• Added a function generator

    Christoph • 06/01/2022 at 21:05 • 0 comments

    It was time to buy a function generator, and of course it had to go into the rack:

    The power tools at the bottom had to move to a different place, but I didn't really need them on the rack so that's probably fine.

    Now that I have two SCPI capable devices on the rack, it's probably time for a little network switch...

  • Temporary cable management

    Christoph • 12/28/2020 at 18:36 • 0 comments

    I usually build breadboard circuits on IVAR's top shelf. They almost always require some sort of power supply cable, USB, scope probes and other stuff hanging from the sides and quite often things get pulled out by the weight of a cable. I needed to come up with some sort of cable management, and I wanted something that is easy to obtain, install and use.

    A quick tech screen (= ask in hack chat and get tons of silly ideas back) revealed plastic binders. They're cheap, can be bought in any office supply store, and can be cut to the desired length and stapled to the rack:

    What you seen in the image is a ring binder with 16 mm diameter, and it's almost a bit too loose - but it works very well. 14 feels a bit better, and 12 mm is too small to be useful. The edges of those circular "flaps" are quite sharp and slightly "bite" into the cable for more grip. That might sound a bit dangerous but no cable has been damaged so far.

  • New PSU

    Christoph • 01/02/2020 at 08:30 • 0 comments

    The ATX PSU I had installed previously was moved to my 3D printer, so I needed a new PSU for IVAR. I looked for a small one that wouldn't occupy too much space and luck was on my side - it fits next to the scope:

    The PSU is a PeakTech 6227, 0-60 V, 0-6 A.

    I printed a bracket to keep it from being push back when I plug in cables:

    I only printed one of these to go behind the PSU's back feet since the front can't move sideways anyway.

    OpenSCAD and STL files for the brackets (DS1054Z, PeakTech 6227) are in the project files section.

    In general, this is what I have in my hack rack (from top to bottom):

    • Scope
    • PSU
    • Powered USB hub
    • small box with Multimeter, Bus Pirate, OpenLogic Sniffer, cables and probes
    • large box with tools (tweezers, pliers, screw drivers, hex keys, cutters, ...)
    • large box with a soldering iron and soldering supplies (solder, desoldering wick, flux gel, solder paste, kapton, tips, ...)
    • Rework Station
    • Power tools and other large stuff in cases like hex wrenches, more screwdrivers, cordless drill, and a rotary hammer

    There's still room for another small box (currently there's a cutting mat in that space) and I'm not sure what exactly to put there. Maybe finer tools that I don't want to be thrown around like the more robust stuff.

  • New scope mounting brackets

    Christoph • 04/22/2019 at 21:36 • 3 comments

    Made 3d printed mounting brackets for the scope. They fit quite nicely:

    They were easy to design, print and install and the scope doesn't move at all any more. Just what I needed.

  • More for the top floor

    Christoph • 01/26/2019 at 22:03 • 0 comments

    New in the top floor:

    • ATX power supply
    • multi socket
    • powered USB hub
    • junction box (supplies power to ATX PSU, multi socket and scope)

    PSU is not really connected yet (apart from mains). Here's the multi socket:

    It has 3 outlets, two if which are used for the RPI's and USB hub's wall warts. The hub is installed towards the side because that was simply the easiest thing to do without having it stick out from the front. Yes, the picture quality sucks, but it does the job:

  • RPi flap and scope mount

    Christoph • 01/21/2019 at 21:00 • 0 comments

    I found a piece of scrap wood that neatly fits between into the narrow vertical side space. Installed it with a hinge and added an RPi:

    The RPi will be in my local WiFi and grant me access to the scope's LAN connection. It will probably be "closed" during normal usage, but I can open the RPi flap and add stuff for testing if I desire to do so.

    The scope mount is probably too simple, but it does the job quite well. Two pieces of a cable channel with a cutout, screwed to the front, for the scope to "slide" in, and a piece of pipe to keep it from sliding to the back:

    Here's a picture with the scope, from behind:

  • castors and racks

    Christoph • 12/19/2018 at 22:12 • 0 comments

    The individual IVAR shelves are held in place by four pins that go into holes spaced by about 32 mm. That's one IVAR height unit (HU). A few examples that fit quite nicely:

    The holes also make it easy to build hinges for temporary side-racks. I have some ideas for that. 

    I removed a lot of the stuff that was in there and rearranged the shelves a bit:

    From top to bottom:

    • 6 HU: Scope
    • 5 HU: undecided, might place SAMLA boxes there. Either one large box or two of the smaller ones fit nicely.
    • 5 HU: undecided
    • 4 HU: Power (ATX PSU)
    • 7 HU: Rework station. This doesn't have to be in a good height for working with it since I'll probably take it out and place it on a table for soldering.
    • the rest at the bottom: power tools and large hand tools. I'm not sure if I want them in this rack, but I don't know where to place them otherwise.

    The X-shaped thing in the background is supposed to make the rack stay upright, but it's also blocking access from the rear. However I think I'll want to be able to access the rack from two sides. It will have to go and be replaced with something else.

    At the bottom I Installed a base plate (MDF) and four castors. They don't turn freely though and sometimes get stuck on a mounting screw's head. I might change them for larger ones (will never happen I guess), but this will do for now:

  • Getting the scope into my wifi

    Christoph • 12/18/2018 at 22:02 • 0 comments

    I want to mount my Rigol DS1054Z scope to the rack. That alone won't be too hard, but there are two complications:

    • taking screenshots from the scope is necessary for many projects every now and then. I hate using a USB drive for that.
    • The scope has a LAN connector, but then the whole thing would either need to be plugged into different sockets every time I move it, or I'd have to connect it to my laptop. I hate my laptop's LAN connector.

    So I decided to add a Raspberry Pi (3B+) to the scope, to give it a wifi interface. That, however, wasn't the easiest thing for me because my networking experience ends at "install pre-configured router, get cat pictures". The devices involved are:

    • wifi router with DHCP
    • laptop in wifi
    • RPi in wifi, plus wired LAN interface)
    • scope with wired LAN interface

    Primary goal: get screenshots from the scope to my laptop over wifi.

    After some discussion about the right approach in the hack chat and on stack exchange (https://unix.stackexchange.com/questions/489232/connect-lan-device-to-wlan-using-a-raspberry-pi), I've finally found a working solution (thanks to @Ted Yapo ).

    Network setup

    Preparation of the RPi

    1. a fresh install of raspbian stretch lite 2018-11-13
    2. In the SD card's boot partition:
      • place a file called ssh to enable ssh
      • place a wpa_supplicant.conf, it will be copied to /etc/wpa_supplicant during configuration
    3. edit /etc/dhcpcd.conf to have a static IP for eth0, in a subnet different from the wifi router's. My dhcpcd.conf for eth0: 
      interface eth0
static ip_address=192.168.220.1/24
static routers=192.168.178.1 
    4. enable IPv4 forwarding:
      • uncomment the following line in /etc/sysctl.conf 
        #net.ipv4.ip_forward=1
      • apply change: 
        sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward" 
    5. reboot 

    Preparation of the scope

    Configure static IP in the new subnet:

    Preparation of the router

    Add a routing rule to the new subnet via the RPi's wifi interface

    Preparation of the laptop:

    Nothing network specific, I just installed the ds1054z python package. See https://hackaday.io/project/7691-ds1054z-python-package and https://pypi.org/project/ds1054z/.

    Taking a screenshot

    Now iIt's easy: open a terminal on the laptop and execute

    ds1054z save-screen --overlay 0.6 192.168.220.2

    In my network this takes about 4 seconds. The result is placed in the current working directory and would look like this:

    The screenshot with my scope's IP configuration was taken with the same method, so you get menus as well - whatever you see on the real screen.

    Why an RPi?

    • I had one and didn't have to buy any other hardware for this
    • The RPi has SPI, I2C and other interfaces on the expansion header, which might be a good addition to the scope's surroundings during prototyping. It's also quite convenient to use since I can ssh to it with my laptop, which can now also talk to the scope. This opens quite a number of possibilities.

    So one more device to add to the rack.