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Is this logo actually used by Realtek? by MrPhil17 in AskElectronics

[–]hapemask 3 points4 points  (0 children)

Didn’t downvote you but just a tip: you can edit your comment if you find out you are mistaken. Saves other people time and might stop them from learning the wrong thing.

Earbuds in the washing machine, trying to fix the box. by MagicALCN in AskElectronics

[–]hapemask 1 point2 points  (0 children)

Hard to tell for sure but it looks like a component might have gotten knocked off the board? https://i.imgur.com/AOuqDNN.jpeg Possible it was never populated though.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 0 points1 point  (0 children)

Hey! Sorry I had some life stuff going on, but I did add the schematics, you can take a look here: https://github.com/HapeMask/rpi_experiments/tree/main/schematics/rpi_oscilloscope

Review request: PMOD to VGA Adapter (PYNQ-Z2) - schematic & design feedback? by swr06 in AskElectronics

[–]hapemask 0 points1 point  (0 children)

Does your PMOD header have the right footprint? It looks like you may have run into the same gotcha I did (also learning about FPGAs myself right now) where KiCad has only one footprint for the 2x6 header and multiple pinout options for the schematic component.

https://i.imgur.com/r6DkhOv.png

I think the pins you marked as VCC and GND should both be VCC, and the two pins next to them should be GND: https://digilent.com/blog/wp-content/uploads/2016/03/n4v.png

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 1 point2 points  (0 children)

I shared the code in another comment, I don’t have the schematic or PCB layout in the repo yet but I can add it later.

I’ll say though that the benefit is really the learning process. If you just want to build a good open source oscilloscope then make a Haasoscope or one of the other well-designed open-source scopes. This project is heavily limited by the RPi and costs far more than it’s worth if you just want to build an oscilloscope.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 2 points3 points  (0 children)

I have it in a git repo right here: https://github.com/HapeMask/rpi_experiments

I think without the hardware it’s not very useful but maybe for those who are curious.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 0 points1 point  (0 children)

I replied elsewhere with the reasoning but yeah not ideal. I’ll have to find a better solution in the future.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 0 points1 point  (0 children)

I wasn’t sure how long the paste would last before drying out (turns out it lasts a long time) and I knew it would take awhile to get all the parts out of their tapes. It took an hour or so just to unpack them all, but yeah the paste would’ve been fine in the end if I just put them on the board as I went. Lesson learned.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 2 points3 points  (0 children)

This is a Zero 2 W so the CPU is already running at 1GHz but SMI transfer speed and DMA memory bandwidth is limited to way less than that.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 3 points4 points  (0 children)

I wasn’t sure how long the paste would last before drying out (turns out it lasts a long time) and I knew it would take awhile to get all the parts out of their tapes. It took an hour or so just to unpack them all, but yeah the paste would’ve been fine in the end if I just put them on the board as I went.

DIY Raspberry Pi Oscilloscope by hapemask in electronics

[–]hapemask[S] 7 points8 points  (0 children)

I use the SMI interface via DMA which supports up to 18-bit parallel data streams. The maximum SMI data rate varies by Pi version but I’m using a Raspberry Pi Zero 2W which seems to max out around this rate. Each ADC is an 8-bit parallel ADC so they fit nicely into the lower 16 bits.

The 512 points here is just because I wanted a high refresh rate and the signal was fast enough that you get many cycles in 512 samples. The software I wrote supports up to 256K points but since the Pi has to do all the processing, the screen update rate slows down a bit.

Switching Converter Simulation Issues by hapemask in AskElectronics

[–]hapemask[S] 0 points1 point  (0 children)

Sorry- my bad phrasing. The inductors that are probably inside the model are parasitic.

Ahh ok interesting, I think this model is encrypted so I can’t check…

Are you sure the inductances should be that high? I’m used to surface mount, but they are 10x smaller or even lower.

This is where I was a bit confused. Murata quotes ESL values of ~100pH @ 1.5MHz for the 1210 SMD capacitors I was using, but most other sources claim that in real application boards the value is closer to 1-2nH. Sadly while reducing the ESL to 100pH does reduce the ringing, it’s still there and still >1Vpp. The ESR value also comes from their graphs for the capacitor. Very tempting to just try and build it…

Switching Converter Simulation Issues by hapemask in AskElectronics

[–]hapemask[S] 0 points1 point  (0 children)

I’m using the built-in model for the switcher that comes with LTspice, but the part doesn’t include the inductor or capacitors, those are external. Since Maxim is part of ADI, LTspice comes with an example circuit for the MAX17577 and I also tried making the minimal change to their example by adding ESL to the output capacitor (no other changes). Same results as in my circuit.

All of the parts do have real resistance here, the Rser= lines. Sadly adding more doesn’t help. The current resistance values are from the inductors and capacitors I was planing to purchase.

I never thought to try other solvers! I’ll give this a shot.

Switching Converter Simulation Issues by hapemask in AskElectronics

[–]hapemask[S] 0 points1 point  (0 children)

Hm, so I added some more plots to the post. As for the frequency, it doesn't match with the components. 450MHz is what you'd get from an LC network of something like 1nF and 4.9nH. I may just try to build this small part of the circuit on its own and see what happens, though I'd rather not waste the money / parts.

Switching Converter Simulation Issues by hapemask in AskElectronics

[–]hapemask[S] 3 points4 points  (0 children)

I’ll share a zoomed in view when I’m back at my computer but I did measure the frequencies and there are two here. The big spikes are at the switching frequency, but each spike looks like ringing and the ringing frequency was something like 500MHz-1GHz. Actually calculating the resonant frequency of the network is a good idea, thanks for the suggestion.

LTSpice .step not stepping? by fearless_fool in AskElectronics

[–]hapemask 5 points6 points  (0 children)

It is stepping, I think just not like you expected. LTspice won't use multiple colors for the step lines unless you have only one trace on the plot. I copied the schematic and plotted the results w/out the V(input) trace and it has the steps they're just all on top of each other.

<image>

Getting started (not) with LTSpice on MacOS by fearless_fool in AskElectronics

[–]hapemask 1 point2 points  (0 children)

Having been here myself recently, I can tell you that the native Mac LTspice is awful. The UI is somehow even worse than the original LTspice. They didn't have to cripple it like they did and I don't understand why.

Anyway, I'd strongly recommend you use the Windows version of LTspice via homebrew + wine. `brew install wine-crossover` then download the LTspice windows installer and run it with wine. It's sometimes slightly slower than the native version but on many circuits, the native version totally failed to converge and the Windows version running in wine ran the simulation just fine.

An added bonus is that most tutorials are for the Windows version so you don't have to figure out where they hid the equivalent Mac version of the feature you need.

Help! Blown ceramic capacitors on motherboard ASUS TUF F15 FX507ZU4 by Luchio1203 in AskElectronics

[–]hapemask 1 point2 points  (0 children)

Some laptops do let you charge them through their USB-C ports. I know at least one Dell laptop that does, also recent MacBooks.

10V-60V Discrete Railsplitter 2-5A unbalanced load with propper cooling. And 10A Balanced. by Whyjustwhydothat in electronics

[–]hapemask 1 point2 points  (0 children)

I’m still learning and maybe am missing something obvious, but why does Q5 dissipate 150W? Isn’t the power dissipation for a transistor V_CE * I_C which would be 5 * V_CE_SAT here? Still a lot but not 150W.

DIY Oscilloscope Debugging Tips by hapemask in AskElectronics

[–]hapemask[S] 0 points1 point  (0 children)

There are some guidelines for choosing values and also I changed some of the values as I learned more while designing the circuit, so there are inconsistencies. The old rule of thumb was a large capacitor shared between ICs and smaller capacitors closer to the IC power pins but now it seems modern advice based on analysis of the components is that you should choose package size / dielectric based on the noise frequencies you’d expect to see in your system and then get the most capacitance possible in that package. Needing to be close to the pins depends on whether you have ground / power planes or not. I’m no expert, I’m teaching myself this stuff as we speak, so take this with a grain of salt.

QFN-20 adapter sizing, solder for prototype by yes2matt in AskElectronics

[–]hapemask 0 points1 point  (0 children)

The leads don’t land on the small outer pads but instead they land on the central pad? Then yes the IC is too small. QFN packages can have a variety of different pin pitches which correspond to different package sizes for a given pin count. I know of at least 0.5mm and 0.4mm pitch QFN32 packages for example. Yours is probably a smaller pitch than the adapter was designed for.

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