Phone Keypad Hacking: Part 4

So when part 3 of this series turned out to be a bit uneventful, I wasn’t expecting a grand finale with fireworks. I was right about it being more difficult though.

Through numerous failed attempts I was running into trouble isolating the signals between the rows and columns. Everything was getting connected in one big circuit. Then I realized it was a perfect place to use diodes! Each button needed 2 though; one for its connection to the row and one to the column. I have a bunch of 1N4148 signal diodes so I wired everything up.


Although the Fritzing is using a different board than in the implementation pictured above, it’s much easier to follow the wiring…

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This obviously is a lot more complicated circuit than the examples in part 3 of this series. It was a success at what I set out to do though and it works great with my custom keypad code. I’ve also added the actual Fritzing file for this circuit to the repo.

I’m glad I continued down this path with keypad experimentation. I learned a lot. In the beginning I was wondering why the keypads you can buy these days work the way they do and not how I had wired up the old phone keypad to function. Turns out what ended up being a simple solution for me was due to how the old phone keypad made its connections mechanically inside the device. The keypad solutions I showed in part 3 are much easier to create as I’ve now proven by recreating the circuit above.

I’m still curious if I could wire up the old phone keypad to work with the Arduino Keypad library. I guess if I ever get my hands on another old phone, I’ll have to continue with a part 5 of this series.

Fidget Spinners

I made a couple of fidget spinners out of wood, screws, and a couple of 2 cent coins from Spain. The bearings came out of old Rollerblade wheels. Even after cleaning up the bearings, neither one spins very well, so I think I need to get some ones before making more spinners.


This was a good excuse to buy a Dremel, which I’ve been wanting for a long time. Awesome tool to have. I didn’t buy it until I’d already cut out the basic shapes and done some basic sanding though. The next batch of spinners will be much easier with the Dremel available for the entire process.

Bloodline’s Final Season

When I checked out Bloodline in season 1, I wasn’t expecting much. Season 1 and 2 were great though. Season 3 is right around the corner…

I wonder how many people missed where it says “The Final Season” at the end. I wish more TV shows would call it quits after a few seasons. Far too many drag on and on.

Knowing this will be the end has me even more excited to see what happens. Unfortunately it might be awhile before I get to watch it because I need to watch season 2 of Sense8 and House of Cards is released at the end of the month as well. I’ll only be home for about 2 days over the next 2 weeks, so there won’t be much time in front of the TV.

HackerBox #0018 – Circuit Circus

It’s not often an online ad catches my eye, but when I saw one for HackerBoxes, I clicked through. I’ve enjoyed Adafruit’s quarterly subscription service AdaBox and wondered if this was similar.

The HackerBoxes look lower quality, but are cheaper ($44 compared to $60, both with free shipping) and ship monthly instead of quarterly. The previous boxes listed on the site looked neat and sell for $59 before shipping so it seemed like a pretty good deal. I really like the idea of having something new to tinker with each month instead of only 4 times a year. I signed up and was surprised to get a shipment notification for the most recent box.

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This box is based around a little Transistor Tester kit you build. It also comes with a variety of extra electronic components that help go through a series of tutorials and aid in experimenting with circuits and the tester. If this box is any indication, I’m going to enjoy these each month.

It took me a couple of hours to assemble and solder the tester kit. I recorded it (had to stop twice to recharge the GoPro battery) and ended up with over 100 minutes of video! Nobody wants to watch all of that, so I cut out some empty space and sped it up to 20x.

Now I have a cool test device built by hand…

Link Dump 2017/05/17

Going to Bulgaria

Heading to Sofia, the capital of Bulgaria, for a team meetup. It’ll beat out Budapest, Hungary as the farthest east I’ve traveled.

There is a 7 hour time difference from the Eastern time zone, so it’ll be interesting to see how jet lag affects me. Since it’s a +1 day trip, I won’t be going to bed (maybe a nap or two on the flight across the pond) until Wednesday night local time. Usually staying up through the travel night and all of the next day helps to reset my internal clock.