Introduction

Over the years I have come across different giant projects. There is a Giant Arduino Uno, a Giant LED, a Giant Resistor ohmmeter, a Giant NE555 footstool and lately a Giant SD card. I’m not sure why people think is so interesting to upscale tiny objects from around there lab, I guess there are different stories and reasons. But now there is also the Giant Vacuum Tube Lamp and here is my story about it.

Inspiration

The other evening I was trying to get an overview of all our digital images that were spread all over the digital place. From old smartphones including online backup services that were about to expire or filled up, like Dropbox, Google Drive and OneDrive to different folders in different computers and backup hard drives to an old camera in a drawer. On an old hard drive I found some very interesting images taken longtime ago at a music festival with the famous, now dead, Danish musician Kim Larsen that I have heard on the radio since my childhood. In the background of the stage stood four vacuum tube models the same height as a person. They looked rather realistic with orange light simulating the filament heater and blue light simulating the fluorescence that can be seen in some power tubes. My guess is that they should look like EL34 power tubes typically found in guitar tube amplifiers. I remember that I thought they looked so cool and wanted to build something similar. But I never got anything done about it – until now.

When I saw the images again I got the same excitement and started to search around for the part that would define the rest of the design – the glass envelope. I was surprised to find many different products available. Typically used as a glass bell for displaying flowers or other creative things as an interior decoration. Most of them had a dome shape at the end without a tip resembling the exhaust tip on a vacuum tube. This was not a big problem because it looked a lot like the EL34 where the exhaust tip is hidden at the bottom of the tube between the pins. The dimensions of the glass bell gave me some dimensions to continue my work with the search for the rest of the parts. An EL34 measures 33.3 mm in diameter and is 98 mm high including the socket but without the pins. The closest I could come to this relationship, using the largest glass bell I could find, was one that had a diameter of 21.5 cm and a height of 52.5 cm. This gives an upscaling factor around 7 for both diameter and height.

Design and construction

After settling on the outer dimensions I started to search for inspiration for the internal structure of the vacuum tube. I wanted it to look a bit more realistic than the ones I saw at the stage and another project I found online.

The outer structure of the tube is inspired by an EL34 tube mainly because the glass bell has a rounded top like an EL34 without an exhaust tip at the top. The connection pins on an EL34 is connected to a brown or black socket part that would be a perfect way to connect the glass bell with the connection pins on my model. 

The internal structure is inspired by the front cover of a book from my collection called Build Your Own Audio Valve Amplifiers. I didn’t want it to look like the internal of an EL34 because there isn’t much to see other than a big solid metal plate. I found an EF89 in my parts bin that has a nicer metal grid around the heater and grid wires that can be seen beneath. The EF89 is commonly used as a R.F. Pentode in AM/FM radios. 

Starting from the inside and out the heater is built from two 230V LED filament light bulbs mounted top to top. Around the bulbs an enameled copper wire is wrapped imitating a grid. Around this grid another grid is wrapped around two threaded rods. The last layer is a thin perforated metal plate imitating the outer metal plate. The six threaded rods are held together in each end by the insulating spacers made from laser cut acrylic plates that are sanded to give them a matt finish like mica. At the top end two of the threaded rods are extended to work as mounting for the getter ring. At the bottom the internal structure of the vacuum tube is connected to the socket by thin copper tubes going from the threaded rods down to the pins in the socket. To straighten the copper tube before bending to the right angles I used my Tube Straightening Tool.
The socket is made by laser cut plates of plywood glued together to give the right height. The plates were made with holes for the eight pins which are glued on. The curved surface of the socket has been sanded down and plastered before a spray primer has been applied. The last step was to paint it with a black glossy spray paint to make the surface look piano black.
The two light bulbs are connected in parallel and the power cables to them are routed through two of the copper pipes and down through two individual pins and connected to a transparent copper wire. 

Final details

There are still room for minor upgrades:

• Make larger cutouts in the pins where the power cables go through them.
• The getter ring should be sanded and painted silver to look like metal.
• The top part of the glass bell should be painted dark silver to look like vaporized barium.
• As a lamp the amount of light from the two light bulbs is perfect, but as a model of a vacuum tube it would be nice to add a light dimmer to make the filament look a bit more realistic.

Parts list

1x Glass bell – glass envelope
9x 12mm round plywood plates – socket
8x metal tubes – pins
6x M6 metal threaded rods with nuts – internal structure
2x acrylic plates – insulating plates
1x acrylic circle – getter ring
2x LED filament light bulbs – filament
8x copper tubes – connection between pins and internal structure
1x Enameled copper wire – grid
1x Thin perforated metal plate – outer plate
1x 230V transparent copper wire 
8x Acrylic plate for connecting pins and copper tube
4x Acrylic plate for light bulbs
1x Acrylic socket top plate

Specification

Final thoughts

I think my giant vacuum tube lamp turned out almost as I had hoped for when I imagined it in my head. I spend the most time on completing the socket because I wasn’t happy with the result after the first time I painted it. The surface wasn’t smooth enough, so I had to sand down the paint and primer to make the surface more even before repaint. This had been a much easier task if I had had the right tools like a belt or disk sander to sand the wood in the first place. Much of the design has also been work in progress while building it since I did not made a complete 3D drawing of the vacuum tube prior to the build. That made it necessary to adjust and modify some parts throughout the build.
I think the final result looks much like a real vacuum tube (except for the bright heater) and I’m especially happy with how the connections from the pins to the internal structure has been made with thin copper tubes that looks realistic.

If you have any feedback please comment below or contact me. If you are interested in buying your own giant vacuum tube lamp please contact me and convince me to make another one for you.

Indlægget Giant Vacuum Tube Lamp blev først udgivet på Daths Garage.

What is it?

While searching around the web for nice electronics decorations and inspiration to The Circuit Board Coffee Table I found a nice digital clock built on a breadboard based around two different types of integrated circuits: the 4026 decade counter and the 4060 14-stage counter/divider. I’m fascinated by nice looking breadboard projects so I thought I could build it so it would look a little more sleek. This digital clock reminds me about the TTLCLOCK even though that contains a few more components. Another digital clock from KABtronics that contains many components is their Transistor Clock which is truly a nerdy wall decoration.

Before I learned about programming and microcontrollers I always kept away from electronics project involving anything that needed programming like microcontrollers, microprocessors or EEPROMs. I wasn’t sure where to start to get to learn about it, and I couldn’t imagine how they worked. Instead I would have loved to sit down and understand the schematic and build this digital clock when I was younger, since it is purely logic circuits and even some diode-resistor logic.

How does it work?

The nice thing about this breadboard digital clock is that it is rather easy to understand how it works, because it is divided into different modules.
The first part is the 4060 14-stage counter/divider connected to a 32768 oscillator, which gives a frequency of 32768 Hz/2^14 = 2 Hz. Two buttons Minutes and Hours are used to set the clock by increasing the frequency so the clock counts faster. The 2 Hz signal is input to the first 4026 that works as a divide by 2 and outputs a 1 Hz signal. The 4026 are designed to directly drive a 7-segment LED display rather than outputting a BCD signal that needs a BCD to 7-segment converter, this helps to reduce the component count. The two LEDs are also connected to the 1 Hz signal to indicate the seconds.
The counters for ones of seconds (red wires) and ones of minutes (grey wires) counts from 0-9. However the counters for tens of seconds (yellow wires) and tens of minutes (green wires) only counts from 0-5, and needs to reset afterwards. This is done by the resistor and the three diodes that works as a three input AND gate, when segments E,F,G are turned on (this combination is first met when count equals 6) the counter is reset. The ones of hours (brown wires) also counts from 0-9 but the tens of hours (blue wires) only counts from 0-2. These two counters must be reset when the combined counter equals 24. This is again done by the three diodes but now connected to a combination that first happens when the counter reaches 24 and now both counters are reset.
No resistors are needed between the 4026’s outputs and the 7-segment displays because the outputs only supplies around 1-3 mA. Since the LEDs in the 7-segment displays can not handle a 5 V supply voltage the two diodes 1N4007 are needed to give a voltage drop.

Why did I build it

Why would anyone bother to build something like a digital clock on a breadboard and waste a couple of hours on it? First of all I think it is fun to build stuff on breadboards even though they can be buggy, have bad wire connections and works bad at high frequency. Despite of all the wires and connections the clock actually worked the first time I powered it up. I know breadboard computers like the one from Ben Eaten is much more cool to look at and play with, but I like the simplicity of this design and its also a little more self contained – just connect power and it works. Playing around with breadboards is also a good way to learn about electronics because it can be more intuitive compared to multilayers PCBs with SMD components.
Another reason for building this digital clock is that I have a tradition every year with some old classmates to gather for Christmas lunch. Then we each have to brings some small presents for a Danish tradition called Christmas package game. Some should be repeats from last year and some should be homemade – this will be this year’s contribution.

Want your own?

If anyone is interested in building this digital clock on their own, the parts are listed in the link at the beginning. If you prefer to buy everything as a kit I might be considering to offer it with every component needed or in a fully assembled and tested version. Please contact my for inquiries.

Video

Link to the schematic

Indlægget Breadboard Integrated Circuit Digital Clock blev først udgivet på Daths Garage.