Show HN: Sidebar – a private ESP32 intercom for five kids, no accounts | Hacker News Reader

Show HN: Sidebar – a private ESP32 intercom for five kids, no accounts

sundaradnus.ca

16 pointsnonstopnonsense13 comments

Hello all - Inspired by many who build/assemble for their daughters/sons, I took cue and assembled a two-way communication between my son and his friends. Nothing spectacular. Just basic stuff to talk.

He is eleven and doesn't have a phone. I wanted him to talk to his friends without an account, a feed, or an algorithm in between, so I built five ESP32-S3 touchscreen units, one per kid. Tap a friend's name, their unit rings. Tap Everyone, they all ring.

Each unit dials outbound to a relay I run, so no house opens a port. Audio is uncompressed 16 kHz PCM in 20 ms frames, AES-256-GCM with a fresh key per call, over UDP with an encrypted-WebSocket fallback. To be precise: encrypted to my relay, not end-to-end. No rooms, no recordings, no free-text contacts; the roster lives in a server-side allow-list.

I'm a PM, engineer by degree but not by profession - let alone a firmware engineer. I assembled this with Claude as the engineering partner, which is why the write-up includes what went wrong: I shipped an OTA that boot-looped my son's board, and separately "diagnosed" a Cloudflare outage that didn't exist because I tested from the wrong vantage point. Echo is still unsolved.

The enclosure was designed in FreeCAD by my son (11); the STLs are in the repo.

It was a fun and exhilarating work for me and my son - like most of you would have experienced.

Looking forward for your responses/feedback.

Open articleView on HN

As a grandparent without your skills, I am impressed with the idea and how you included your son in the development. Especially useful for parents who (like you) wish to delay smartphone purchase for their kids. Is any of this patentable? Sell to a toy company for mass production?

Thank you!

None of these are patent-able or sell-able. Many such ideas already exists and are sold. This is a one-off solution where I have built for my son and his friends. I could have bought a subscription and devices from elsewhere - but thought otherwise.

I could, potentially, build up infrastructure and expand - but, that's too much of a financial constraint and too much time away from my personal life.

The code and designs are out there for anyone to stand this up for themselves. Or I can help assist to set it up.

You should play more with your kids before they grow old.

Fair point and unsolicited parental advice. There is only so much a son or daughter wants to play with you. By the time they are 10, they have their social circle built up. You also want them to have a circle (na unsolicited advice from me), as you don't want them to grow up all alone with none but their parents.

To answer: Yes, I am trying as much as possible I can (and he can) with each other.

It's a really great idea! How much for all the parts?

All the 6 boards with mic and speakers set me back by $250 Canadian. And the 3D prints are $17 a piece.

Very cool, I made a similar walkie talkie style program. https://gitlab.com/here_forawhile/terminalphone

I didn't realize a esp could run the tor binaries. I may have to dive into seeing if I can get it running on one now!

Cool project thanks for sharing.

Looks like, Tor may be an overkill for this project - according to Claude. That said, it advised there are several things we can borrow from your project: 1. Opus at 16 kbps 2. The voice-message model as a saved voicemail 3. In-call text chat 4. PTT chime

I may borrow the Opus, as I now send uncompressed PCM. May consider voicemail and chat (this may kill the joy, though - going away from ham-like experience).

Thank you for sharing your project, again.

Opus has incredible compression rates with high intelligibility I recommend if bandwidth is an issue...a few mild voice effects like static could be fun for the kids to make it seem like it's a real ham transmission, opus makes that easy.

It may be confused with what the voicemail was. Nothing actually gets saved like a voicemail, still destroyed after playback...I found record then send was the only way to overcome the latency of TCP and Tor.

Your setup is far more streamlined for lower latency coms for sure

Thanks! I was thinking about "static" as well but thinking about these kids who have no idea about this noise may just unnecessary complain. :-)

Nice! I'll check this over the weekend and see what I can borrow from Tor perspective. Thank you so much for sharing.

Where can I buy 5 units?

I bought all the units from here: https://itead.cc/product/open-nextion-2-8-genius-series-esp3.... Flashed them with custom and printed the boards.

Reply on news.ycombinator.com