I was expecting Hal

On the other hand, an experienced driver might forget it’s there since they never use it. Add in a high-stress situation, and you get a problem.

Now imagine you’ve been driving the Tesla for a long time and don’t ever use the manual release because you’re not supposed to so you don’t mess up the window. And then imagine you’re in a high-stress situation. That’s how having an unmarked backup can fail.

Plus, that handle doesn’t even look like a normal handle - I have never see a car where you pull up to exit instead of sideways away from the door.

On the other hand, if you never use the mechanical release and have spent a long time only driving your Tesla, wouldn’t it be possible to forget it’s there while in a high-stress situation?

Sure. And you can import them too if you’d prefer.

Do I just connect thermal pads to the ground plane and call it a day?

Yup.

Wouldn’t that make the components hard to solder with hot air?

Sorry, I’ve never tried hot air assembly.

Do I make an isolated polygon that only acts as a thermal pad?

Ideally the copper area is big to spread out the heat. If you have an isolated polygon it can’t spread very far and buys you less cooling.

The 7333A is a linear regulator, which means it drops voltage by converting power to heat. Typically those make sense when the input voltage is close to the output voltage or the load is very small. If it’s getting too hot, the load is high enough that the efficiency will be very bad…whether or not this is a problem depends on your application.

Some random site claims 170mA and another claims up to 400mA. 170mA * 8.7V (12V in minus 3.3V out) = about 1.5 watts, which is too much for a TO-92 package.

Can you use a tiny buck converter instead? Or a larger package for the linear regulator that can add a small heat sink?

As for your actual circuit, the second transistor is an interesting idea (you’re using it to invert the state so you can have the GPIO pulled in the non-problematic direction?) and I don’t have enough experience to give further suggestions.

I’m not entirely clear on the problem, but yes - the circuit as drawn makes the microcontroller pin start high, then fall after some time. Do you need the microcontroller pin to have a different voltage than the transistor base (I assume when you said gate you mean base…gates are for FETs), or is this good enough?

Would a circuit like this power-on reset circuit work for your application?

LFP cells have excellent cycle life anyway (2000+ cycles); is it worth worrying about staying at 95%?

What is this list sorted by?

Are you using leaded or lead-free solder? If it’s lead-free, it has to be hotter and you may also find extra flux helps.

Realistically, I usually stop if I see a car even if I have right of way, because I’m the one who gets hurt if they roll through. Modern cars’ A-pillars are thick and I know I’m hard to see. I only exercise my right when there aren’t cars near the intersection, or I made eye contact with the driver and they waved me through.

But why would a driver have to know I’d treat it as yield? If they arrive first, I have to stop—same as if it were a stop sign—and if I arrive first, they have to stop: same as if it were a stop sign.

The only difference a driver will see happens if I arrive first and don’t stop, and then they’ll either know the law and appreciate me getting out of the way faster, or not know the law and think I’m one of those aloof cyclists. But they still had to stop.

Some jurisdictions actively take the opposite approach - bikes can treat stop signs as yield signs!

Hopefully a healthy used market develops over the next few years as children grow out of their child-haulers. They seem awesome, but for people not lucky enough to live in a place where they truly enable owning fewer cars, the cost is still squarely in “luxury goods” territory. As it stands today, it’s hard to justify a $4000 bakfiets against a $250 trailer, especially when a removable trailer lets you keep using your bike as a regular bike too.

This was more interesting than I expected. Though they didn’t clarify why it costs $700,000, given the context I assume it’s customers on slower devices/connectivity leaving rather than something like bandwidth?

It’s similar to AC-DC. From a simplistic perspective, efficiency at idle will be 0% because the converter itself still uses some power, then efficiency increases with load since the converter overhead becomes less significant as the useful work increases. Googling “dc dc converter efficiency curve” gives plenty of results.

What are you switching? There’sa good chance (but no guarantee) even an ultra-cheap switch is fine.

Burley kids trailers have a weight limit of 75lb (~34kg) for the single and 100lb (~45kg) for the double. Are used double trailers available there?