#bug does electronics

[insectoid5]

Figures.

So, I made the effort to (more or less) thoroughly vacuum the car I drive last week, and only today actually drove it somewhere. And the freaking 12V socket, which my dash cam and Bluetooth transmitter both run off of, suddenly doesn't work.

Sonuvabitch.

[insectoid5]

@blunaowl replied to your post “I got myself a little toy at the bookstore this afternoon...”:

SHOW ME THE FADING TARDIS

Ask and you shall receive!  This video and the photos are new, taken with my Canon Elph 170, rather than the crummy ones I took with my old iPod touch 4 way back in 2013.  The text below, describing how I did it, is mostly derived from the Facebook post I wrote.  I’ll put that below a read more, since it’s kind of technical electronics babble and may not be for everyone. 😅

Sherman, set the WABAC machine to summer of 2013.  It was late July, and my mom and I (at the encouragement of her friend) had started watching the new Doctor Who, and we were over a season into it.  On an outing, we just happened to stop at a B&N bookstore, where I saw this cute light up TARDIS, and happily bought it.  It’s about 3″ tall, including the light, and 1.5″ on a side:

This is with the white LED, of course; the blue one looked MUCH more out of place.

I was initially disappointed to discover that its illumination was a) with a blue LED, and b) static, either on or off with the switch on the bottom.  So I opened it up and, finding a sufficient amount of extra space inside, started planning a hack.

I didn’t actually get around to serious planning until a month later, when I figured out how I might build an LED “fading” circuit with minimal component and power requirements.  So I did a Google search for circuit ideas, and what I came up with was this simple 555 timer circuit:

Yes, I drew this.  One of the perks of growing up with an EE is learning electronics and schematic drawing.

Besides the ever-useful 555 chip, only a few other components were needed: a capacitor to store charge (which helps create the “fading” effect); a potentiometer (variable resistor), to adjust the frequency (the speed of the fading); a general-purpose transistor; and another resistor for the LED (the blue LED came with one connected near the switch, I think, but I used a different value).  Finding all of these parts, except one, didn’t even require leaving the house (yet another perk of living with an EE), but I did have to find a 3 mm white LED.  (At Fry's, probably.)  This is the finished circuit, which I put together that Labor Day weekend:

The part number is vague, but the chip is definitely a Philips/Signetics NE555.  It was a numbering scheme often used by Hewlett-Packard for outsourced parts, so this was probably among the old parts salvaged by my dad from his work.

Assembling and soldering the circuit took me several hours, mostly because I am a perfectionist was being careful to not make mistakes.  Then there was the difficulties I had with the battery—or rather, batteries.  The toy TARDIS came with a single CR1632 3-volt lithium cell, with a metal contact on the side for the (+) and on the bottom for the (-).  To operate the 555 and LED, I needed at least 5 volts; the simplest solution to this was to use two CR1616 3-volt cells in series.  The problem was that the tab on the side (for the + terminal) would contact both batteries, making a parallel circuit.  So, I had to fabricate a new terminal that goes over the top of the cells, without touching the sides:

It looks crude, but it works.  Someone on FB suggested that I add a sound chip, but I wouldn't know what kind, and don't know if there's enough juice in 2 coin cells to run it... 😅

[bug-on-the-wire]

So, my dad's brother recently passed away. And among the things left behind, in storage, was this Commodore PET computer. It looked a lot worse than this, covered in dust and dirt. So I spent 3 hours today cleaning it up, knowing that my dad wouldn't have.

We don't know yet if the computer is functional - it's unlikely - but my dad and I will do our best to try and get it working.

[insectoid5]

Why do all of my hardware hacking projects seem to wind up involving knives and drills? 😅

[insectoid5]

You know, looking at the case fans that I have now... If I got some green LEDs of the right color green, and figured out how to yank the blue LEDs out of these fans, I wouldn't need to buy any new fans at all! 🤔

[insectoid5]

It seems absurd that my computer mouse, which is only 6 months old, would have the switch for the left mouse button wearing out.  (Especially considering my previous mouse lasted for *7 years*.)  So here I am with a packet of new switches, ready to replace it rather than buy a new mouse AGAIN.  Geez.

[insectoid5]

@olofahere reblogged your post and added:

PiGRRL? Like Raspberry Pi?

Yes, indeed!  It’ll be a lot like this one, except a bit bigger and with built-in sound.  (@kalikoke building that was what inspired me to build one, based on this.  I’ve been chatting with her about my progress, which is slow because of school-related priorities.)

[insectoid5]

Whoops... sorry about that.  I meant to come back after dinner and answer asks, but got carried away working on my PiGRRL Zero project.  By the time I’d had enough of sitting in front of a soldering iron for the night, it was laaaate.  So I’ll answer asks tomorrow. 😅