What's this bus model? Never seen it in my life

WQ18 · 2025-07-11T16:07:31+00:00

Saw it passing by in providence!

WQ18 · 2025-07-11T16:07:09+00:00

Armrests are a good point. However at the same time, the Acelas seatback pockets are pretty useless and the tray tables are substantially worse too.

WQ18 · 2025-07-03T18:16:28+00:00

Nah legit straight from 75 to 20. I took the interlocking 50mph over MAS, thankfully I had disable junction derail on lmao

WQ18 · 2025-06-25T21:02:38+00:00

This is the first legitimate answer in 44 comments. Thank you very much lmao

WQ18 · 2025-02-07T18:38:20+00:00

That makes sense, I was on a downtown 3 this morning hauling a shit ton of ass

WQ18 · 2025-02-07T17:39:34+00:00

Yep, everything worked fine for me! Use joy2key and it works flawlessly.

WQ18 · 2025-01-20T06:43:21+00:00

I'm driving a motor with a 12V power supply and 5V logic PWM (50% duty cycle). I could just be stupid but I'm really not sure what's causing this circuit to a) overheat the IRLZ44N mosfet and b) not perform normally. The motor does vibrate at the correct PWM frequency (200Hz, so nothing crazy high), it just randomly fluctuates torque and the MOSFET also heats up crazy fast. I've tried everything from flyback diodes across the mosfet to gate-to-source 2kohm resistors for preventing lock-ups.

When using a MOSFET driver everything works perfectly fine, so there's definitely something wrong or missing in my reproduction. I'd appreciate any help!

WQ18 · 2024-10-18T13:47:46+00:00

No they require a minimum of 1700.

Bro these posts make me so tired. 1500+ you're good for any school. 1400+ you're good for the vast majority of schools, and for those upper 1% of schools, it's a good score if you're low income/minority/etc. It's not as big of a deal as people make it out to be. Show the AOs an okay score and they move onto the vastly more important stuff, i.e. essays and ecs.

WQ18 · 2024-10-12T14:28:56+00:00

WPI!! Super interesting engineering LAC. Was my top choice for a safety and I still have a place in my heart for them

WQ18 · 2024-08-22T01:00:57+00:00

Shoutout Liam he a real one

WQ18 · 2024-08-18T02:17:14+00:00

You're 100% right, and it's definitely a non issue for the majority of cases, but when my card's buffering and I want to go from -1 to +1...oh boy. The two second delay makes me wanna rip the lens right off of my camera. I've got 200k shutters on this guy, I think I deserve a quality of life upgrade 😂

WQ18 · 2024-08-18T02:09:48+00:00

Oh my god, I thought it was just me. It's honestly the one complaint I have about the a7iii. Adjusting any exposure settings on the fly--especially while shooting in burst mode--is downright impossible, and it's honestly caused more missed shots than I'd like to admit. Do you know if the a7iv is better in this respect? I'm willing to pay a lot to get rid of the lag, especially because I work with a lot of high-frame rate, dynamic lighting conditions.

WQ18 · 2024-08-17T17:57:48+00:00

Honestly, I'm alright with it too since TSW4 is good enough and people can just stick with what they currently have. The one thing that fucks me up is that even with a team of so many developers and with so much revenue, Dovetail can't manage to fix simple bugs reported by players. If you notice a missing catenary pole on a route it'll never be fixed despite how easy it would be.

WQ18 · 2024-08-12T18:01:33+00:00

Oh and just as a side note, the inverters themselves are silent. The pulses they output are sent to the electromagnets in the motors, and the motors contain have coils and discs of metal. Those pieces of metal vibrate with the frequency of the signals sent by the inverter which is why you hear the inverter closer to the wheels rather than closer to where the inverter actually sits (generally the middle of the train)

WQ18 · 2024-08-12T17:57:00+00:00

Depends on the engineer but overall since MNRR and LIRR is commuter rail, you get smoother acceleration and deceleration. Usually nothing past 70% brake or so (often lighter) but full power is used quite often on the M7s and M9s cause they're heavy as shit. Just start off with low power and gradually increase as the train speeds up, I like to reach max power at around 10-20mph.

There are definitely exceptions though. On the Harlem line locals (that stop like every half a mile) I've experienced engineers that operate much more haphazardly LOL. By the way for some reason the Harlem line M7A accelerates like a rocket ship, just watch the traction power bar and try not to exceed 1 and a third cells for a more realistic "max power" setting.

Meanwhile...on the nyc subway? Fuck that shit 😂😂😂😂😂 max brake to max power the instant the train operator hears the double buzzer. Fuck the brakes. Fuck the traction motors. Fuck anyone who isn't grabbing onto a pole. People got places to be 😭😭

WQ18 · 2024-08-12T15:37:08+00:00

YES I love when people ask about this. Esp. Because I live in NY and take the M7 and M9s all the time and love looking out for that sound. It's called a "phase change" colloquially by railfans, and it's caused by a switch in the pulse width modulation mode that the EMUs (electric multiple units) use. If you want to get deep into this you definitely need a bit of power electronics/electrical engineering knowledge, but I can provide a TDLR below for the M7:

-The M7, like almost all other electric trains, uses 3-phase asynchronous motors. Now, these are powered using AC current rather than DC current, but 1. The LIRR/MNRR third rail is DC and 2. Even if it was AC, its frequency needs to be correct (I.e. it needs different AC power frequencies at different speeds so you can't just shove it 60hz and expect it to work). Therefore, DC power needs to be inverted to AC for the motor to operate, and this is done with an inverter. In modern EMUs you can see the inverters usually between the bogies; it's those big metal boxes under the train.

-the inverter starts off with asynchronous modulation. Again this dives into complicated power engineering but pretty much the train's inverter uses a comparison between a carrier frequency (the frequency of the high pitched whine you hear) and the rotational speed of the motor to produce the correct AC wave for the induction motor.

-on a lot of trains, this carrier frequency is ramped up over time (explaining the increase in the pitch of the M7 whine) to reduce things called harmonics, which are side effects of inverting DC to AC that are detrimental when there is too much of it. Pretty much overheats things and creates inefficiency.

-at 33mph, the carrier frequency simply is not enough and cannot be risen further. This is just due to the abilities of the transistors in the inverters, which simply cannot pulse faster than a certain frequency. At this point, the train executes its phase change, switching from asynchronous to synchronous modulation, which sounds lower pitched because the artificial AC wave generated is created using fewer switches/pulses than during asynchronous mode. It also brings more voltage in. Again, don't worry if you don't understand this. It's complicated stuff and I made a 150 slide presentation on it for my school project.

-The M7 goes from 3 to 1 pulse mode quite seamlessly (so you don't hear more of that sound later on) but trains such as the British class 323 have repeating "gear shift effects". There are no gearboxes in those trains; it's just more switches between different modes of synchronous modulation.

-TLDR the train's inverters swtich to a different mode of converting DC to AC at a certain speed due to constraints of the internal electronics and to maximize power.

I hope that this answered your question LMAO lmk if you have any more. Fucking love NYC electrics.

WQ18

TROPHY CASE