Information Processing @electricsteam - Tumblr Blog

(via https://www.youtube.com/watch?v=z_FehN93OeE)

Final Selector installed in the Silk Mill on a smart plinth and a retro acrylic table for the rotary dial telephone!

Final Selection!

The Strowger switch has been wired to activate one of three devices by dialling a two digit telephone number - 77 activates a motor, 39 a light bulb and 42 a brainbox sound module.

Upto 100 different devices could be connected to the Strowger unit each with its own unique number.

The Strowger switch has been slightly modified (yellow bridge wire on left of unit) so that the wires from each pair of upper and lower contacts at the back of the selector act as a make-switch. This enables any low voltage device to be activated by the unit - a radio, an alarm, an electronic circuit, a fan and so on..

“Final Selector”

On Wednesday the 8th of April, Daniel and I once again explored the Silk Mill stores - Daniel knew where we might find a dial telephone and I was on the hunt for the “Final Selector”!

We found both and yesterday afternoon and today I spent some time bringing the Final Selector back to life, much like the previous Group Selector, the device had not been in operation for some time and required generous amounts of penetrating oil to free the clogged mechanics.

After some fiddling with the wiring of the telephone and power connections, the Final Selector finally came to life! As you can see from the video below, the device responds to two dialled numbers and resets when the telephone cradle is depressed.

This sequential logic is all achieved through the bank of electromagnetic relays at the top of the device, with a complex maze of wiring at the back of the unit:

The next task will be to wire up a range of devices to the back of the switching mechanism where there are 4 banks each of 100 contacts (10 vertical, 10 horizontal):

By dialling a number, a light, a motor, a sound effect device can then be activated, upto 100 electrical objects can be controlled, each having an “address” between 00 and 99..

"Evo□tech" - a prototype card game on the evolution of technology

A laminated set of cards showing the evolution of technology. Each card has an image on the front and the date and information on the back.

Games might be guess the age, what is it, or competitive games winning the whole set by trumping the others players cards with either the more modern or the older technolgy.

Additional information might include size, weight, speed, memory, price, energy consumption.

The set could be extended to include many more cards covering different genres of technology - games, consoles, desktops, mainframes, mobiles.

Dialling a Strowger

For some time I have been planning on making an old rotary dial telephone control the Strowger switch, as this is what they are designed to do!

A telephone exchange consists of banks of Strowger switches able to route telephone calls from a dialled number. Dialling a three number code between 000 and 999 would support 1000 telephones, each with their own three digit number.

After some research digging around in the archives of the internet I discovered the wiring secrets behind the Strowger switch that would enable it to respond to a dialled number.

The back of the Strowger has 16 pin connector plug which locates onto a socket in the rack of the exchange. I needed to determine which of the 16 connectors at the back were for power, and what the rest were for. I took pictures of the back of the surplus Strowgers in the stores, hoping to decipher the key to the coloured wiring but could not find any information on what the colours meant.

Finally after browsing through hundreds of images of Strowger switches, I found labelled pictures of the connector plug on a blog with the catchy title “Final Selector”!

The picture shows how to connector power, each pin has two contact sides and the cardboard is used so power only goes to one side. All the pins were described and also a simple method of connecting a phone via the inbuilt test socket:

I connected the power and the phone, then dialled, but the switch only responded to the first number and not to two numbers as described on the blog.

After further research and much technical reading I discovered that there are two types of Strowger switches, Group Selectors and Final Selectors. The one I had found in the stores was a Group Selector and works differently from the Final Selector. For a three digit number the first number activates a Group Selector and the second two numbers control a Final Selector. Group Selectors are used to find a free Strowger unit that is not being used to handle another call, it does this by scanning through the connected units until one is located that is free, in this case it would be a Final Selector which then deals with the second two numbers. As the unit I had found was a Group Selector I wanted it to also try and scan looking for a free second Strowger switch.

More research led to the discovery of an essential control mechanism in the exchange, the “p-wire”. The p (private) wire enables Strowger switches to signal when they are being used and when they are free. On another website I found a method for fooling the Strowger switch that all its connected units were busy, which meant it would scan, searching for a free Strowger unit and not find one.

The video shows how fast the unit scans round after receiving the first number, as no free unit is found it goes back into its reset start position. The speed and noise it makes are quite impressive!

My next challenge is to try and locate a Final Selector and perhaps connect a few old phones to it so people might ring each other in the museum or instead connect other devices - lights, sound machines which would then be activated by a dialled number from the phone... One Final Selector on its own would enable a maximum of 100 phones to be connected. Or one of a 100 different devices could be activated by dialling a two digit number - 42, 21, 99, 77,12, 00.. By dialling a number, a recording might be made and played back, artefacts in the museum might come to life, or numbered light bulbs illuminate on a map or a poster..

electricsteam

Strowger Artifact Strowger switch controlled by two buttons, up and rotate. Finding and activating number 42 rings a bell.

Other numbers might activate different objects, lights, fans, sounds.. One Strowger Switch can respond to a number between 00 and 99, a 100 different things can be addressed, selected and activated.

Originally the pulsing would be controlled by a rotary dial on a telephone, but to make this work I would need to aquire an old phone and fix the connections between the relays at the top and the two power relays which step and rotate the lower selector switch. (To be investigated).

Beyond Information

My original ambition for the residency was to make an impact in the museum through the creation of an installation that would convey the rapid evolution of technology.

It was to be a hybrid of sculpture and projection combined with historical artefacts from the collection and elsewhere - for example my collection of mobile phones (1999-2015):

However an installation project is far too ambitious and is somewhat out of scope for the residency, where we are to provide a “kit of parts” that will enable visitors to do or make something, either self-led or guided by someone in the museum.

The challenge then is how to engage children with the ideas, facts and history of the recent technological evolution without the benefits of hands-on real physical artefacts or multimedia projection.

In my last workshop I learnt that plain sheets of information are not nearly as engaging in comparison to playing with an enticing kit of electronic parts - no real surprise there!

How might I make the history of technology accessible, engaging, bite sized and deliverable in the form of a kit of parts?

Can the information be transformed into a playful and engaging game that adults and children might play together?

Idea: A set of pictorial cards with images of technology on the front and historical and technical information on the back. The object of the game is to lay them down in order of time, from the most modern to the oldest.

There might be a range of games, guess the date of the mobile phone, which is the most powerful computer, which computer game came first?

Mock up of 12 cards (front faces)

Challenges: arrange in order of date, earliest first, or name the date?!

#electric

Guided Workshop Trial

On Saturday 7th March, rather than the previous open workshop where anyone could take a kit and build anything, I decided to trial a workshop with a set of instructions to produce a guided activity. The activity was designed to introduce the basic concepts of electricity before progressing on to building electronic circuits.

Rather than having a range of kits available, I chose to use only two, the Cambridge BrainBox Explorer and the John Adams HotWires kits. This meant I could easily manage two groups at a time, though this approach did result in a bit of a queue!

I showed parents and the children the information sheets, talking through the concepts and asking questions along the way

Sheet 1: What is electricity?

I discovered many of the children already knew about static electricity and had carried out the balloon experiment before. However they did not appear to know the origins of the term electricity.

Sheet 2 - Electricity behaves like water with a pressure (Voltage) and a current (flow):

This diagrammatic analogy appeared difficult to communicate successfully, producing some confusion and a subsequent lack of engagement. An actual water bottle might engage better, though the analogy is perhaps still going to be a bit opaque and is maybe better suited to older children learning about current and voltage.

Sheet 3: Batteries

The history of a battery and where the term Volt comes from did not appear to be that interesting as at this point I felt that children were simply desperately itching to just build something! Most children had already come across batteries being built from lemons (and potatoes).

Sheet 4: Conductance, resistance and capacitance.

At last, building a circuit using the kits!

Building the first circuit, "Conductors and Insulators" proved popular with parents joining in with things to test for conductance (car keys, phones, coins). It was a fun game for the children, would a piece of wood conduct electricity, a piece of paper, a balloon?

The second circuit "Resistance" highlighted the different approaches of the two kits, the Brainbox kit being a little more conceptual with the flow of electricity being shown using a meter, whilst the HotWires kit used an LED light in a dimmer circuit, which being more visual was perhaps a little more engaging and accessible.

Sheet 5: Capacitors

This proved conceptually difficult and problematic in understanding the functionality of the circuit. Once the operation of the HotWires circuit was understood, the use of two LED's successfully demonstrated the principle of a capacitor being charged and discharged. The BrainBox circuit again used a meter to illustrate a capacitor charging and discharging, however I did not feel this communicated the principles as successfully as the HotWires kit, perhaps lacking the strong visual impact of an LED light lighting up and fading out.

Sheet 6: Moving Electricity

At this point due to queues and possibly "too much information" only a few children built the sound circuit. Those that did enjoyed the noises, but I was not convinced that concepts on frequency and alternating current were really understood or perhaps were of any interest.

Conclusions

I learnt quite a lot from this exercise:

1. When presented with a kit of interesting looking parts in front of them, children simply wanted to get stuck in, rather than having to listen to someone trying to impart facts about electricity!

2. I underestimated the knowledge of the children; almost all of the children knew about static electricity and some had already created batteries out of lemons or potatoes at school.

3. The making of the circuits helped the concepts come alive. The conductance and insulator experiments proved fun and engaging as did the resistor circuit. The capacitor circuit and its underlying concepts however appeared a little difficult to both convey and grasp.

4. A balance has to be found between the time spent carrying out a making activity and the conveying of facts and underlying concepts.

Overall I felt the guided workshop was successful and that children did learn something, rather than simply constructing circuits with no real understanding of what they did, as in the first workshop. On reflection I feel that the guided workshop needs to be made shorter with less information and more making.

During the workshop the Strowger demonstration was also active and proved very popular with adults and children, both enjoying the challenge of finding the hidden number that would ring the bell.

My next challenge is to make connections between the old Strowger switch and modern technology. To achieved this I am planning on developing a set of of informative images as a means of conveying the rapid evolution of technology over the last seventy years. This may be presented digitally using a large screen or perhaps printed as a series of cards.

#electric

Open Workshop Trials

On Saturday 21st February I trialled four of the electronic kits (Brainbox Primary and Explorer, Hotwires and Matronix 130 in 1) to the public in the form of an open workshop where parents and children could drop by and build circuits. It was a great success and I was overwhelmed with enthusiastic participants, non-stop from 10.30 until 4.30!

Children of all ages, girls and boys built a variety of circuits with help from their parents, noisy sirens and music machines, touch activated noise generators, simple light and LED circuits, sound activated circuits, a voice recorder, light sensors, a circuit that changed pitch when you held two wires, a flying propeller (very popular), a radio and a morse code oscillator.

The kits proved very popular with many parents asking where they could be bought - suggesting that perhaps the kits might be something the museum could stock and sell in the future.

Much was learnt from the exercise, and the kits were severely tested both physically and electrically. Supervision is important as some children quite liked to assemble their own made up circuits, which could either blow a fuse (there are safety fuses on the batteries) or possible damage a sensitive component (a transistor or Integrated Circuit).

Although the open workshop was popular and everyone enjoyed themselves building working circuits, in retrospect I felt that a structure is necessary to encourage learning of the basics of electronics and to communicate essential concepts such as what is a circuit, how does electricity flow, what conducts electricity and so on. It is very easy to assemble a working circuit but not learn anything in the process even though the completed circuit may be rewarding and enticing giving off noise and light.

A kit of parts for the museum would therefore consist of instructions on building a set of specific circuits rather than the full range of over 100 different possibilities. The choice of circuits would be designed to be presented in a series of stages, taking the participants from the basics through to the more complex concepts of resistors, capacitors, diodes and transistors. Once the fundamentals are grasped then the option to build any circuit might then be given.

Comparative review

The instructions presented with the kits varied in information content, only the more complex Matronix 130 in1 included 'real' circuit diagrams, though this kit was not as popular with the younger children being too complex to understand and assemble. To be fair, due to the design of the components, the visual representation of both Hotwires and Brainbox kits are essentially circuit diagrams, so perhaps a black and white electronic circuit digram would be superfluous as the illustration of a Brainbox Explorer circuit below demonstrates:

Both the Brainbox Explorer and the Hotwires kit share a similar approach in the creation of easy to assemble "pop-stud" circuits and include nearly identical parts - a motor and flying spinner, two battery units, five "black box modules" (radio, 3 sound generators, sound recorder, amplifier). In my opinion I felt that the Brainbox Explorer perhaps has the edge over the Hotwires kit (and is somewhat more expensive), offering more circuits and including more parts such as a reed switch and magnet, a thyristor, an eight segment LED display, a meter for measuring current and voltage and a solar panel which could be used to introduce ideas on "green energy". The flying spinner in the Brainbox kit is also of a lot sturdier construction than that supplied in the Hotwires kit.

That said, the Hotwires manual I felt was much clearer and more visually appealing than the Brainbox manual. I also found that some of the Brainbox Explorer illustrations were far too small (making part numbers difficult to read) in comparison with the brighter and more legible design of the manual in the Hotwires kit.

Brainbox light sensing circuit:

Hotwires light sensing circuit:

The Brainbox Explorer professes to offers over 900 circuits to build, though to be honest I would suggest the number is more like 200 circuits with small variations in creating different sound effects or changing the input and output devices. In comparison Hotwires advertises as offering 100 circuits to build (112 in the manual), though I would estimate there are actually around 60 different circuits with the additional 40 plus again being produced through variations in sound effects, sensors and outputs.

#electric

Electrical Kits!

The Brainbox Primary 2 kit arrived on Friday.

The AND and OR gate:

Circuits are very easy to assemble - parts "pop" together via press studs and the physical form of the assembly represents the electrical circuit diagram.

I changed the OR and the AND to work with an LED rather than a bulb:

Logical AND circuit:

Both switches have to be on together (A AND B) to complete the circuit and power the LED light.

Logical OR circuit : Either switch will complete the circuit (A OR B) and power the LED light.

Other circuits utilise a rather loud sound module:

There are no transistors in this Kit which is a pity and the next kit up, the Primary Plus 2 includes additional "black box" modules rather than electronic parts such as transistors, resistors and capacitors. I would prefer circuits that demonstrate basic electronic principles - eg the switching of a transistor rather than provide ready to go modules which do not convey anything about how they operate or are built. The more advanced kits such as the Brainbox Explorer does include transistors and other components enabling these basics to be covered and more complex circuits to be built.

The John Adams Hot Wires kit utilities the same pop stud assembly method as Brainbox and their kit does include transistors, resistors, capacitors and ready-to-go amplifier, recorder and sound modules. I have ordered one of these to test, compare and contrast with Brainbox.

HotWires circuit board:

Matronix 130 in 1 Electronics Lab

An alternative approach to creating circuits is using springs as connection posts as in the early Phillips EE kit I mentioned in the previous post. The Matronix in the 130 in 1 Electronics Lab utilses this method, but instead of having loose components (that can easily get lost) all the components are mounted on a console. At the weekend, I just happened to find one in a local charity shop:

There are many components available here, 12 resistors, 12 capacitors, three transistors, three LEDS, an eight segment digital display and two op amps and a number of NAND gates. The manual lists 130 different circuits, some of which are quite complex and in-depth as well as more basic circuits.

LED "strobe circuit" with added speaker output:

One of the problems with this approach, though offering a great range of circuits is the disparity between the visual form of the final circuit and the circuit diagram, something preserved in the press-stud approach adopted by the BrainBox and John Adams kits. The circuits can quickly resemble a birds nest of wires, and it is a cognitive task to trace a circuit and ensure it is wired up correctly.

"Synthetic cat" circuit:

The circuit diagram above is actually very clear and simple yet translates to a complexity of wires in the kit. However, the number of circuits that can be created are plentiful, fun and educational.

#electric

Making Workshops

The Strowger switch is an interesting archaic electromagnetic switching artifact, dating back from the first automated telephone exchanges. It will act as an interesting conversational point and source of information on early information processing. How might the public further engage with ideas on computing, logic, sensing, effecting and information processing through a making workshop ?

In my youth I learnt basic electronics and computers from constructing with an educational kit then later building my own circuits and devices. I thought the Philips EE - Electronic Engineer kit was brilliant!

There were a range of circuits to build, each on a printed sheet you fixed to the workboard then fixed springs onto the connector points followed by inserting all the right components into the spring units. You could make radios, flashing lights, an intercom, amplifiers, a mini organ and burglar, light and moisture alarms!

I have examined a range of modern day kits looking for simplicity, robustness and clear communication of educational aspects and have found a range of kits that could provide a basis for a making workshop.

Rather than a workshop creating a range of electronic possibilities, the idea would be to focus on a small selection that would embody some of the essential ideas behind information processing of logic, sensing and effecting.

The kits below do not require lots of wire to assemble, they are all plug and play and identify the components using electronic symbols, though there also some black box units which are likely to contain an integrated circuit dedicated to providing a specific function - eg amplify, make sound.

Logiblocs

Cambridge BrainBox

John Adams HotWires

Over the next week or so I will be examining and playing with a number of these kits, with the view to testing out ideas using them in a public arena at the Silk Mill.

#electric

Strowger Artifact Strowger switch controlled by two buttons, up and rotate. Finding and activating number 42 rings a bell.

Other numbers might activate different objects, lights, fans, sounds.. One Strowger Switch can respond to a number between 00 and 99, a 100 different things can be addressed, selected and activated.

#electric

Strowger Switch

Today with help from Steam Mill curator Daniel, I borrowed a few items from a box of spare parts in the collections store (a wondrous Aladdin’s cave), a Strowger switch assembly and an old telephone. I had brought along two 20v DC power supplies to see if I might with the help of electricity bring the switch to life!

The first thing was to locate the two electromagnetic units that stepped the switch up/down and rotationally, this done then to apply power - as I expected 20v was not enough as the old phone systems ran on 48V. However wiring the two power supplies in series produced a healthy 40V which was enough to activate the mechanism. After possibly 50 years of slumber and a few squirts of WD40, the switch noisily came to exciting life!!

The noise at the end is when the unit mechanically resets at the end of a rotational sequence of 10 steps.

Close up of control logic relays at the top of unit:

Close up of Strowger switching assembly, showing 3 x 10 banks, each with 10 contacts. The central arm can step up to one of the 10 banks then rotate round to access 1 of the 10 contacts as the electromagnets are activated.

This is the principle behind the first automated telephone exchanges, instead of an operator plugging in a patch to a telephone number, the unit steps through sequences according to the number dialled from a telephone dial, with one Strowger switch this would support 99 numbers, for example dialling 42 would move the switch up to bank 4 then round to contact 2.

As an experiment I attempted to wire in an old phone to drive the Strowger switch..

Inside the phone after taking base cover off:

Circuit diagram on back of base cover:

So I naively wired one of the Strowger stepping coils directly to connections 1 and 9, but on dialling with the old phone the Strowger mechanism could not keep up, and after further research it appears I need to utilise some of the relays on the top part of the unit:

According to the technical information here, this is what the circuit above actually does: "Although one would never connect a dial directly to a connector, the diagram above (from the 1950's guide "Electrical Principles of Telephony", Bulletin 800, produced by Automatic Electric, a subsidiary of General Telephone and Electronics) describes quite well how a Strowger switch operates. Upon lifting the receiver, the subscriber's telephone closes the line circuit and pulls the pulsing relay in. In turn, the holding relay and the sequence relays also operate. Let us now assume the caller dials "3-4". The first number, 3, generates three quick pulses on the pulsing relay (a fast-acting relay). Although this breaks the circuit to the holding relay, that relay has a copper sleeve on the heel which causes it to hold down for about one-third of a second so during the pulse train it stays pulled-in. Each time the pulsing relay operates pulses are sent through the holding and sequence relay contacts to the vertical magnets causing the strowger switch to step upwards three pulses to the third bank-contact level. "

So the next challenge might be to enable someone to activate the unit by dialling on an old phone, or is it more fun to press a button to step the unit up and press another button to step it round? Could someone work out how to activate an imaginary phone connected to say number "42"?

#electric

STEAM Residency - inspirations

Old Strowger Switch assembly - based on the first electrically operated automatic telephone exchange invented by an undertaker in 1888, see wikipedia entry for more info!

Another hidden gem in the Silk Mill collection, a PDP8e!! So this might not mean much to most folk, but this, like the relays in the Strowger switch brings back fond memories. I was a geeky child and built an 8 bit memory computer out of old GPO relays when I was 12. At uni I wrote a Turing machine simulation on a PDP 11. The aesthetics of this piece of tech are simply sublime, the colours, the styling the design - and just look at those switches, simply calling to be pressed!

“The 12-bit PDP-8 was the first successful commercial minicomputer produced by Digital Equipment Corporation (DEC) in the 1960s. DEC introduced it on 22 March 1965, and sold more than 50,000 systems, the most of any computer up to that date.” Wikipedia

I also have a BBC micro, bought in the 80's, these early 8 bit machines along with the Sinclair Spectrum, the Commodore 64 and the later Amiga range (with Midi!) represented the early stages of the popularisation of the home computer.

Now our mobile phones are in fact mobile computers far smaller and far far more powerful than any of the above. Its a digital evolution, they are getting smaller and more powerful and more ubiquitous, they are everywhere.

So how can all this be used in STEAM? Time for a mind map:

And if I reduce this down to something a little more coherent:

A sculptural installation, a conical banner of images, a projection combining real objects to convey the sense of increasing power and things getting smaller to the point they disappear in 2050, the nano or the quantum computer.

What is common in all these machines is that they are about Electrical Information Processing, they use logic, electrical machines to process data.

On one side information goes in, it is processed and comes out the other side as useful data. Way before the digital this used to be carried out mechanically, with cogs and levers and just before the digital it was carried out using analogue components.

There are many famous names associated with the history and invention of computing - Ada Lovelace who in 1842 invented the concept of programming and who's father was the infamous Lord Byron, Ada worked with Charles Babbage credited as the inventor of the first mechanical computer (The Difference Engine) it was never built, though the Science Museum has reconstructed one based on Babbage's drawings:

AlanTuring (1912-1954) created mathematical and conceptual ideas about what is possible to compute. Then there are all the people who invented all the bits that make the modern computer, from valves, through to transistors and integrated circuits. It is a rich and complex history, almost invisible and unknown, yet rapidly advancing - the first electronic computer ENIAC (Electronic Numerical Integrator And Computer) was a huge contraption weighing over 27 tons and occupied a very large room, it was invented in 1946, only 69 years ago!

(The control panel of ENIAC)

All well and good. But how might people engage with computing and information processing, how might they learn a little about what goes on inside their portable super computer touchy feely swipey aluminium plastic and glass blocks (mobiles)?

One of the basic principles in digital computing is logic, ons and offs, that can represent real world states. If A AND B are true then do something, A might be "I am hungry" B might be " I have £5" and other might be C "the cafe is open", if all of these are true I can go and eat something.

This simple logic gate can be represented by three switches, all of which have to be on before the output - "go and eat" is true. Logic can also be realised using relays, transistors or integrated circuits.

There are other logic functions, OR, EXOR and NOT, combine millions of these together, put them in chips, shrink them down and there you have it a computer. Ok its not quite that simple, but that is the principle. One also needs memory, chips that store information, and this is the key to programming and software..

The ideas of Logic and Information Processing will be used alongside the concept of interfaces (sensors and effectors) between the machine and us as the basis for a series of workshops designed to reveal a little of what we so take for granted....the hidden dark arts behind the computer and the mobile phone...

#electric

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