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Ask HN: Most interesting tech you built for just yourself?

1901 points l2silver | 3 comments | 27 Apr 23 15:04 UTC | HN request time: 0s | source

Maybe you've created your own AR program for wearables that shows the definition of a word when you highlight it IRL, or you've built a personal calendar app for your family to display on a monitor in the kitchen. Whatever it is, I'd love to hear it.
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sriram_malhar ◴[28 Apr 23 06:47 UTC] No.35738249[source]▶
My MIL is 93, and the only tech she can really deal with is turning on the radio and TV and changing channels.

She is fond of music from old classics (from the 60's and earlier), so I hooked up a Raspberry PI with an FM transmitter and created her own private radio station. She tells me what songs she likes and I create different playlists that get broadcast on her station. It preserves the surprise element of radio, and there is nothing in there she doesn't like.

The tiny FM transmitter is surprisingly powerful. Her neighbours (of similar vintage) are very happy too, so their requests have also started coming in :)

EDIT: I wanted to add that I am the UI ... she doesn't get to choose the playlist. To make my life easier, I just created different playlists for different times of the day ... calm/spiritual/slower numbers in the early and late hours, peppy during the late morning and evening etc.

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LeoPanthera ◴[28 Apr 23 07:14 UTC] No.35738432[source]▶
What transmitter did you use?
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sriram_malhar ◴[28 Apr 23 07:32 UTC] No.35738533[source]▶
I forget. But just search for "kit FM transmitter". I'd fully intended to build a "proper" transmitter, and was keenly disappointed that you could just buy a cheap single-chip board.

Nowadays you don't even need that. You can turn the RPi itself into an FM transmitter. Search "how to FM broadcast on raspberry pi"

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idonotknowwhy ◴[28 Apr 23 07:51 UTC] No.35738657[source]▶
You do still need that. The broadcast from gpio thing is very low quality and produces square waves which interfere with everything
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1. hcrean ◴[28 Apr 23 12:53 UTC] No.35740687[source]▶
Pico caps and appropriate impedance miss-match can be used to round-off square waves.

But yes, if you look at high-speed Pi GPIO with a Rigol it looks more like an EKG readout than the thing you might see on a logic analyser. Smoothing it enough to feed a line-amp is very lossy.

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2. megous ◴[28 Apr 23 14:01 UTC] No.35741360[source]▶
You might want to improve your probing technique, then. :)

GPIO's usually looks quite squarey if you don't introduce parasitic reactances into the circuit with your test setup.

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3. hcrean ◴[28 Apr 23 19:41 UTC] No.35746144[source]▶
Pi for audio frequencies is lovely and square, Pi at radio frequencies has distinct rise and fall and "just taking a moment to think about it" segments.

A spectrum analyser has probes!?!? This might be where I am going wrong... But the bench scope is largely in agreement about the distinct phases of a cycle at RF freq.