Author Archives: Jaimesh

About Jaimesh

I'm a fourth year Electronics and Communications Engineering Student from the University of Bristol. I love hacking all sorts of things, pushing their capability to the limit of their design and beyond.

The TwitALU as a display piece

The TwitALU has gained massive interest from it’s exposure on several technology blogs including the famed It has also been well received on it’s outings to the DigiMakers Raspbery Pi boot-camp events at @Bristol.

Members of the Electronic and Electrical Engineering department will be glad to hear that the TwitALU is finally being mounted on a wall in the Merchant Venturer’s Building and will soon be up and running for all to play with :). See if you can work out where it is!

TwitALU Hanging Out

TwitALU Hanging Out


It’s done!

The TwitALU in it's entirety.

The TwitALU in all its glory..

It’s been a long time since we’ve posted but the TwitALU is finished! It has already been shown off at the University of Bristol Open Day and the DigiMakers event at At-Bristol (review).

After the break are a few videos and photos of the TwitALU in action!

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More Arrivals

Today, I’ve had an eventful day – not only have I received my small, test order from RS Components, I have also received the Nixie tubes and power supply boards. We chose to order 16 Nixie tubes – five for each 8-bit input register and six for the output register. Separate flyback boost converters are needed for the Nixie tubes as they operate at 120V which we are unable to supply directly.

I have yet to power up the tubes, but I’ll be sure to post some pictures when I do – they should give the TwitALU that vintage feel that we’ve been after. Continue reading

Constructing the PCBs

Twitalu v0.1 PCBs

Twitalu v0.1 PCBs

After a very exciting unboxing of the first ever PCBs that Jeremy and I have ever ordered, I started the task of constructing and populating the boards.

The first task was to break the tabs that we had created to avoid PCBTrain’s pricing. This proved to be really easy with a guillotine. The edges of each board were then sanded down on a belt sander to smooth out the tabs. Continue reading

Here Come the Relays – Clickety Clickety Click…

1-Bit Relay Adder

1-Bit Relay Adder

Now that we have a Twitter Arithmetic Logic Unit, we can begin the fun stuff! Although 7400 logic is a classic platform for logic circuits, there is still an air of mystery about what goes on inside those little black chips. The advantage of 7400 logic is that it’s incredibly easy to use and the variant that we’ve chosen (74HCT) is super speedy.

But don’t worry, the Twittithmetic Logic Unit (TLU) isn’t just a PCB with a few black boxes. The core aim of the TwitALU project is to make computing rhythmically audible and visually entertaining. This is where the adder module comes into its own.

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SmartNixie Vacuum Tubes!

We’ve had great fun using the Raspberry Pi’s I2C bus and Port Expanders to talk to all the registers in the system and to control the ALU. It’s such an easy to use protocol –  writing to 8 pins of a Port Expander is as selecting the Port Expander and sending it a byte of data.

SmartNixie IN12. Credit:

SmartNixie IN12. Credit:

However, Port Expanders aren’t the only I2C device around. You can find all sorts of devices like LED dimmers, LCD drivers, Data Converters (DAC/ADC), Memories, Clocks and Audio synthesisers to name just a few.

Monochrome 128x32 I2C OLED graphic display. Credit:

128×32 I2C OLED graphic display. Credit:

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