I listened to my first episode of “The Amp Hour” podcast as I drove from California to Texas on my way back from a summer internship at Sandia National Laboratories back in 2010. Now, that I have found myself commuting two hours everyday I started listening to the show again. Boy has this show come a long ways. Congratulations Chris and Dave! Keep up the great work.
I have had this post in draft for well over a year but I decided that even though it is grossly incomplete I would go ahead and make it live with hopes that I would update it as I come across episodes that peak my interest. With that said, here are some of my favorites that I have kept track of. Personally, I found that I prefer the episodes with guest interviews.
- The Amp Hour #115 – Watcher of Wraithlike Walls (An Interview with Dr. Greg Charvat, creator of the coffee can radar)
- The Amp Hour #133 – Tenacious Transistor Teacher (An Interview with Ron Quan, author of “Build Your Own Transistor Radios”)
- The Amp Hour #161 – Gifted Grimgribber Grokker (Interview with Michael Ossmann, founder of Great Scott Gadgets)
- The Amp Hour #144 – Hoodied HP Hijinks (An Interview with Bob Davidson)
- The Amp Hour #147 – Absorptive Augmented Actuality (An interview with Jeri Ellsworth, founder of Technical Illusions)
- The Amp Hour #149 – Purple PCB Philosophy (An Interview with James “Laen” Neal, founder of OSHpark)
- The Amp Hour #171 – Snell Solisequious Scientist (An Interview with Forrest Mims, author the Radio Shack “Getting Started in Electronics” and “Engineer’s Mini-Notebook” series)
- The Amp Hour #179 – (An Interview with Dr. Greg Charvat, author of “Small and Short-Range Radar Systems”)
- The Amp Hour #180 – Multi-talented Meter Maker (An Interview with Dave Taylor, designer of the Fluke 8060)
- The Amp Hour #185 – Zoppa Zumbahlen Zateticism (An Interview with Hank Zumbahlen of Analog Devices)
- The Amp Hour #214 – Recurring RF Remontados (An Interview with Dr. Greg Charvat and Michael Ossmann)
- The Amp Hour #222 – Zany Z80 Zygology (An Interview With Bil Herd, designer of the Commodore C128!)
If you are looking for other high quality podcasts to fill your commute and headphones may I also suggest Elecia and Christopher White’s electronics podcast “Embedded”; and Steve Gibson and Leo Laporte’s security podcast “Security Now!”
I’ve never been one to go all out with winter holiday decorations but here is a photo that I took that I have been using for years as my computer background this time of the year. I took this photo cutting through the Texas Tech University campus in Lubbock, Texas at the end of a group bicycle ride. There are others in the series but I don’t think they are published at this time.
Visit my flickr page to download the original (3008×2000) if you would like to use it as well. I linked to a nice page that will let you pick the actual size you would like to download.
After hearing proXPN marketed by Steve and Leo on the TWIT “Security Now” (SN) podcast for several months I decided to sign up for the service and take advantage of the SN promotional 50-percent off discount. By the way, if you have not been listening to the Security Now podcast or if you have never heard of it I encourage you to check it out. I had trouble connecting to the proXPN servers using the provided client software on Macintosh OS X 10.9.5 (other versions of OS or client were not tested) so I created a set of configuration files so that I could use an unbranded version of Tunnelblick.
When I realized that the proXPN OpenVPN client software was simply a rebranded version of the popular OS X OpenVPN client Tunnelblick I used the Tunnelblick instructions for removing rebranded versions of Tunnelblick. I then installed the standard Tunnelblick and attempted to configure it using Mark Lai’s instructions for using proXPN with Tunnelblick. After doing a few basic tests I confirmed that I could use proXPN’s service on my Macintosh running OS X 10.9.5 and Tunnelblick.
I wanted to keep all, or at least most, of the options/features offered by the proXPN client but using the standard non-branded Tunnelblick. By evaluating the OpenVPN documentation and the logs produced by OpenVPN packaged with Tunnelblick I decided to make a few modifications to the OpenVPN configuration files and to develop a set of configuration files so that I could utilize the various ports, servers and locations offered by the proXPN service. These configuration files utilize several security options documented by OpenVPN and do not utilize any up/down scripts supplied by proXPN. You may download and submit bugs/features against these configuration files at my github page. Installation instructions are provided there as well. These configuration files include the primary and secondary addresses off all the locations and will attempt to connect on ports 1194, 443, 80 and 8080 in that order. See screenshot above for what Tunnelblick looks like after these configuration files are installed.
I would also like to point out that I tried a competing paid ($9 USD) OpenVPN client for OS X titled “Viscosity.” Viscosity does not appear to be updated as often as Tunnelblick. For a security application this is a bit of a concern to me. Viscosity is not open source like Tunnelblick. Viscosity has a few bugs at the moment that prevented me from being able to use or test the product. These bugs prevent a user from importing existing OpenVPN configuration files. When I attempted to manually create and modify configurations from within Viscosity I was not able to connect. After getting Tunnelblick to work and spending some time on Viscosity I lost interest and patients. I have some UI complaints against Tunnelblick but they are mostly the same with Viscosity so I really was not that motivated to get Viscosity to work.
As a whole I feel pretty disappointed in the state and availability of OpenVPN clients for OS X but I’m happy I found a solution that appears to work well for me. I have decided to stay with paid/premium proXPN service for the next year instead of bailing out during the 7-day grace period. Hopefully the proXPN quality of service will overcome my OpenVPN client issues. I still have clients to configure for iOS 8, Arch Linux and Windows 7. By the time I am done configuring all of these clients, I expect to have a decent impression of how OpenVPN clients are implemented across various popular operating systems.
I’ve been using KiCad on and off for a few years now. I like KiCad reasonably well but it doesn’t always play well with Mac OS X so I usually run it in a Linux Virtual Machine. Here are the install steps for Arch Linux assuming that the X Windows System, graphical interface environment, is already installed.
# Update Pacman and download dependencies sudo pacman -Syy sudo pacman -S cmake bzr wxgtk glew # Configure bzr username... # Even though I would prefer not to... bzr whoami paretech # Change into Arch User Repository download directory # or wherever the download should go. cd ~/aur # Download Bzr Tools (includes the necessary Bzr Patch plugin) curl https://aur.archlinux.org/packages/bz/bzrtools/bzrtools.tar.gz --remote-name tar -xzvf bzrtools.tar.gz cd bzrtools # Inspect PKGBUILD first! makepkg sudo pacman -U bzrtools*.xz # Download Kicad AUR and name file same as remote name curl https://aur.archlinux.org/packages/ki/kicad-bzr/kicad-bzr.tar.gz --remote-name tar -xzvf kicad-bzr.tar.gz cd kicad-bzr # Inspect PKGBUILD first! makepkg sudo pacman -U kicad-bzr*.xz
That’s all there is to it on Arch. Good luck on your next PCB and Happy Hacking!
A while back I took opportunity to hack together a piece of Assistive Technology (AT) for a good friend of mine using a damaged pair of Apple Earphones with Remote and Mic. The first version, pictured on the right, is constructed with a three button array found on ebay.
The second version, pictured at the bottom, is constructed with large arcade buttons from Sparkfun and a custom enclosure that I made with sheet metal, a breaker bar and pop (blind) rivets. This version should be easier to use than the first as it has larger softer buttons, less dangling wires and a case that can withstand being squished between an electric wheel chair and a door frame.
If you are interested in what is inside the Apple Earphone controller, there is a wonderful tear down post.
When I was an intern at Sandia National Laboratories I was introduced to the concept of using virtual machines to sandbox my projects. I have found this to be very helpful for many software experiments and development environments. I even use virtual machines to run my day-to-day Linux install. Here I give my notes on how to use Virtual Box to run an Arch Linux guest install on Mac OS X. Once a base install is complete it’s easy to make snapshots and spin up and destroy clones from the base install as needed.
Create New Virtual Machine
- Download Arch Linux ISO Live CD
Create VirtualBox Disk Image (VDI) with desired settings.
Load the Arch Linux ISO as a CD/DVD image and select the “Boot Arch” option when the live CD boots.
Partition the drive(s)
# gdisk /dev/sda
- Use the n command and values (above) to create partitions using gdisk.
- Print the the gdisk partition table with the p command.
- Write the gdisk partition table with the w command.
Install and Configure System
# Format Partitions mkfs.ext4 /dev/sda1 mkswap /dev/sda2 mkfs.ext4 /dev/sda3 # Mount Partitions mount /dev/sda3 /mnt mkdir /mnt/boot mount /dev/sda1 /mnt/boot swapon /dev/sda2 # Configure Mirrors # Install Base System pacstrap /mnt base base-devel linux # Generate File System Table genfstab -p /mnt >> /mnt/etc/fstab # Set hostname echo 'myarch' > /etc/hostname # Change Root Directory arch-chroot /mnt # Configure language echo LANG="en_US.UTF-8" >> /etc/locale.conf echo LC_COLLATE="C" >> /etc/locale.conf echo LC_TIME="en_US.UTF-8" >> /etc/locale.conf echo "en_US.UTF-8 UTF-8" >>/etc/locale.gen locale-gen ln -s /usr/share/zoneinfo/America/New_York /etc/localtime hwclock --systohc --utc # Generate Ram Disk mkinitcpio -p linux # Install and Configure Bootloader pacman -S syslinux gdisk syslinux-install_update -iam # Exit CHROOT, Unmount Drives and Reboot exit umount -R /mnt reboot
The following isn’t really intended to be executed as a script.
# Setup Network systemctl start dhcpcd systemctl enable dhcpcd # Virtual Box Guest Utilities # https://wiki.archlinux.org/index.php/VirtualBox#Arch_Linux_as_a_guest_in_a_Virtual_Machine pacman -S virtualbox-guest-utils --noconfirm modprobe -a vboxguest vboxsf vboxvideo echo vboxguest >> /etc/modules-load.d/virtualbox.conf echo vboxsf >> /etc/modules-load.d/virtualbox.conf echo vboxvideo >> /etc/modules-load.d/virtualbox.conf groupadd vboxsf systemctl enable vboxservice systemctl start vboxservice # X Windows System pacman -S xorg-server xorg-server-utils xorg-xinit xterm ttf-dejavu --noconfirm pacman -S awesome # User Configuration pacman -S sudo --noconfirm # use visudo to add under "User privilege specification" before # using sudo as # Replace user_name with desired user name. useradd -m -g users -G optical,power,storage,vboxsf -s /bin/bash user_name chown root.vboxsf /media # Set password using "# passwd " # Set root password using "# passwd" # Update Packages and System pacman -Syy pacman -Syu
Per User Config
Configuration for users other than root.
echo /usr/bin/VBoxClient-all >> ~/.xinitrc echo "exec awesome" >> ~/.xinitrc ln -s /media/sf_share_name/* ~/share_name
At one point I was trying to install linux wireless drivers and since I didn’t have access to an ethernet connection I decided to transfer my driver to the computer in question via a USB thumb drive. But what do you need to do after plugging in the USB disk drive to the Linux machine in order to access the data?
Before connecting your USB device, execute the list block devices “lsblk -f” command. Then, connect your USB storage device and execute an “lsblk -f” command again. Notice anything different?
In my case I observed a new block device filesystem named “sdb1″ and its own UUID. Using the UUID, one can mount the USB device by executing “mkdir /mnt/usbdrive && mount -U YOUR_USB_DEVICE_UUID /mnt/usbdrive” as root. Take care when typing these commands, unlike most Windows/Microsoft systems I have used, *nix systems are case sensitive.
When you are finished with the device, you may “un-mount” it by executing “unmount /mnt/usbdrive” as root.
That was easy!