Hardware Is Hard? • Hacker News Board

Re: Hardware Is Hard?

#11

Post by prdpx7 » Mon, Apr 20, 2026, 6:47 AM UTC

Neywiny wrote: post #3

Thoughts as a computer engineer: 1. The motor demo didn't work for me (Firefox on Android). Nice to say it was made by Claude. 2. Voltage isn't like gravity. It's literally called potential. Voltage is the water being high up on the mountain. Gravity is the gravity, which was kinda the point of the analogy, no? 3. A Tesla has thousands not hundreds of 18650s. But I guess that's a superset. 4. For motor speed, I would…

>1. The motor demo didn't work for me (Firefox on Android). Nice to say it was made by Claude.

oh! i did tested on firefox with different devices on my laptop. but not in actual android phone. thanks for flagging it

>2. Voltage isn't like gravity. It's literally called potential. Voltage is the water being high up on the mountain. Gravity is the gravity, which was kinda the point of the analogy, no?

yeah! my bad. i might have wrote few things when i was just reading up and writing as i am trying to internalize what all these things mean

>5. PWM wasn't explained right here. You can most certainly vary the voltage without PWM, and it's not just any old modulation you want. You want a binary output so your transistors don't go linear, and you can control the average power. PWM is easy for linear scaling. But you could presumably use other modulations.

there are probably 10 more ways to make voltage dance - and i only read about two. one is resistors and other is PWM.

>Would be good to understand what the power chain is to make sure nothing blows up.

The blog has link which points to exact wiring instructions including adding buck converter. again! the purpose of this blog is not to explain every bit in detail. it's about what i have learned - because before doing all of this - i had zero clue about everything

Re: Hardware Is Hard?

#12

Post by prdpx7 » Mon, Apr 20, 2026, 6:49 AM UTC

general1465 wrote: post #8

Depends what you are doing. Digital circuits are not really that hard. You are just repeating known patterns and keeping the voltage in correct level (3V3, 5V, ...) unless you are doing some bleeding edge stuff in GHz range. And because these circuits are very deterministic it is also simple to emulate them down to the transistor Analogue circuits on the other hand are massive PITA. They have their own mind, reacting…

haha! i am just starting up. will see how the journey goes. thanks for the heads-up about analouge circuits

Re: Hardware Is Hard?

#13

Post by Neywiny » Mon, Apr 20, 2026, 1:07 PM UTC

prdpx7 wrote: post #11

Neywiny wrote: post #3

Thoughts as a computer engineer: 1. The motor demo didn't work for me (Firefox on Android). Nice to say it was made by Claude. 2. Voltage isn't like gravity. It's literally called potential. Voltage is the water being high up on the mountain. Gravity is the gravity, which was kinda the point of the analogy, no? 3. A Tesla has thousands not hundreds of 18650s. But I guess that's a superset. 4. For motor speed, I would…

>1. The motor demo didn't work for me (Firefox on Android). Nice to say it was made by Claude. oh! i did tested on firefox with different devices on my laptop. but not in actual android phone. thanks for flagging it >2. Voltage isn't like gravity. It's literally called potential. Voltage is the water being high up on the mountain. Gravity is the gravity, which was kinda the point of the analogy, no? yeah! my bad. i m…

I don't think you understand the point of PWM then which is ok. A resistor wouldn't provide runtime control of the power going to the motor, unless you had a programmable resistor which would likely explode from the current induced heating. And that's fine, because everybody just uses PWM, but if you do a follow-up I recommend investigating why the motor is connected and controlled in the way you did it.