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.

Disclaimer: This review is not sponsored or paid by the supplier or anyone else. The product is payed by myself and I wanted to share my personal experience with you.

The problem

I’m not really a fan of specialized tools that can only be used for one single purpose and solves one specific problem. Neither in the household nor in my workshop. Nevertheless I found myself in need of buying a tool for solving a very specific problem. For different future ideas and projects like my Giant Vacuum Tube Model and a LED chandelier. I have been looking at using 4 mm copper tubing. The only problem is that it’s almost only sold in rolls that need to be straightened before it can be used – Unless you want to buy overpriced pieces of 1 m sections. First I didn’t know the name of a tool for solving this task, but found out it is called a handheld tube straightening tool or tube straightener. By searching around for ways to straighten copper tubes I came across many not very useful tips and tools. One YouTube video suggested to fix the tube in a clamp and then use a hammer to stretch it straight by hammering. 
The first dedicated tool I found was a pair of pliers that just clamped around a 5-10 cm piece of the tube and then had to be repeated for the total length of the tube. Unfortunately the end result was not looking very convincing and my guess is that it would be a very time consuming job. Another way to straighten a tube, either large or small diameter is to force it through several ball bearings with a fitting for the specific tube diameter. This principle is often used when the tube is fed directly into a tube cutting or bending machine often with a dual tube straightening mechanism, one in the horizontal axis and one turned 90 degrees to the vertical axis. Another more compact version of this mechanism is to mount the horizontal and vertical parts together forming a cross like structure around the tube. 

The only tool for the Job

Only one product repeated to show up through my searching; the Tube Straightening Tool from Kwix UK. After not being able to find a Danish distributor and with the, in my opinion, relatively high price I thought it would be rather simple just to 3d print the four pieces that holds the ball bearings together with the screws. First I tried to build a simple mock up with 6 cheap ball bearings mounted on a plate, but it couldn’t take the force from the straightening process and after a short testing the ball bearings all broke apart. After my first very bad prototype I quickly abandoned the idea of doing it myself and threw my money after the real product instead of wasting my time and money on the design process and materials. My hypnosis was that if a company can exist by producing one single product its better be good. And hopefully the price would reflect the quality of the product.  Sometimes you need to focus on what you want to use your energy on, for me it wasn’t to design the deep plate over again. 

The strange thing was that I wasn’t able to find any similar products for straightening a copper tube in my regular goto hardware stores. Not even though some of them actually sold copper tubes rolled on a spool. 
Another challenge is to cut the copper tube in the right length or bend it at a specific angle, but this is not a problem since a tube cutter or tube bender are tools that can easily be found around in hardware stores. 

A short introduction video from Kwix UK

My experience

Now lets get to the actual review of this product. My experience with this product is that it does a good job on 4 mm copper tubes. I haven’t tried with other materials, and only used the 4 mm version. The end result varies depending on if the tube comes fresh from the spool or if it has been slightly bend by hand in different directions. Then it is harder to get a good end result with a complete straight tube without small curves. But in my opinion this product does a pretty descent job. And it definitely feels sturdy and strong enough to withstand the force of the straightening process. THe hardest part is to get started on the tube, it helps to hand straight the first 10 cm. Then it is easier to get in inside between the wheels.
My only regret about the product is that I don’t feel like working with tubes in other diameters than 4 mm since I don’t want to invest in multiple tools to be able to handle different tube diameters. But for the professional user I definitely think it is worth it’s price even if you have to buy multiple sizes. I look forward to be using my tube straightener more for future projects.

Indlægget Review: Kwix UK 4 mm Tube Straightening Tool blev først udgivet på Daths Garage.

Background

The first microcontroller I learned to program and got to understand the architecture of was the Atmel ATmega16/32 in a DIP40 package programmed with a STK500 board that can also be found on The Circuit Board Coffee Table. This chip fascinated me with all it’s build in peripherals inside a single chip. Other chips that I later played around with were the Microchip 16F877 and 18F4550 with USB interface. When I got interested in retro computing I came to know about 6809, 6502, Z80 and 8088/86, which all shared the common DIP40 package. I found myself collecting these devices without really knowing why and not knowing how to display them. I just knew I didn’t want to start a huge CPU collection, so I limited myself to the DIP40 form factor. Then at a natural museum’s shop I saw this little showcase with butterflies, wondering how cool it would look like with old DIP40 ICs in it instead of animals. I found the perfect frame for the showcase with an IKEA HOVSTA frame that had the right depth.

The ICs would be mounted in precision machined IC sockets soldered onto prototyping PCBs so it would be possible to swap them around if some was added or removed from the collection. 

Scope of the collection

The overall theme of the DIP40 Frame of Fame is famous DIP40 microcontrollers and microprocessors with a few exceptions by type and package. Since the DIP40 package is now almost obsolete with new microcontrollers, breadboard friendly microcontrollers, mounted on a DIP40 size breakout board, are also included in the collection. This is my little version of a CPU collection with items I think has an importance to computer history. The name DIP40 Frame of Fame is somehow self explaining but is inspired from the Chip Hall of Fame.

Below is a list of the 21 ICs that can be seen in the DIP40 Frame of Fame sorted by release date and with a short description of specifications and a justification for relevance.

Specifications

Disclaimer: The above information and years are based on Wikipedia articles and datasheets and are my best guesses. If you have any corrections you are welcome to contact me.

Indlægget DIP40 Frame of Fame blev først udgivet på Daths Garage.

It all started with an old factory that was about to be cleared of inventory before demolition. I was allowed to get a lot of old SAIA PCA1 PLC systems for free I just had to remove them myself. Unfortunately I don’t have any pictures from the PLC room. But imaging a room the size of a small office packed with PLC racks along all the walls of the room. Unfortunately the room had been vandalized so the cabinet doors had been broken open and some of the equipment had been smashed.

However I managed to salvage around 20 complete PLC systems from the room together with several hundreds of SPDT relays mounted in the racks and connected to the outputs of the PLCs. The relays are still lying around somewhere in a box waiting for me to build something cool out of them like playing with Digital Relay logic, build a Digital Relay Clock, or something like a Single Board Relay Computer. However my main reason for keeping them is to build a relay version of the discrete logic in the SN74LS181 4-bit ALU.

In each PLC unit there was a motherboard consisting of an Intel 8085 8-bit microprocessor together with 62256 RAM, 8255 PPI, 8251 UART and 8253 Timer chips and the corresponding control logic. On two modules on top of the motherboard up to eight I/O boards were connected. As I understand it, these boards were ADC input board, multiplexer boards for BCD switches, output TRIAC boards, mixed input output boards, communication modules to passive extension housing modules without the CPU but with room for eight extra I/O boards. 

For a long time I didn’t know what to use all that equipment for, clearly it didn’t work. Most of the motherboards had clear signs of leaking backup batteries and some was missing the program EEPROMs. I kept them because I wanted to build a nice visual decoration out of it.

One night I was searching around on Google image search about circuit board decoration and came across Chris Harrison’s Circuit Table. Immediately I knew what to do with my pile of old circuit boards and computer motherboards, I wanted to build something like Chris’s table. Instead of the IKEA Lack table that he used as a basis I wanted to go with a bit more industrial look. I started to make a drawing in Sketchup with one of my favorite building materials 20×20 extruded aluminum profiles.

The final design ended up much like I had imagined with a nice industrial look. The PCBs should be mounted under the top glass plate on a wooden plate. The lower horizontal part of the chassis stabilizes the legs and makes it possible to install a second wooden plate as a shelve by adding some extra support beams.

Parts needed for the table:

• glass plate 10mm, 135×75 cm
• wooden plywood plate(s) 12mm, 120×60 cm
• 8x 200cm 20×20 extruded aluminum profiles
• Screws and assembly corners for the beams

After a quick search for the parts needed for the table and prices, I realized that it would cost way more than what I was willing to spend on it. Especially because there isn’t room for the coffee table in my workshop at the moment. Instead of buying the glass plate new from a glazier I thought about reusing it from a second hand coffee table found online. Luckily I found a table with a glass plate of the correct dimensions on DBA in a nearby city. When I got the table home I realized that it would actually be possible to reuse the entire table with glass plate and metal chassis with minor changes.

On top of the grey metal legs the plywood plate is installed and then the round tubes holding the table is just mounted on top of the wooden plate. Everything is kept in place my a threaded rod inside the round tubes. The plywood plate was prepared by cutting it to the right size, drilling holes in each corner for the threaded rod, sand it down and painting.

After this the fun part begun; playing PCB Tetris, by installing them on the wooden plate and make them fit with the least overhang and avoid empty holes in between. The available Tetris pieces was the PCBs from the PLC (the reason why I got the idea to this project), some old PC motherboards with RAM and CPU and graphic cards I had harvested from computers found lying around for bulky waste and old development boards. After playing around with different layouts I found a solution were everything fit optimal.
Instead of just being a static decoration without anything happening, I wanted the table to have some dynamic features that could be implemented sometime in the future like a spinning fan, clicking relays or blinking LEDs. That is the reason for installing the LED diagnostics panel from an old IBM server acting as a Blinkenlights. There were also room for a small LED dot matrix scrolling display. Everything should be controlled from a small ESP8266 controlled through WiFi.
At the moment only the LED matrix display is controlled through the ESP8266. The device connects to my local network through WiFi, and then the display starts to show it’s IP address. When going to this page a small web server is loaded where a message can be entered to display on the display.

A video showing the scrolling message, the table is shown without the glass plate mounted.

I’m very happy about the final design of the table, especially because I found a perfect donor table that saved me a lot of money since I didn’t had to buy the extruded aluminum profiles and the glass plate. This also greatly reduced the time I took for me to build the table.
After assembling this table I still had plenty old printed circuit boards left so I assembled another wooden plate with some of them. The purpose of this could be to make another table. If anyone is interested in buying one contact me? For now I will use the plate as a background frame when taking pictures of the different items for my retro computer collection

Indlægget The Circuit Board Coffee Table blev først udgivet på Daths Garage.