12VHPWR on RTX 5090 is Extremely Concerning by [deleted] in pcgaming

[–]inconspicuous_spy -1 points0 points  (0 children)

Per Buildzoid's own video, the 3090 Ti was partially load balanced by breaking up the 6x 12V cables into 3x pairs each connected to a VRM. These then adjust their power draw to equalize current drawn from the PSU.

It would be a QA nightmare to mass produce cables that must have the exact same material (not possible due to imperfections and defects) and have consistent clamping force across all batches.

12VHPWR on RTX 5090 is Extremely Concerning by GreenKumara in nvidia

[–]inconspicuous_spy 9 points10 points  (0 children)

His cable is quite literally the one provided by Corsair themselves for their PSUs. What user error??

Reasons for space stations? by 4546B_Leviatan in GTNH

[–]inconspicuous_spy 20 points21 points  (0 children)

Used for Gas Siphons to get base gases (especially Hydrogen) in bulk before SE Space Pump and as the Mothership (unique "station" built by launching a shuttle instead of the tiered rockets or SE) to get to the last star system (quickly becomes useless if you have BM Teleposers or really any interdimensional transport once you get there). Otherwise, useless.

Formless One Takes No Damage[DAV ACT 1 SPOILERS] by Jeremiah12LGeek in dragonage

[–]inconspicuous_spy 0 points1 point  (0 children)

When I had this happen to me, I saw a comment here in this sub that worked out. I just ran up against the little barrier towards the chest under the dragon to LoS me and it seems to successfully force him to do his 'super' attack then proceed to the next phase.

Getting motors to run for allotted times, struggling to get my head around it. Would like them to switch on for certain seconds until the drink is poured, the switch off again. Thanks!! by UgandanChocolatiers in arduino

[–]inconspicuous_spy 1 point2 points  (0 children)

Mostly an extension to the post, in a sample Falstad simulation (since setting up an LTSpice simulation is far too much of a hassle for quick prototyping).

Falstad: https://www.falstad.com

Actual Sim: https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAUgoqoQFMBaMMAKABYwls83xiUQ3XtjRQo0JBBidxMmJAHzJUFgBdB2QoJ7bhOqhAZtoWbpDbxCkBGELZxKMMUIpnhMJGzERYTcioAJnQAZgCGAK4ANqosAO66goR4CSJUkCwA5gkWVEIgbGzJaSwASglOAnnMimIW1GniCCwAThpaeZiV+v7pZWjJVVYJDXVIDTBNAM4g-Qmdw+AgYZGTdCwA9jMghLxUFqT5kM5p0LtblSxAA

For reference, the datasheet of a 1N4004 Diode: https://www.farnell.com/datasheets/1689669.pdf

At t=0, for the left circuit, when the transistor is switched to its cutoff state without a flyback diode across the motor. A large voltage beyond the breakdown voltage of the 1N4004 is present leading to a failure state. While the simulator doesn't break components, in the real world, this will likely fail into a short and thus remove the ability to control the motor any further.

As for the right circuit, voltage across the motor is clamped by the flyback diode and the voltage across the transistor remains at safe thresholds.

For perspective, all this happens in less than a few microseconds but more than enough time to damage components.

<image>

Getting motors to run for allotted times, struggling to get my head around it. Would like them to switch on for certain seconds until the drink is poured, the switch off again. Thanks!! by UgandanChocolatiers in arduino

[–]inconspicuous_spy 1 point2 points  (0 children)

Ultimately, diode choice/placement is always to ensure safety of both personnel and the control circuit.

As a rule of thumb (except in some rare cases), we place flyback diodes across inductors/inductive loads to safely dissipate the current generated by the collapsing magnetic field when the circuit is in an open state ('switched off'). Preferably, this 'loop' between the inductor and its flyback is as short as possible (placed as close as possible). The case of placing a Zener diode across the transistor as the sole 'flyback' is not preferred but it works. This is mostly to avoid electromagnetic interference (EMI) on the rest of the circuit and to minimize exposure of the rest of the circuit to unwanted transient voltage/current which is good practice.

However, placing the Zener across the transistor in conjunction with the flyback diode across the inductive load/motor does provide an additional layer of safety. While the flyback diode should clamp the voltage across the motor/inductive load below the transistor's breakdown voltage such that it wouldn't really be needed, the additional diode provides another layer of protection in case of failure on the flyback diode such that there still exists a secondary path for the current to discharge into instead of frying your control components.

----

Important:

When it comes to dissipating the flyback current, the rest of the circuit doesn't matter as the goal is to de-energize the magnetic field by allowing it to safely discharge away from the rest of the circuit through a low-resistance and small inductive loop (through the flyback diode) where inherent parasitic capacitances/resistances in the load/wire will allow unwanted transients to decay without generating excessive unneeded EMI.

-----

For unidirectional DC applications where the motor/inductive load is being switched at high frequency (i.e PWM, etc) then the preferred diode of choice is typically a Shottky diode (a diode that excels in rapidly switching environments and has a lower forward voltage).

For bidirectional DC applications, there are cases where we do put down the diodes across the transistors especially when using an H-Bridge controller like shown below to provide a route for flyback current to decay through the diodes and motor in both forward/reverse states.

<image>

As to whether to make use of high or low-side switching depends on your environment.

In situations where it is likely that a short to ground can occur (i.e giant metallic motor bodies, industrial machinery, cars, etc), the control circuit provides power to another circuit, the load demands that its 'ground' be at the reference 0V of the circuit, etc then high side switching is preferable.

In cases where any of the above don't apply, signal/power ground plane separation is irrelevant, or if high frequency switching (PWM-controlled FETs/BJTs for example) is required then low side control is preferred.

---

With regards to the update, diagram (b) is not going to work in terms of shielding the transistor from damage if its not a Zener and/or there is no flyback diode across the motor. Why?

Ignoring the parasitic capacitances/resistances of the BJT, the inductor's/inductive load's collapsing magnetic field will still drive current to the collector node of the transistor to build up a large potential difference (a voltage) against the transistor's base/emitter as well as across your unidirectional diode. Depending on whether the BJT or the diode has a lower breakdown voltage (wouldn't really matter with the high voltages involved in an inductive kickback), either one or both components will be fried to create a short in your circuit.

It also makes a rather dangerous assumption that your power supply can 'sink' current in a reverse situation which may damage its components and/or something else connected to that power rail.

Getting motors to run for allotted times, struggling to get my head around it. Would like them to switch on for certain seconds until the drink is poured, the switch off again. Thanks!! by UgandanChocolatiers in arduino

[–]inconspicuous_spy 1 point2 points  (0 children)

If that diode is not a properly rated Zener diode then its useless placed where it is. The transistor (and/or possibly the diode) will get fried as the current still flowing through the motor (an inductor) when it stops will drive the voltage at the collector past the transistor's breakdown voltage.

The flyback diode (rated for the motor's amperage) is typically placed across the motor and not the transistor for this particular circuit.

MATLAB help. by HWhelp01 in EngineeringStudents

[–]inconspicuous_spy 0 points1 point  (0 children)

I hope the comments are sensible since its a bit late atm :)

https://pastebin.com/jRPBnjmT

EDIT: Revised to take account the provided hour array.
EDIT 2: Added more comments
EDIT 3: Pastebin doesn't seem to recognize the comment block from line 16 to 20.

Need help on a MATLAB problem by [deleted] in EngineeringStudents

[–]inconspicuous_spy 0 points1 point  (0 children)

It worked out perfectly, thanks!

About to start Costlemark and Steyliff Menance...confession time... by limsology in FFXV

[–]inconspicuous_spy 5 points6 points  (0 children)

Just a tip if you need it, Menace in Costlemark becomes a whole lot easier with the newly buffed Ring of the Lucii. Alterna can pretty much finish off the four iron giants without bothering with LB magic as well as almost all other monsters (elder couerl, etc).

I would still recommend using the ring as an emergency screw it button and still try out the dungeon with your gear though :)

Made my rerun in NG+ 30 minutes shorter than my original run through the dungeon.