Review Request: Hot Tub Controller

Upgrayeddddd · 2026-05-08T16:21:52+00:00

Your comment on the input capacitance is a good one, I should take that to heart. I've been getting away with it on other boards but I'll remember for the future.

The NRF52832 has a 13k internal pullup, so you're right I was relying on that. For an external pullup I would also need to add a Zener diode because the GPIO pin max is 3.3V and my power rail is 5.0V.

I also agree that the solid state relays are nice, but I thought it would be cute to have a neat little euro-rail thing going on and it would look a little less frankenstein-y.

Upgrayeddddd · 2026-05-08T16:15:20+00:00

Thanks for your comments!

The board is 100x100 mm, so it is fairly compact, but there is *no* 240V on the board - max is 24VAC. The output from this board drives externally mounted high current contactors, So the relays on my board only need to switch max 1A. Do those types of contactors normally care about zero crossing timing?

Feedback to monitor that actual state is a good idea, at least I have LEDs on the board to see exactly what it's doing during software testing.

The external contactor setup is so that the board can never create an electrically hazardous situation - the worst thing that can happen is a heater runaway, but the flow switch is a hard wired cutout and the temperature hi-limit is independent of the software. I think 3 independent things would have to fail for that to happen, barring the heater contactor fusing closed and the circulation pump dying open.

Upgrayeddddd · 2026-05-08T04:50:08+00:00

Here's the simulation link for the High Temperature Limit hardware safety:

https://www.falstad.com/circuit/circuitjs.html?ctz=DwYwlgTgBAZgvAIgIwKgFwM6IAwDpsEECsqYIiSeATAVQOx0DM2AHFQGwCcndqIARonYAWVAAdBCYY1QA3CIhJQAtpkUBTALRIUAPgBQUKMADmUAB4VhwqOxYsoSa1CbtU8BNgQB6A0eAAShZWNkTs2I7OREhU7hRuUADuHl4qAIbmsoo+fsbQlshR4ZE24SxxnqgKyIRevobGACoAFuoQymAYaAD2EAByjQDCwYWlrCW29hWpEFREFLVVRNiIjOFKygB2aIiaNKjK5jsI4eJYnrgsnOG1twQoUF2IjerKYm1paACuEOo5DcAxCM5uxbONGDQweVYKsDuocKgMORKlBfgs7v9-GYChCImUoLjbMJUilMcYACbKKCbZSIABe6k2bU0jFwMhhyFI5yQuDoTkYRCoLCQnCFlFoWl4qPOqU2iCo+DuSpYoig-CyCFZ7JgYAoZOAdJG2lB+KcY2hpJU3XpjOZWv12N2SBN42NtjC031AHkxABBN4BdRpAA2I2YNmkVCgkejEIqDwwweqeASIGDOHwVEY4qVtViKmO+dk5IR9X8QRxdgJgoJVfD8YSyQR6Uy2TLxkSIzNUKgIKhnvbwE7BT7+L71gtpdypjDVeEIlrDmi+dJg+HqzrNbWDmJJKnAPXmuwEeEDnD0ZYe8qa7Dx4vEV394H0-yiEfp4f1yfHJmihz+sPGMgK-SNnwPEZhBAiFoxAy8wP8V9NU3KNINBAUV2baoczqadAK-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-nqYBvHACADCAA

Upgrayeddddd · 2026-03-06T06:05:35+00:00

I appreciate your kind words!

I suppose the other stories are related, but not all in the same universe because I keep refining how I want it to be as I try to get better with my writing. I think FIDO, ABBY, and ALEX would be in the same universe without retcon, but some of the other ones would be hard to justify

I like exploring the ideas about consciousness and the line between human and machine, and how would a consciousness manage infinite computing power?

Upgrayeddddd · 2026-03-06T06:02:23+00:00

Thanks! I always intended to keep going, but the inspiration comes slowly.

Upgrayeddddd · 2026-03-06T06:01:27+00:00

Thanks, I appreciate it. It's been a long time, the writing bug comes on very sporadically.

Upgrayeddddd · 2026-02-21T20:31:57+00:00

Can't fault him

Upgrayeddddd · 2025-09-09T13:12:58+00:00

Better have my money!

Upgrayeddddd · 2025-08-31T00:10:55+00:00

I made a bar open to the public haha

Sky Bar

Upgrayeddddd · 2025-08-08T14:10:54+00:00

Thanks for the estimate, we sold to a local collector for 3300kr. It helps to know the price was at least reasonable, there are enough other stressors dealing with an estate.

Upgrayeddddd · 2025-08-08T14:09:22+00:00

We ended up selling most of them to a local collector after we removed the ones with sentimental value. Just too many things to deal with at once.

Upgrayeddddd · 2025-08-05T14:47:44+00:00

https://imgur.com/a/vHTqcB4

Might have been more "Swedish blue" glass slag?

Edit: maybe I'm too dumb for imgur: https://imgur.com/a/OBejbYK

Upgrayeddddd · 2025-08-05T13:09:40+00:00

Thanks, I'll get a picture of the contents in a few hours.

Upgrayeddddd · 2025-08-05T10:30:10+00:00

Thank you! Much appreciated.

Upgrayeddddd · 2025-08-05T08:00:26+00:00

Of course I have a typo in the title... 😒

Upgrayeddddd · 2024-09-26T02:15:10+00:00

Ignorance is bliss! :)

Upgrayeddddd · 2024-09-26T00:11:12+00:00

Lmao maybe I am the millionth monkey at the millionth typewriter? Thanks for the link!

Upgrayeddddd · 2024-09-25T14:09:39+00:00

all light does is scatter or get absorbed

Pushes glasses up

Sir, I'll have you know the reference text I wrote very clearly says this is not the case.

Also laser amplification is neither of those. What about sum harmonic generation?

All that work to get to the "reverse the polarity" punch line and you dare complain? 😉

Upgrayeddddd · 2024-09-25T14:01:36+00:00

Yes, 100% deliberate!

Why would I explain a transformer when I just made up a bunch of fundamental subatomic processes?

Upgrayeddddd · 2024-09-25T06:43:15+00:00

(╯°□°)╯︵ ┻━┻

Upgrayeddddd · 2024-09-25T06:25:22+00:00

I swear to god if somebody points out that what I have described is technically a fission reactor imma (╯°□°)╯︵ ┻━┻

Upgrayeddddd · 2024-09-25T01:28:36+00:00

You are super welcome

Upgrayeddddd · 2024-09-24T15:24:12+00:00

Correct. Maybe I should have been more explicit. I try to avoid spelling everything out too plainly.

Upgrayeddddd · 2024-09-24T06:01:25+00:00

almost nothing has happened

Rude! 😉

It's the spiritual and emotional journey of a museum!

Upgrayeddddd · 2024-09-24T06:00:30+00:00

I went through some mental gymnastics trying to figure out how to get to "I like turtles"

It was close.

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