20220416

I finally assembled the Arradio revision I’ve been working on for a month. Its a great piece of gear and the revision adds a lot to the original. The reception using a SMA connector and telescope antenna is way better than with the RCA connector that the original used, the latch toggle works as expected and the tuning is very accurate. The module is skiff friendly and 4hp wide (2hp smaller then the original). I named the revision “Radio Kid” so that if the design has problems it will not be mixed with the original Arradio. I’ve had very positive exchange with the designer of the original and I hope they will approve of my revision.

It took while for the PCB to arrive and I had made mistakes which took some figuring out (pot-reversed, missing 100k transistor). I will rework the PCB design to fit some components better. The U.FL-R-SMT(10) connector is in the way of the RCA connector, which isn’t a problem if only the SMA/antenna is used but it is an easy fix. The panel holes need to be moved a millimetre to the left because the bottom-pcb solder-points are too close to the edge of the unit. The optional RCA connector space is too tight and I want to design a narrow (2hp) panel (also in 1u) which can be used as an alternative mount the antenna, so that it wont be in the way.

I’m really happy that the panel design works as well as it does. The SMA mount hole was made by milling a C shape that can be snapped off to fit the connector. I placed credits to Arradio (and Befaker) on PCB as silkscreen. For the next revision I will make silkscreen drawing of a kids hand toggling a radio tuner in the back of the PCBs. I credited the revision design to Ore.e Refineries.

20220315

– Well,  [David] Tudor was one of my first customers. [John] Cage and Tudor visited me at my studio in Berkeley and I remember that occasion. My studio at that time was ten feet wide and I worked out on the sidewalk. It was so crowded in there we hauled the workbench out on the sidewalk on good days and set up my oscilloscope and worked out there. Cage came by and for voltage control I had hooked up my keyboard to an FM module that I’d built, a little module that was an FM receiver and I could play stations on it because I had one of the first veractor tuned FMs. Cage, as you can imagine was, just enormously interested in the fact that I could tune each key to a station and then proceeded to play the radio. I had already met Cage while putting together some of his pieces that involved perhaps multiple radios, phonographs and so on. At that time, in fact the first instrument that he encountered that I had built was a device that gave you a pitch according to where you were along the sound beam. Add it was a guidance device for the blind. At that time I was working a lot with prosthetics for the blind and Cage played it as a musical instrument in this piece and then later on saw my voltage control tuner. He didn’t actually purchase one. I’m not sure that I was offering it for sale in fact. But David Tudor came along with him and commissioned a sound locator that was based on a very beautiful Aztec-looking design. Four circular motifs in which you played a five-channel sound system. Four speakers in the corners of the room and a fifth directly overhead. That was my way of making a equal interval polyhedron. Not taking care of the bottom but certainly the top and Cage bought that and the rather complex voltage controlled amplifier that it controlled to distribute sounds and he used in a number of pieces. I believed he used it in a early version of the Rain Forest Piece.

– Do you recall the date of that?
– I have a hard time with years to tell you the truth.

– The 60s of course?
– Oh early or mid sixties .

– What was the war doing?
– This was early 100 series stuff.  By ’69 I had abandoned the 100 series so it would be around ’66.

Extract from 1991 Buchla tape transcription from the Steina and Woody Vasulka archives.

I submitted a PCB design revision of the Arradio module to a factory. Made the design using KiCad and called the unit Radio Kid. The revision uses a different FM radio submodule, includes reverse voltage protection, the output has a 1k buffer, the board is fitted with a U.fl-smt-1(01) connector for a SMA antenna connector (optionally mounted on the panel), the circuit includes a “latch-toggle” which prevents the tda7088 locking to FM channels and it is 2hp smaller then the original. Small changes to the original design, yet milestone in for my electronics hobby.

20220214

Built an Arradio module over the weekend with a new friend I met trough muusikoiden.net/tori. I posted a prompt to borrow an Arradio module to study its circuitry which led to a process where we managed to source parts and pcbs to build a few units. To confirm my earlier notes, the tda7088 pin1 to 3,3v power line via 33k on a switch (currently 30k) does indeed work as a channel latch mechanism and toggling it changes the tuning behaviour. We changed the original design by adding polarity protection diodes 1N5817 (instead of the ferrites, but still including them) and I added a 1k resistor to the output (cut the trace on the pcb and soldered a 1k smd resistor as a bridge). Neither additions might not be necessary but I feel more confident exploring the circuit with these changes. I’ll proceed to test the unit with different radio sub-modules and possibly designing a new pcb layout. The current unit also has a I/O switch which I’ll need to study too… It cuts the power from the FM receiver sub-module and I’m not sure if it has (or needs) surge protection circuitry.

Updates:

Drilled a hole to the faceplate to accommodate a sub-mini switch hooked to toggle the latching mechanism. I tested if the circuit “Scan” feature could be activated with a button (3,3v to pin15) but this only produced glitches. I think the tuning potentiometer control voltage should be squeezed with a resistor for it to work (or even disengaged). The Conrad “UKW Retro Radio” schematics which the sub-module is based on show a 200k resistor between the tuning pot(s) and the RE2 trace which lead to the “Reset”/pin16 (perhaps serving as a voltage divider?). The “Reset” also works for manual tuning. The new “retro radio” board wiring examples show a 1m resistor after the tuning pot(s). I should test the minimum voltage the chip needs for manual tuning and add a voltage divider accordingly. The “Scan” is on pin15 and I think a constant voltage at at “Reset”/manual tuning prevents it from working. I’ll test having 0 voltage present at the RE2 trace will enable the “Scan”.

I don’t have any radio reception in the basement I work in, which defeats the purpose of having a radio. Spend a few days building antennas. I had most luck with a 2x 75cm dipole antenna made from insulated scrap copper but I’d have to set it up 10-15 meters out to our housing companies backyard, which might cause suspicions. Touching base with the radio-hobbyist scene.

20220130

Agroecology and the Survival of Cuban Socialism (2021) Aidan Ratchford offers a glimpse to how Cubas modern (monoculture) sugar farming industry was developed into a pluralistic farming praxis. Interesting to note that the development they underwent rid the country of the binary division between urban and rural.

The resilience of maintaining its socialist principles has been crucial to this experience of degrowth; only an economy which prohibits landlordism, structural inequality, and the accumulation of private wealth and means of production, can strive for genuine degrowth. In this sense degrowth as a real life experiment has necessarily a socialist character, given that the fundamental principles of capitalism are incompatible with the above. This is not to say that capitalism will not have its own “degrowth” given the threat of climate change but this “degrowth” will be the forced underconsumption of use values by the Global Poor, not Cuba’s sundering of social wealth (i.e. use values) from capitalist valuation.

Ethics & Epistemology (1998) a nice extract from a discussion exploring  the different understandings of freedom which Hegel, Engel and Marx deployed. Particularly how Engels statement “freedom is the recognition of necessity” can be understood. The analysis investigates how the thinkers approached nature and I like the definition that of our freedom can be measured by investigating how well we achieve in the projects we undertake: Ecological sustainability is freedom! The text explains that some mistakes of the Soviet Union where a result of a misfortunate process where the Second International chose to revive Hegel’s notion of freedom as an internal state which does not demand an engagement with the world. This enabled the state to limit individual freedom so that it could compete in overall productivity with capitalist societies, so that history would complete itself – Instead of deepening an investigation to what productivity, progress and history actually are.

For both Marx and Hegel human beings realise their essence through recognising themselves in the world beyond. For Hegel this takes place in the realm of the Mind, of thought, and is essentially an act of contemplation. For Marx however, it is through activity, through interaction with the external world outside themselves that human beings realise their own nature. This involves not only work, production, that is the moulding of nature to human design, but also social interaction where people recognise in each other their own selves.

The practice of the International was to submit to ‘historical necessity’ – ‘scientific’ laws that determined the movement of society – which would of their own accord pave the way for socialism. This was the opposite of Marx’s approach, who argued that the fact that social relations could be analysed scientifically, as governed by laws that acted independently of humanity, was itself precisely the state of affairs that needed to be overcome through socialist revolution.

Working towards an Arradio FM receiver module. Sourced schematics & the pcb layout and investigated the circuitry thoroughly. The Arradio hosts a sub-module from an FM radio kit which is no longer available but there seems to be an alternative to the sub-module Steckmodul mit TDA7088 which has the same components and the 70nH & 78nH inductors, which the tda7088 schematics call for are designed into the pcb. The varicap/capacitor diode 1SV101 which handles the voltage based tuning is a rare component but not completely lost yet. There is also an AM circuit which, if I understand it correctly can piggybacks on tda7088 tuning mechanism (or CD9088CB which is the same chip).

The previous schematic also shows a 33k resistors attached to the pin1 which is defined as a “mute” toggle on the chip datasheet (other sources I’ve spotted show a 10k resistor in the same arrangement). If I understand it correctly the “mute” can be understood as a channel latching mechanism, which enables the radio to lock to strong FM signals when the chips “scan” feature is used. A post by Lui Gough defines the mute as “a frequency locked loop with internal muting of weak signals”. Disabling this “tuning lock/mute” might enable a FM receiver unit build around the chip to linger in-between channels for unbeautiful static noises. I will investigate this further as I don’t actually know how the current circuitry behaves. This post offers a thorough breakdown of the chip. I know that the mute switch on the Arradio only cuts the device power input. If my experiments are successfully I will propose (Arradio developer) that that I’d update the design so that it would support the newer fm sub-module and that the submodule control & audio amplification circuit tl074 would be made using smd components.

I’d also like to change the pot and jack-in footprints to match more common components, include reverse voltage circuitry and possible switches for the “mute” and “scan” features (while reducing a hp or two).  Eventually I’d like to try building the submodule could be build straight to the pcb. Learning KiCad!

Sourced two 1SV101s and I’m hoping to test them with the mini-FM transmitter. No idea if it would work thou.

20210925

When sourcing parts for a RYO Paths module, I discovered that the Fairchild FJN3303R NPN Transistor is no longer manufactured. Searches on Octapart indicate that some companies still have the transistor in stock but they unfortunately only sell the chip in big batches. A company called Rochester Electronics would only sell me 12940 units and AVnet 16026. Both companies seem to supply electronic components for the manufacturing industry. If someone were to build over 5000 Paths this would make sense (the module requires three transistors). Modular grid indicates that around 700 users have the module already, so I imagine the market is saturated by now. The module seems to be from 2015 and there are dozens with similar functionality available. Perhaps 5000 sequential switches could be used to build a computer of sorts.

There are some potential substitutes for the transistor but I’m not skilled enough yet to confirm if the specs are a match. So I turned to ebay, aliexpress and other dodgy vendors. Some claim to be selling the same transistor but the price of a single unit is over 10€. It is also impossible to confirm that the chip is the right one.

Luckily the Modwiggler forum has a DIY Trade Thread [ Parts, PCBs, Panels ] where users announce stuff they are looking to trade with others. I found two entries both from 6-7 years ago from users indicating that they had some transistors to spare. I contacted one, got no reply, contacted the other and got a reply, and then the first contacted me too. Now I’m expecting to get 20 transistors in the mail! In a brief exchange we agreed that I’ll commit to distributing the extra units for builders/hobbyist from Helsinki. I got the units for free and I’m committed to distributing them further asking nothing in return.

It turns out electronics as a hobby is about supply chains, archivist practices and social commitment. Turns out hardware is about care. The module is interconnected by design and its manufacturing depends on the good will of other builders. For me the rarity of the transistor is now a facevalue of the module. It makes me a part of the Fairchild FJN3303R NPN supply chain, a member of the rare transistor-gild!

In the process I also learned of the phases of the ljunggrenaudio/RYO eurorack manufacturer. A few years back (between 2016-19) they gave up on business due to health concerns and disappeared.  As their website ljunggrenaudio.com went down and got squatted, the schematics, technical notes, build manuals and patch notes were lost. In recent years the hobbyist community and their past collaborators have sourced the lost documents. They are currently housed on modwiggler and other sites. With out the documentation servicing and building the modules would have been difficult.

The short online-amnesia caused by lost documentations, the rarity of the transistors and the fate of ljunggrenaudio/RYO make the module build process more then a mere assembly (which most DIY kits are). It feels almost like a media archaeological excavation. I would like to learn more about the transistor thou and other things it is used for. I’ll distribute the Fairchild chips I was handed via Ore.e Refineries. I’m amazed by the realization that electronic components, chips and the logics, behaviour and functionality they poses are so finite. Already noted this when I started electronics as a hobby and it feel great to return to this with the Ore.e Ref. Fairchild supply initiative.