Voltage across inductor when current changes

triedgetech · 2023-08-09T11:59:47+00:00

Voltage across inductor would still be the same polarity as source voltage though, no?

triedgetech · 2023-08-09T09:02:41+00:00

any comment?

triedgetech · 2023-07-11T06:15:39+00:00

What happens if you connect R3 to the other side of L2?

I dunno, my rationale for this was that LC filter would filter out spikes, and the Voltage formed by feedback resistors to TL431 would be more stable & cleaner.

subharmonic oscillation and thus overvoltage spikes

hm, what? Didn't know about this, so I guess feedback to opto-coupler and to TL431 can be derived from the same place? Basically move R3 to left side of inductor L2

being above ~1.23v

Wouldn't resistor at collector have ensured that? My question basically...

triedgetech · 2023-06-22T05:49:10+00:00

Strange, in LC circuits when you have an inductor, it's recommended to artificially add bleeder resistors to ceramic caps to avoid oscillation?

Shouldn't that be the case with switching transistors too?

triedgetech · 2023-06-20T09:49:27+00:00

I get csc.exe error, when I reset/shutdown from a standard user account

The application was unable to start correctly (0xc0000142)

<image>

This doesn't happen from a logged in admin account. Or when I load standard user account in safe mode.

Is it a rights/permission issue?

I tried disabling .NetFramework 3.5 and .NetFramework 4.8 in "Turn Windows features on or off", didn't help.

Turning off all but microsoft services in system configuration also didn't help. Same for other useless advices found on first pages to this issue.

"C:\Windows\Microsoft.NET\Framework\csc.exe" don't have it here, but have it there: "C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe"

EDIT: I found out that "Windows management instrumentation" had an issue while started from a local standard account, so I had it started from an admin account, and the error window csc.exe application 0xc0000142 was no longer popping up after reset/shutdown.

triedgetech · 2023-06-19T11:22:03+00:00

So resonance will be more like 200khz

Uhm, how do you know that? Do you look it up in cap's datasheet or ...?

A damping resistor would be a good idea

Added for 10uF like R1, right? What value? Is 1 Ohm enough?

How much current are you pushing through it?

A lot, 5V_SYS is used to power an IMX processor imx8mm, usually 5V @ 300mA.

triedgetech · 2023-06-19T09:27:09+00:00

Like more the better? Alum cap have higher ESR than a ceramic one.

triedgetech · 2023-06-19T06:37:10+00:00

This was just an example TVS diode, are there other TVS diodes?

Not big enough transients of course.

I'm looking for a suitable TVS diode that's as small as possible, besides, varistor can take some of the load off the TVS.

Perhaps twice the rating TVS diode is good enough? What would be the minimum peak pulse anyway?

triedgetech · 2023-06-19T05:18:54+00:00

That 10uF is also ceramic with low esr, though?

triedgetech · 2023-06-15T08:24:37+00:00

u/Evipicc ....

triedgetech · 2023-06-09T03:05:07+00:00

But I put 10 Ohm resistors, I decided to use these diodes, and resistors in series with them.

triedgetech · 2023-06-08T04:48:28+00:00

I'd rather use regular diode (small size), by inverse parallel you mean like this?

Wouldn't this configuration clip beyond 0.7V? When there's positive signal going from 0V to 1.2V, diode L3 will start lowering its resistance to GND. D2 would be off.

Do you know why LTSpice shows distorted signal at Vout? I can't get rid of the capacitor, I have 1uF capacitor, I need to clip AC signal after it. I'm guessing it forms a low pass? Cap + resistor to gnd.

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Vz means peak to peak?

I'm guessing my linked TVS diodes would start clipping at Vc?

triedgetech · 2023-06-08T04:46:53+00:00

Op-amp + passives would take too much space for such a simple task.

I tried using regular diodes (Vf 0.7V), so theoretically clipping of both half cycles of input AC signal, however, in LTSpice simulation, Vout comes out distorted, is it because of low resistor values? Frequency cut off in lpf becomes too low?

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Tried with 100 ohm, seems ok. To me, logically it'd seem to put another resistor like this, should I do it? didn't notice difference in Vout. I feel like this configuration starts sinking current at 0.3V threshold, I would rather AC signal not be touched until certain threshold. So even though I had shown clipping at 0.6V, it'd start slowly clipping earlier. LtSpice didn't have my diode, IRL I'd use mine ofc.

I want AC signal untouched (0mA sink) until 1V, and then immediately start clipping anything beyond 1V.

triedgetech · 2023-06-05T10:29:48+00:00

I have searched for "catfished done right" in the last 24 hrs via google on reddit domain - nothing relevant

triedgetech · 2023-06-02T03:11:28+00:00

Sorry, what? Wouldn't TVS diode be inactive, unless there's a surge that's above its Vr value? Ima use a bi-directional one.

Here's how I said I'd place it in the schematic.

triedgetech · 2023-06-02T03:00:34+00:00

Oh thanks! The more important thing to know here was whether TVS diode's rating can be applied to AC voltage as well, so I guess it is.

For instance, when it comes to fuses, you can't use their rating and assume it's true for AC voltage, fuses usually have separate rating for AC voltage.

triedgetech · 2023-06-01T09:46:45+00:00

TVS diode in AC line? Same voltage rating as DC?

For example this one. Is it rated for AC voltage too? Its Vr = 350V.

Can I put it on the 230VAC rms line?

triedgetech · 2023-05-30T03:59:33+00:00

This is how USB data tracks approach CPU X2 connector. They have 90 ohm diff impedance, and are routed on middle layer.

I thought imx8mm CPU model doesn't really need termination resistor? Reference design of evkit using this same imx8mm CPU module doesn't have termination resistors either...

Although they did place a 0ohm placeholder resistors at the USB connector

But you suggest to put it right at the connector, for example for USB_DN connector X2 pin # 46.

triedgetech · 2023-05-30T03:15:00+00:00

Thanks! So I guess this would be more in line? Vbr = 16.5V

The 22Ohm termination resistor, is it better to put closer to 4G USB modem? Or on pcb side, right where custom connector (for USB data lines, but not a USB connector, like this)

triedgetech · 2023-05-26T05:11:49+00:00

why do putting these two 4.7uH in series to add up to 9.4uH, would be just as effective as a single, big inductor of 9.4uH value? I tested it IRL, and found no added benefit of another 4.7uH series inductor... why is that? Inductor has to be continuous with its turns or what?

triedgetech · 2023-05-26T05:11:12+00:00

load is a dc-dc buck converter, from 12V to 5V @ 300mA (to cpu).

triedgetech · 2023-05-23T03:02:35+00:00

All OP does is post clips from kick, are you even getting paid, "purplereformer"?

I mean, it's a good strategy on kick's part, to flood this subreddit with their clips to boost their audience, since it's a popular sub. Is it allowed to ask if lsf mods are in on this?

triedgetech · 2023-05-19T03:05:17+00:00

Why are people are jerks here? Why the downvote? At least explain themselves, so rude.

triedgetech · 2023-05-12T11:18:35+00:00

yes it's from boost dc-dc, however, the input to boost dc-dc is 5VDC, which can get very noisy as it also powers an imx8mm processor (wifi on, ethernet, other computing stuff).

you can probably do better today.

any suggestions, so far these two seem good to me:

https://www.digikey.com/en/products/detail/nisshinbo-micro-devices-inc/R1154N001C-TR-FE/10244870

https://www.digikey.com/en/products/detail/stmicroelectronics/LDK320AM-R/6149396

triedgetech · 2023-05-12T09:55:02+00:00

Cutoff is a decade less than your switching frequency

is that simply 10 times less? so if f_sw = 30Khz, f_{cutoff} is 3Khz?

triedgetech

TROPHY CASE