The inner beauty of a Tesla Stropkov DS 3600 telephone from the early 1980s | Hacker News Reader

The inner beauty of a Tesla Stropkov DS 3600 telephone from the early 1980s

blog.jgc.org

114 pointsjgrahamc77 comments

On an analog phone line (two wires) the transmitted and received audio coexist. Obviously the transmitted audio is far, far louder than the received. The hybrid (the parts in the handset) subtracts most of the transmitted audio from what you hear in the earpiece, leaving only a bit of "sidetone". Too little of that, and the phone appears dead. Too much and you distract yourself with your own voice.

https://en.wikipedia.org/wiki/Telephone_hybrid

I wish cellphones had sidetalk.

Many of them do. My Android 9 phone has it. The feature only turns on when your calling an actual phone number though, voice calls like Discord don't trigger it.

It's not analog, but it's a feature built into the audio chip so there's no noticeable lag. AFAIK, it's not exposed to other software at all, because even the official Google Sound Amplifier app has noticeable lag since it does it in software.

My Samsung S10e (Android 12) doesn't do it—I made sure before making that comment. I didn't know that some Android phones do have sidetalk. In my experience talking on a landline, sidetalk makes talking much easier for me, more real somehow. Talking into my cellphone is like talking into the void, and I avoid it whenever possible.

I've never actually listened for it, but for sure audio calls (on a Moto G Play 2021 in my case) are less than satisfying. As a result I nearly always (except when privacy matters) use it in speakerphone mode.

Technology 40 years ago was so simple, that anyone with basic education in electronics could understand how this or other basic utilities work and when opened up could identify which component does what and if you identified a faulty component you could often easily replace it and thus repair it on your own, and skilled individuals could probably make their own from scratch if they could source all components and didn't care about patents....

Nowadays even the products which didn't evolve much since then are often made very hard to repair + new technologies are increasingly more difficult to understand and state of the art technology in some areas is so complicated that we're literally dependent on one or two companies who can make it for us (3nm chips for example, or web browsers in software)..

It will be very interesting to follow how much the complexity will increase in the next 40 years..

Indeed. I always figured that even if the cost to manufacture has gone down for any given piece of electronics that cost to society has actually gone up because instead of repairing things (which also provided jobs) they are now discarded far earlier than they would have been in the past.

Much earlier in my life I earned some money on the side repairing electronics and while it is of course still technically feasible the number of one-off components in any given device is so high and the documentation and repairability so low that it just isn't worth it. This was not a good development, but it seems we're stuck with it. The one big plus from all this integration is that devices consume far less power than they used to.

It's like cars. Decades ago you might see your local mechanic once a year (if you're lucky) or multiple times a year to fix issues with the car, nowadays there's a good chance a new car will go 100k miles with only wear-and-tear items needing maintenance done.

But if they break you're in for a world of trouble, and you will in one go end up offsetting a good chunk (or more) of what you saved up to that point. In a way this is the result of designing things to outlast their warranty, once the warranty period is over anything that still works was essentially overdesigned. Fortunately for cars and other high ticket items the secondary market will punish brands that are playing it too loose and too fast but I've seen pricing for for instance headlight or taillight assemblies that make you wonder if there is an error.

My mom's fridge broke exactly one day after the warranty expired.

She was crying on the phone, then they said they would honour the repair anyway.

That made her happy again.

Old cars had more maintenance requirements and were far less reliable, but repairs tended to be simpler.

For example, you may need to tune your carburetor seasonally. Old points based distributors needed the points adjusted or replaced. Simple tools like a screwdriver and a matchbook can get those two sorted.

Fuel injection and electronic ignition eliminated a lot of regular maintenance, but they are harder for the average person to troubleshoot, let alone repair.

Gone are the days where a rough idle could be fixed with a screwdriver. But so too are the days where a mountain pass requires that same screwdriver to be pulled out on the way up and the way down to adjust the fuel-air ratio.

I have a car maintenance manual from very early in the 20th century (1910 or something) and the maintenance schedule it describes would be ludicrous nowadays. It talks about changing the oil and greasing all of the joints every couple hundred miles, for example. At the same time, there are some components that are essentially the same now. Based on the diagrams, it looks like the wheel hubs and bearings would be compatible with the ones on my modern boat trailer.

The bearing might be compatible, but new ones are so much better. The slop (if that’s the right word) in bearings manufactured 50 years ago was more than you get now.

I'm not a serious mechanic, but I suspect one of the reasons the bearings and shaft on the hub are tapered is so you can tighten it down and accommodate for minor variations in the tolerances. That would have been more important before it was all being done with CNC. The material for the bearings was probably not super either.

Things that have changed in bearings: better materials science led to more understanding of how you can harden surfaces and this in turn led to better 'races' in bearings as well as balls and rollers that are harder leaving bearings that last longer in principle. But all that wouldn't matter one bit if the bearings weren't sealed properly and that's the second improvement that led to longer bearing life. Finally, the third factor, improved lubricants, better able to deal with thermal cycling and high heat.

My Dad, born in the early 1930s, said that on any lengthy drive (I'm guessing > 100km), you just assumed that you would have at least one puncture or other minor breakdown.

He and his cousin were given a car with a wooden body; once the engine overheated and it burned to the ground.

Punctures... there is a good point! I haven't had one in years (let's not jinx this...), but in the past, up to the late 80's I would have them with some regularity. I suspect that the improved quality of the roads is also a factor in this.

I strongly believe there was a optimal point where it was both relatively straightforward to service vehicles (or possibly easier), and their reliability was much better than what preceded them (and frankly also what came after): probably in the 90s or very early 00s. An example I would kind of think of, was GM's throttle body injection, or some of the simpler port fuel injection systems and the engine and transmission technologies concurrent with these. They have basically all of the advantages of EFI, such as behaving correctly with altitude changes, not rampantly over or under fueling the engine (because of the feedback loop with the O2 sensor, etc.), while retaining the same simplicity (or better) than their predecessors. Ignition was kind of the same way: HEI distributors, and even better, wasted spark systems, are absolutely dirt simpler, and really simpler than points and condensors, while being much more efficient and robust. The electronics on these are relatively simple, well understood (basically anyone and their bother has been able to tune and flash a lot of GM EPROMS/EEPROMS for a long time now), have replacements that are also better and open (Megasquirt and similar), and very robust.

A lot of the newer technologies, like variable valve timing, are cool, but you can still have (and did for a time) a lot of the ease of service, with much better running behavior and reliability. We can have our cake and eat it, manufacturers are just apparently very incentivized against this.

I strongly agree with your assessment. You can have a lot of fun and reliability with circa 1995 technology combined with modern manufacturing techniques.

Much of the newer stuff is about meeting emissions and fuel mileage mandates. There's a reason VVT lockouts are a thing in the aftermarket

But both restricting emissions and improving fuel mileage are good things, right?

Comparing state of the art semiconductors to web browsers feels like an insult honestly

In my opinion browesr are just huge mess of shitton of technologies that are constantly changing/moving, yet fundamentally it is just about processing some letters, executing some code and drawing colors on the monitor.

Nothing novel that we weren't doing before or in other software (OSes, compilers, etc)

Meanwhile semico feels to be close to the limits of the physics.

" just about processing some letters, executing some code and drawing colors on the monitor"

Sure, nothing more. Except that this drawing colors on the monitor is plattform independent and used worldwide for all kinds of sandboxed applications and is the plattform for most commercial transactions and normal communications now. So quite trivial and surely anyone can do it.

Sure I made it sound trivial, but that's in the context of comparison with state of the art semiconductor engineering.

Semico. engineering is current "rocket science" of 70s.

Cross-platform GUIs aren't novel. Frameworks for this shit probably appear every year and are as messy as existing ones.

It's a mess, hard mess, but not novelty, not the edge of science / engineering. The problem is to get people to agree on something.

>and is the plattform for most commercial transactions and normal communications now

What's so novel about it? SMS or even your Master/Visa cards were doing it for decades

IRC, Email too.

And of course still: we were using Web browser as platform those things for decades.

It's not a bleeding "edge" technology in $currentYear.

WebAssembly ecosystem? yet another collection of VMs/Compilers/Intermediate Languages?

We were doing it for decades.

>sandboxed applications

Ok, that's fair point - there's novelty needed.

Very often because we try to write technology that's... easy to fuckup? idk - check how huge % of CVEs is related to JIT compiler

or because we write it in unsafe languages - check how huge % of CVEs is related to mem. issues.

But yea, I agree on security - stuff like postquant crypto and other protections.

> Semico. engineering is current "rocket science" of 70s.

Even rocket science is just Newtonian physics, for the most part.

That's the theory behind, the execution is hard.

Meanwhile, unlike moon-landings - we're constantly doing web browsers:

there was IE, there was Edge, there is Firefox, there is Chromium and its forks.

There are smaller browsers with less resources than Google.

Yet, we are not trying to figure out how to make web browser possible.

We know how to do it, we are doing it for decades.

It's just hard due to reasons - money, effort required, moving target, backward compatibility, and probably many other.

Can same be said about semico? Do we know what needs to be done to reach "state of the art" for year 2033?

Do semico competitors know their roads to match its competitors capabilities 10 years from now? I dont think so.

I get what you mean, but my original thought was about complexity as in how much effort (work & time & money) would it take to re-create the thing and start a competing business, given you already have all the necessary knowledge. Cause it increasingly feels like working on state-of-the-art is only achievable by big players...

Under these assumptions it's not really being bleeding edge, how much research went into it, or how hard of a science is behind that make it complex, but rather the amount of components and parts needed to assemble it (and in case of hardware also the rarity of them). When I am talking about state-of-the-art technology there I just mean the newest competitive version of a thing that most people use daily...

Modern browsers have code execution environments that very much push the state of the art in compilation and os-like capabilities.

>Modern browsers have code execution environments that very much push the state of the art in compilation

By which metric?

Well, I’m not a practitioner in that space, and maybe my perception is out of date.

But didn’t the semantics of JavaScript lead to some pretty novel ways of just-in-time compiling code at runtime? When the V8 engine was introduced, for example.

Maybe, maybe, there will be a compression/folding event, that squashes all the useless complexity into simpler artefacts.

"useless complexity," spoken like a true software engineer.

Yeah, the beauty of simplicity... but OTOH, you had to dial all those phone numbers by hand, the quality for long distance calls was sometimes so bad that you had trouble understanding anything at all, when the phone rang, you had no idea who was calling (or who had called when you didn't get to the phone in time) etc. Newer technology is orders of magnitude more complicated, but it enables you to transmit not only voice, but also several Mbps of data over the same two thin telephone wires.

Or WiFi. Or the USB protocol.

> Technology 40 years ago was so simple, that anyone with basic education in electronics could understand how this or other basic utilities work and when opened up could identify which component does what and if you identified a faulty component you could often easily replace it and thus repair it on your own,

You’ve never seen an ISDN phone then (came only a few years after this one was made)

I have a Siemens phone that's similar to this (I turned it into a mobile phone). When I opened it up, it had a leaflet with the schematics of the entire device inside.

You make the case for the GPL very well.

Can't believe to see my hometown (Stropkov) on Hacker News!

Here's official website of Tesla Stropkov: https://www.tesla.sk/

The phone from the article can be seen in the local museum: https://www.tesla.sk/stala-expozicia-tesla

Stropkov is a small town (population of 10k), relatively poor in EU standards. Tesla Stropkov is still the biggest employer here, so big, that when the shift finishes, there's traffic jam!

If you have any questions, feel free to ask!

Makes me want to visit.

The real Tesla! Sorry, I'm biased my grandma worked there. Their radios were also very stylish

This is a telephone hybrid: https://en.m.wikipedia.org/wiki/Telephone_hybrid

Yes, agreed, but I'd love to know the pinout.

Probably some variation on this one: https://www.teslakatalog.cz/WNB066.html ?

Thank you.

When things came in colours

You should chech out the Iskra ETA 80 (1980) from Yugoslavia, which was plagiarised in the USA:

https://www.tms.si/en/the-bramao-and-iskra-eta-80-telephones...

So not a built-in car phone of a Tesla vehicle. This one is indeed nice. The color is so 1970s.

This was the very first telephone model we had at home and was in use until about 10 years ago when we cancelled the telephone service. The actual telephone is still sitting in a closet somewhere.

Beautifully designed. Flashy hot orange, Curved like a woman. Wonderfull

Few tactile experiences are more satisfying than turning the dial of a nice rotary phone. I feel bummed that most young people have missed on this little pleasure.

Sort of? Having a friend with a phone number that required several full rotations made them deeply irritating.

The classic US area codes (those with a 0 or 1 as the second digit) are a snapshot of 1940s demographics. The most important cities at the time got the smallest numbers.

https://www.lincmad.com/map1947.html

Are the silver axial capacitors in the handset (near the C2 designator) wet tantalum slugs? Or do they just look similar.

It's always weird looking at communist electronics because their components are like an entirely different ecosystem. Nowadays you have 100 companies making electrolytic capacitors but they all look identical outside the colors. Same story for pretty much every component. It's strange seeing anything different.

Though this one looks pretty standard.

These are just normal aluminium electrolytics. Usually these had outer plastic sheath (which makes the package look uninteresting), but they did not have to (AFAIK there were three separate ordering codes for sheath, no sheath and random, with there price slightly decreasing in this order).

What are those two big brown cylinders? More capacitors? What did they need big capacitors for?

Classic dial phones have no active components and no capacitors. Western Electric loved inductors. If it could be done with an inductor, they'd do it that way. Inductors don't fail unless physically damaged.

Those are almost certainly capacitors. They look like metallized plastic film capacitors, though they could be strange-looking communist electrolytic or something else.

Film capacitors are non-polarized, and are available with high voltage ratings. I don't have a great understanding of how old analog telephones work, but I expect that they are being used as DC blocking capacitors on the pair of telephone lines. I think telephone lines provide ~50V DC to power the handsets. Telephone lines are also vulnerable to various higher voltage electrical faults like lightning strikes. So those capacitors would block any DC voltage, while allowing the AC signal to pass through. They need a relatively high capacitance in order to let low frequency sounds through.

I did a bit of looking. Phone lines, at least western ones, did provide 50VDC. Some rural loops used range extenders at 100 or 130VDC. They also applied 20Hz 90~150VAC to ring the phone.

So those could be DC blocking capacitors for the signal. They could also be for the ringer, where they'd block the DC to prevent burning the coils out, and pass the AC through. You'd need a relatively large film capacitor to pass ~10mA 20Hz 150V with safety margin.

If anyone knows the pinout of the WNB 068 I'd love to hear about it.

https://elparts.mekweb.eu/ds/WNB068.jpg

That drawing is marked "WNB 067" ... previous iteration maybe?

the two wires to the handset and 4 to the dial confuse me there, too. IIRC its the other way around, isn't it?

No, it matches the picture: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj...

Handset being the 2 conductor wire exiting the picture on the right/middle.

Note the '/ 068' behind it!

Yes. Not seen in my photos is that behind the WNB 068 printed on the PCB is WNB 067.

The WNB prefix means that it is an custom application specific hybrid (as in "thick film on ceramic") module, that pretty much means that there never was any kind of documentation for the part. Obviously the function of the thing is that it implements what is called "phone hybrid" (completely different meaning of "hybrid") in solid state without magnetics.

Looking at schematics of what is inside the handset it seems to me that it does not even make much sense to think about a pinout of the thing, because most of the pins are used to connect external components that could not be efficiently integrated into the module (essentially a handful of capacitors and overvoltage protection network).

Given the peer comment with the schematic, it does feel like there's more you can gather. It appears, for example, that there's a "push to amplify" button on the handset that's not pictured in the post...it doesn't show the other side of the handset where that button probably is.

Shown as "-( 21 S 22 )-" on the schematic, bottom left. The wedge shaped metal tab you can see on the backside of the open handset is probably the spring+contact for that switch? So the IC also appears to have an amplifier.

The "-( 21 S 22 )-" thing is a speaker in the handset. The button is above that, labeled "VAR.".

Probably the main reason why essentially the entire electronics is in the handset and why it is somewhat complex is that it does not use carbon microphone, but the microphone is actually the exactly same part as the speaker, used as an dynamic microphone (with the required amplification being done by the hybrid module).

Ah, yep. I had seen phones like this with the pushbutton, so fooled by past expeirence.

I didn't realise that there was a Tesla before Tesla.

It was a state-owned electronics company which pretty much ceased to exist after the fall of communism because the products were far behind western and Asian. Some subsidiaries still exist under different names.

Edited: apparently Tesla Stropkov still exists under its old name, and even owns the tesla.sk domain

Tesla Stropkov was just branch. We had this phone at home but also products from Tesla Bratislava (like PMD) or Tesla Praha.

Interesting that Tesla Stropkov is still existing and has retained Tesla logo. I always forget that there is still something in the east (of Bratislava).

There technically never was a “Tesla Inc.” with separate branches. There was a bunch of essentially unrelated companies named “Tesla something” that used the same brand and (obviously) traded with each other. There was similar pattern with “ČKD” and “Škoda”.

Some of these companies still exist under the original name (eg. Tesla Stropkov), some ceased to exist, one of them did slight rebranding (Teco = TEsla KOlin), some of them did more extensive rebranding and restructuralization and some of them were integrated into multinational electronics manufacturers (Philips, Motorola, Infineon, TDK, Sony, Foxconn…). Somewhat interestingly the part of Tesla that originally was Czechoslovak branch of Philips is today owned by NXP, but it didn't happen directly but through Motorola and Freescale.

I genuinely miss having a POTS telephone attached to the wall. Anyone have a recommendations on recreating the experience in the modern age?

It’ll be VoIP behind the scenes but you can get these small boxes that basically give you a phone jack on one end and encode everything as VoIP. The phone connected to it sees a POTS and has no clue it’s VoIP. Kinda like how it’s done with most ISPs boxes that give you internet, tv, telephone.

I think you can still request a POTS hookup from the carrier but that can’t be cheap and it’s VoIP shortly after anyway, it only makes the copper pair to the VoIP box longer than if you do it yourself.

See I knew Tesla was going to make a phone.

Gotta love jgrahamc is still using blogger.

Every now and again I think about changing to something else. Most likely a static generator because there are things about Blogger that I dislike (its handling of images, for example) and then I think two things:

1. I'll have to spend forever messing around getting the import right.

2. I'll discover things I dislike about $NEW_THING.

And so I stay with Blogger which, apparently, I've been using since 2005! Maybe now that it's been 18 years it's time for a change? If I did change, what should I use?

At some point I looked at using Hugo and discovered that there are four different "import from Blogger" tools. No idea which one is the best/works etc. so I was put off.

We had this phone at home :) heh

had the same :D

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