All posts for the month October, 2013

Click below to vote for dijit to win a Chase Mission Main Street grant, and help dijit launch a hackerspace!


With this grant dijit will open a hackerspace in Pittsburgh, PA, and establish a sustainable model to grow the hackerspace/makerspace movement across the US.

The hackerspace, Hack Local, will offer access to tools and equipment for members to develop their projects and ideas. Hack Local will be more than just another hackerspace. We want to build a community movement that encourages creativity, innovation, and an entrepreneurial spirit among members. Through dijit, Hack Local members will have both online and local retail venues to market their products, as well as access to discounted supplies and components for all of their projects. Hack Local will offer classes and instruction to members and the general public, and encourage the creation of mini-hackerspaces in our surrounding communities. Hack Local will also provide a hub for collaboration among hackerspaces to share information and resources. Other proposed projects include an electronics re-use and recycling program, where usable parts will be salvaged from discarded electronics for use in hackerpsace projects.

We have a lot of exciting projects in the works, but we need your help to get them off the ground! Spread the word and vote for dijit in the Chase Mission Main Street grant program. Help dijit start a hackerspace!





When I saw this beauty tucked in the back corner of an antique store, under a stack of other items and sporting decades of dust accumulation, I could not resist. After some small talk with the shop owner  about its condition, where it came from, etc., I negotiated a fair price and loaded it up. I immediately began scouring the interwebs for any info on this beauty and was pleasantly surprised to find a wealth of information from antique radio and tv forums. This particular set was marked TS4-J on the chassis, and rolled off the production line in late 1949.

Below are a few examples of great discussions and write-ups on rebuilding these old 7″ sets:

After reading through these posts I was able to determine that most of the original paper/wax capacitors had already been replaced, and judging by their replacements this was done sometime in the late 1960’s. The original ballast tube was still in place which, based on the voltage readings (and the smell of burning cats), I gathered was something that would need to be replaced. Again I found several great write-ups on how to replace the original ballast tube with modern-day parts to make the circuitry more-betterer. I found diagrams and schematics, including a pinout for the ballast circuit that made my job even easier:


TS-4H-Filament stringsvt71-ballast-diagram  vt71-ballast-pinout

With some fresh capacitors and resistors from digikey I was able to wire up a replacement ballast that would mimic the correct voltages and provide a slow start-up the old vacuum and CRT tubes love.

vt71-4     vt71-3

Here you can see the parts that I temporarily wired up and taped to test the circuit. I turned the brightness knob all the way down and slowly applied power. As I did this I wondered how many years, or maybe even decades, had gone by since these components had been powered up. The set slowly came to life and the soft glow of the tubes created a geeky delight.

After confirming the replacement ballast was functioning properly, I then took to mounting the components in a way that would conceal them in the original ballast tube.

vt71-5  vt71-6  vt71-7

vt71-8  vt71-9

The end result was a replacement ballast that provided the appropriate voltages without changing the overall look and feel of this classic motorola set. I was able to play with the adjustment and tuning knobs and watched the picture tube flicker and dance in response. The set would not display an image on the CRT, even with a VCR and a 300ohm RF modulator , so I have some more work ahead to determine if this set is indeed fully functional again.