Power supplies on the workbench

I’ve got a number of power supplies that I can use to supply power to the various projects that I’ve got on the workbench.

There’s the obvious wall power and a variety of wall warts of different voltages and current ratings. I’ve got wall warts and power supplies ranging from 5V all the way up to big chunky 28V power supplies.

A power strip mounted to the side of a bookshelf with a 5V wall wart power supply and flashlight plugged in
A power strip mounted to the side of a bookshelf with a 5V wall wart power supply and flashlight plugged in

For projects that require a beefier power supply I’ve got an unregulated power supply that gives me up to 30VDC or 25VAC. It doesn’t get used too often, but comes in handy when it’s needed. There are also a few 13.8V power supplies that I can steal from the radios in a pinch.

Power supply offering unregulated 0-30V DC and 0-25V AC
Power supply offering unregulated 0-30V DC and 0-25V AC

Most of my projects don’t have big current draws though, so more often than not, I’m just using batteries to power my projects. One that I use most often is a 12V battery pack made by wiring 2 quad C-cell battery holders together and putting a standard 3.5mm DC barrel connector on it.

A battery pack of 8 C-cells connected to a Sparkfun RedBoard
A battery pack of 8 C-cells connected to a Sparkfun RedBoard

DC barrel connectors can be easily attached to those snap connectors used for 9V batteries providing another power source (here’s one from Sparkfun if you don’t want to make one).

A 9V battery connected to a Sparkfun RedBoard
A 9V battery connected to a Sparkfun RedBoard

Some battery holders I have also use those snap connectors, so I can have battery power sources ranging from 3V to practically as high as I need.

Batteries in a variety of battery holders
Batteries in a variety of battery holders

I’m often using mostly used batteries pulled out of other things like TV remotes, smoke detectors, etc. Usually they still have plenty of juice left to power my smaller projects.

While charging up some old sealed lead acid (SLA) batteries pulled from my battery backup UPSs, I got to thinking about how I could put them to use as an additional power source. I’ve got plenty of three terminal voltage regulators that would provide the voltages that I’d need.

I sketched out block diagrams for a couple of possible concepts. One would switch between several different voltages but provide just a single output, while the second would provide multiple outputs and have toggle switches turn to each one on or off.

Block diagram for a potential battery powered power supply with a variety of switched voltages
Block diagram for a potential battery powered power supply with a variety of switched voltages
Block diagram for a potential battery powered power supply providing multiple voltages
Block diagram for a potential battery powered power supply providing multiple voltages

Probably wouldn’t do 3.3V, but the others would definitely be feasible. 12V would probably be just a direct connection to the battery rather than going through a voltage regulator. Since I’ve got 2 SLA batteries, I could even put them in series for a 24V source and give myself a wider range of regulated voltages.

Still in the concept stage for this and haven’t started building anything yet. Seems like it could be a fun project.

Hunkering down for Hurricane Ian

After plowing through most of Florida and causing much devastation as a Category 4 storm, Hurricane Ian is heading toward us as a much milder, but very large Category 1 hurricane.

NHC forecast track for Hurricane Ian, 30-Sep-2022 0500EDT

The tropical storm force wind field (yellow blob) is about the largest I can remember seeing from a storm. The forecast track for Ian has been shifting more east over the past few days after the storm crossed over Florida, giving it a chance to regain a bit of strength before coming on shore again. Good for us, but maybe not so much for places further north along the coast. Looking like Ian will make another landfall around the Pawley’s Island/Myrtle Beach area of SC.

Flooding is pretty much the main concern, and with a projected high tide of 9 feet, there’s definitely going to be some of that in the lower areas

Not expecting anything too serious to happen here at the house. Patio furniture got moved into the garage, and we’re set to deal with any extended power outages if that happens (hopefully not).

Xorg and a Barco monitor

I’ve added a nice big Barco MDCC-6230 6 megapixel monitor to my work computer. The monitor comes from a radiology diagnostic workstation that was being taken out of commission, so I managed to get the monitor and an nVidia Quadro P1000 video card to drive it.

Out of the box, I had a hard time getting Fedora to use the resolutions the monitor was capable of and it would only run the Barco monitor at 1024×768.

Thanks to the collective knowledge of the Internet, I figured out how to use xrandr to get the video card to drive the monitor at its full resolution (3280×2048) and arrange the displays the way I wanted them.

# Create a new display mode.  Modeline info came from the Xorg log file.
# (II) NOUVEAU(0): Modeline "1640x2048"x49.9  188.50  1640 1688 1720 1800  2048 2051 2061 2097 +hsync -vsync (104.7 kHz UP)
xrandr --newmode "1640x2048" 188.50  1640 1688 1720 1800  2048 2051 2061 2097 +hsync -vsync

# Add the new modes to the video card outputs connected to the Barco
xrandr --addmode DP-1 1640x2048
xrandr --addmode DP-2 1640x2048

# Configure the video card outputs
xrandr --output DP-2 --mode 1640x2048 --pos 0x0 --primary
xrandr --output DP-1 --mode 1640x2048 --right-of DP-2
xrandr --output DP-3 --mode 1600x1200 --pos 3280x848

Unfortunately, whenever I logged out or rebooted, the computer reverted to the original 1024×768 configuration. Getting the display configuration to persist across logins and reboots meant getting X Windows configured properly. It took a while, but I figured out a working set of xorg.conf configuration directives that worked (placed in /etc/X11/xorg.conf.d/10-monitor.conf).

Section "Device"
    Identifier     "Device0"
    Driver         "nouveau"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro P1000"
    Screen         0
    Option         "Monitor-DP-1" "Monitor0"
    Option         "Monitor-DP-2" "Monitor1"
    Option         "Monitor-DP-3" "Monitor2"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    Option         "Monitor-DP-1" "Monitor0"
    VendorName     "Barco"
    ModelName      "BDS MDCC-6230"
    ModeLine       "1640x2048"  188.50  1640 1688 1720 1800  2048 2051 2061 2097 +hsync -vsync
    Option         "PreferredMode" "1640x2048"
    Option         "DPMS"
    Option         "Position" "1640 0"
    Option         "DisplaySize" "327 409"
EndSection

Section "Monitor"
    Identifier     "Monitor1"
    Option         "Monitor-DP-2" "Monitor1"
    VendorName     "Barco"
    ModelName      "BDS MDCC-6230"
    ModeLine       "1640x2048"  188.50  1640 1688 1720 1800  2048 2051 2061 2097 +hsync -vsync
    Option         "PreferredMode" "1640x2048"
    Option         "DPMS"
    Option         "Primary"
    Option         "Position" "0 0"
    Option         "DisplaySize" "327 409"
EndSection

Section "Monitor"
    Identifier     "Monitor2"
    Option         "Monitor-DP-3" "Monitor2"
    VendorName     "Planar Systems"
    ModelName      "PX212M"
    ModeLine       "1600x1200"  162.00  1600 1664 1856 2160  1200 1201 1204 1250 +hsync +vsync
    Option         "PreferredMode" "1600x1200"
    Option         "DPMS"
    Option         "Position" "3280 848"
    Option         "DisplaySize" "432 324"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    Monitor        "Monitor1"
    Monitor        "Monitor2"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
    Option         "metamodes" "DP-2: 1640x2048 +0+0, DP-1: 1640x2048 +1640+0, DP-3: 1600x1200 +3280+848"
EndSection

The Xorg log tells me some of the configuration directives aren’t used, but everything works so I’ll leave it alone for now.

Now my work computer desktop has a total of 3280×2048 + 1600×1200 pixels (across two monitors) of workspace for me to do stuff in. I wonder if I can get Xorg set up so that the Barco gets used as a single monitor instead of two virtual monitors.

Returning to Southeast Linuxfest

Southeast Linuxfest returned to being an in-person event for 2022 after being an on-line event the last couple of years.

Confirmation that SELF 2022 was going to happen came a lot later this year than usual, so attendance and the number of exhibitors wasn’t as high as usual, but still pretty decent considering the announcement came about 6 weeks before the event. Not as many talks either, but the call for speakers came out with equally short notice and about the time that it normally ends. The talks were all pretty good though despite the short notice presenters had to submit their talks.

Beginning of my Twitter thread while at Southeast Linuxfest 2022

This year I shed my “Unofficial Official Photographer” role at SELF and spent my time being a much more relaxed volunteer helping out as room monitor for a few talks, and catching other talks that sounded interesting.

I really enjoyed the “Swap as a Service” talk by @q5sys. What do you do with older memory-dense server hardware? Make RAMdisks and export them over the network!

It was good to be back at SELF and seeing familiar faces again. Lots of new faces too. Looking forward to being back next year.

My SELF 2022 photo album.

A bin of slide rules

One of the finds from the 2022 Atlanta Hamfest that I’m most excited about is the bin of slide rules and slide rule books that Connie found at one of the flea market tables.

A bin of assorted slide rules and slide rule books
A bin of slide rules and slide rule books

There were 10 different slide rules and a total of 12 slide rules in the bin. Some of them were pretty basic slide rules, and some were more advanced with multiple scales, some of which I hadn’t seen before. These bring my slide rule collection up to 15.

I’ve made a first pass through the bin to check out the slide rules and jot down some notes about them. All of them are in pretty good condition, although one of them is missing the cursor. Two Keuffel & Esser rules, three Picketts, three Sterling, a couple very short pocket sized slide rules, and a little circular rule with some basic scales on it.

It will take me a while to research, photograph, and learn more about each slide rule. Should be a fun project.

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