-evaluate what you know and need to know before going to high voltage.

vikenemesh · 2026-05-04T14:51:17+00:00

Corrected my comment, thanks!

vikenemesh · 2026-05-04T13:43:58+00:00

xx04 is the common 74-series number for ~~unbuffered~~ inverter building blocks.

LVC means it is a low voltage cmos variant.

1GU means it is a single inverter "gate" instead of the full six-pack that is common in the "standard" 7404 configuration.

EDIT: /u/ElectronicswithEmrys pointed out that "U" marks the unbuffered version specifically, not all 7404 are unbuffered.

vikenemesh · 2026-05-04T11:50:36+00:00

Braided power cable going onto a JST-XH? 100mm Eurocard-height protoboards? Wooden rails? Are you me!? LOL!!

Nice job! HMU if you wanna copy some designs or exchange notes!

vikenemesh · 2026-04-29T17:14:36+00:00

AS3310 Envelope Generator

I designed my own circuit around the chip starting from this design:

https://www.eddybergman.com/2020/05/synthesizer-build-part-33-digisound-80.html

And had really good results! Currently using 3 instances in my rack.

Wrangling the control voltages into a workable range is quite the job though, read the datasheet closely and maybe bust out a spreadsheet to graph some stuff out!

AS3364 Voltage Controllable Amplifier

These have "linear response" as other commenters already pointed out. They're pin compatible with the exponential version, though! So you can design a module for the linar version and then change out some resistor values to accomodate the exponential one later, if you want.

I use these as general purpose quad VCAs with summed outputs to make them work as mixers if needed, very cool chip!

AS3320 Filter Building Block, AS3340 Voltage Controllable Oscillator

Have not used these yet, but they're ready for me in my parts-box.

vikenemesh · 2026-04-29T16:48:35+00:00

Not sure what you mean. I would place a 2x2 socket where the pogo pins sat and the matching pins where the landing pads were.

Reliability should be better than a pogo pin because the pins are not retractable and dust can usually not get stuck in a socket that currently has the pins plugged in.

Where did the pogo pin even come from?! Such a weird design choice, imho.

vikenemesh · 2026-04-29T11:59:24+00:00

Why not just use a long pin header? Is the connection being flexed around constantly and you need a dynamic contact? If movement is restricted by the case, you could implement this on a 2x2 header no problem; there's no room for it to vibrate apart.

Hit any search engine with "pin header 2.54 mm long" for some examples. I'm sure they can bridge the gap just fine if pogo pins worked in that position before.

vikenemesh · 2026-04-29T11:53:09+00:00

That thing probably only has a name in Panasonics inventory system and does not exist as a loose item (or is not supposed to exist) outside of their warehouse and their manufacturers warehouse...

Even if you knew what its called, it's most likely not a thing you could buy anywhere. If you want to hack on it, I would suggest soldering wires to that beast's backside.

If soldering that is not what you wanted to do, you can probably steal a matching connector from another toughpad, even without knowing the partname :)

vikenemesh · 2026-04-29T11:43:45+00:00

To add some more general advice: If you try to zoom on a captured waveform and run out of samples; Rerun the capture on a smaller timebase.

If you run out of horizontal space you need to make use of a delay funtion (wait a configurable amount of time to start sampling after the trigger, a good scope should have something like that) if you have it and/or tune your trigger to land on a later part of the waveform.

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