@Neo_Chen @sa2tms Exactly. I'd go as far as saying the "distortion artist" and "transparent reproduction" are the two major groups in the Hi-Fi audio world. Before DSP, attempting different amplifiers circuits were basically the only way to adjust the sound. And it's perfectly valid if one perfers tube distortion.

Unfortunately the paradox is that it doesn't have a clear boundary between the two groups, and we get all sorts of nonsense such as combining different transparent devices to "change" the (imagined or real) sound. And if it produces a effect, probably due to additional distortion, audiophiles will claim it have better "sound quality", whatever it means...

By audiophile standard, the best Hi-Fi in the world is a reference sine wave generator. Real audiophiles should listen to nothing but the 2 kHz oscillator Jim Williams built before his death in 2011 for testing a 18-bit ADC. It only plays a single tone, but they can enjoy the sound of that 0.00031% Total Harmonic Distortion! https://www.analog.com/media/en/technical-documentation/technical-articles/ubm_edn_20110811%2018bit%20adcs%20ad%20free.pdf #electronics

@a1ba if someone wants to report a bug, sending that 50 GB 7z file reproducer to the developer would be an "interesting" exercise. I still remember uploading my 16 GB disk image to AWS for reportitng a F2FS bug, I was impressed by hom much patience the developers had on me... :blobcatgiggle:

@puniko internyet

@chjara Just checked Voice of America. No it does not, disappointing.

Q: What do you say when you're searching for a high-voltage circuit, and finally found a suitable design that looks promising?

A: It has a big potential!

You know you're in a big company when...

There are more than two people in your corporate campus who play videogames nobody plays like Dwarf Fortress, Dodonpachi or Touhou Project.

USB Killer ordered, I'm going to unironically use it as a test device on my 1000 volts port isolator... #electronics

The last overvoltage protector candidate has arrived. Time to send 300 volts to each part and see which one blows up first... #electronics

* State-of-the-art microprocessor SoC built using the 7 nm node, one of the most complex process ever invented by humans.
------
* A capacitor charged to 300 volts.

Who would win?

USB Killer waveform captured - 4 kHz inverse sawtooth wave, 622 ns rise time, 172 volts AC peak-to-peak. The sawtooth wave itself is riding on a 138 volts DC bias, giving a total peak voltage of 310 volts AC + DC. The DC bias decreases as the stored energy goes down, the pulse stops after 20 seconds.

Unlike the original version, this particular variant uses a positive, not negative surge, and also adds a huge DC bias to the pulse. Its designer must have spent much time on improving its destructiveness. And curiously, it attacks only D-, not D+ data line, not sure if it's a manufacturing defect, or an intentional attempt to concentrate energy on a single line. #electronics

Curiously, each time the USB killer discharges, there's a loud "BANG" sound. A Gas Discharge Tube is used as the trigger it seems. It's kind of ironic, a GDT is normally used to protect a device from high voltage destruction, not to create it... #electronics

I put a 50 Ω load on the USB killer. At first it kept pulsing continuously for 30 seconds or so and stopped. Now it only generates one or two pulses into 50 Ω each time. Also, when the load is removed, the total pulsing time to a high-impedance load has also degraded from 20 seconds to 10 seconds...

Has this USB Killer just killed itself for good? :blobcatgiggle: #electronics

BTW, the USB Killer appears to have successfully destroyed my 20 dB RF attenuator during the test. :blobcatgiggle: #electronics

> testing the pulse-energy endurance of electronic components such as resistors and transient voltage suppressors.

I think I don't really need to design this HV pulser. Just realized the X Chapter in The Art of Electronics already has exactly what I was looking for. https://x.artofelectronics.net/wp-content/uploads/2019/11/3xp15_HV_pulsers.pdf #electronics

shorted to ground, now it's completely dead.

Success. The 100x transmission line probe (5.1 kΩ in series with 50 Ω oscilloscope input) is working really well, so far I haven't blow up my oscilloscope terminator yet. I'd say it's the go-to choice for high-voltage pulse measurements if you don't need higher input impedance. #electronics #usb

The original plan - let the USB Killer send its energy straight into a 50 Ω oscilloscope input through a big RF attenuator - is flawed. No reasonable RF attenuator can sustain such an energetic pulse.

New plan: Probe the voltage via a 450 Ω or 4950 Ω series resistor, this forms a 10x or 100x transmission line probe when combined with a 50 Ω input with good signal integrity. Also, the load should be installed on the PCB, using the instrumentation itself as a test load is a bad idea... #electronics #usb

More USB killer waveforms captured, unlike the last test (see thread) with an open circuit, this time it's connected to a 50 Ω load.

It keeps pulsing once it's connected, peak voltage is typically 140 V, but can be as high as 200 V. Pulse width is about 100 μs to 250 μs. Repetition rate is about 27 pulses per second. The pulse characteristics are poorly controlled, I suspect it's triggered by the arcing inside a gas discharge tube, typically used for surge protection (the irony...).

Like the last unit, this (identical) one also damages itself after continuously pulsing for a minute or so. It can no longer generate continuous pulses. #electronics #usb

Received two 100 volts electric shocks while testing this, Electroboom moment. Note to self: Do *not* touch the output capacitor bank without discharging... Even after the output went to zero, it only means the voltage is too low for the switch to turn on, but the capacitors themselves are still at 100 volts! #electronics #usb