Not Not-a-Cyberdeck news

No news from Steve for over a month. What's he doing in there...?

Not Not-a-Cyberdeck news
My little portable monitor

Work on the mad computer has halted for the time being because my head's been all over the place. After decompressing slightly, I started easing myself back into electronics and 3D design again though. First up - my little portable monitor.

This started life as the screen mentioned way back in the first Cyberdeck post in November, and is a 7" thing designed for mounting in vehicles. It has HDMI, VGA and composite video inputs, and had been sitting in a pile of bits of things I started playing with and forgot about. I decided to turn it into a portable device after discovering little USB-C battery charger and protection boards, which I needed for another thing (making an original Retroflag GPi Case rechargeable).

I'd already modded the screen to take power from a micro USB socket, so there was a boost converter to get the 5V up to somewhere near 12V ready to go. Replacing the socket with the charger board was easy, and I had a battery ready to go from a junked phone. I'd also already done a load of measuring and design to make a bezel when I thought the screen would end up being in the Cyberdeck project, so I could hit the ground running with a case.

Circuit basics

As usual I started printing and assembling before I'd finished designing the case so there were some missteps - the position of the boost board, seen at the bottom of the photo, was a mistake because it was far too close to the edge - and the prints suffered a bit from warping at the corners. It's particularly noticeable on the back but it's on the front corner as well (see the toppermost photo).

Oof, that seam!

It all went together pretty well, thanks in part to using threaded brass inserts for the screws to go into (rather than just ramming them in and letting the plastic try and hold the thread).

Side view in progress

I hate clicky tact switches so I used this opportunity to replace them with something a little softer. They go into the divots with a leg either side of the central beam. The USB-C charge port took a bit of lining up but has ended up nice and solid. The switch cuts power to the driver board, because the normal power button is not going to stop draining the battery, however slowly that may be.

So that's that. I also did a similar job with the charger and boost board to make my transistor (and everything else) tester portable, but I don't have a photo of that ready. It's one of these though, with the same neon orange plastic to create a base, and it works really well. (Search for GM328A tester if you want one.)

One of these, yesterday

I also used that mad filament to create a faceplate for an upgrade to my power supply setup. I've had the case for a while with a different module and PSU inside, but wanted to go big with a boost/buck converter (ie voltages can be higher or lower than the source) and had a pair of decent quality Nvidia wallwarts I could use to feed each of the modules (my Nvidia Shield died a death and it turned out it wasn't its power supply after Nvidia sent a replacement for that).

Dual PSU

By having two separate PSUs inside the two modules are isolated from each other on the DC side of things, which is great - I can connect positive of one to the negative of the other and get an asymmetric ± supply of any voltage up to about 36V.

I made a thing to hold my cheapo oscilloscope as well, which you can see here where I'm testing an oscillator.

I'm trying to finish the filament

I found a stash of AS3340 chips while I was looking for something else and decided it was a shame to leave them in a drawer - these chips are a complete VCO on a chip (it's a synthesiser thing) - so I looked for a minimum viable circuit to use with them. When I found one on GitHub it had the PCB design with it, so I got some PCBs made at JLCPCB for next to nothing (it cost less than £6, delivered, for five of them).

I've not tuned the circuit yet, or had it output to anything other than my scope. That'll happen in due course.

What next? Well, a week off work, featuring a few days in London in well air-conditioned environments... oh, and the unused areas of Charing Cross. Hardware-wise, I'm gearing up for getting back to the Not A Cyberdeck as well as more messing about with synth circuits. Nothing certain yet.