Acoustic Data Coupler

[R1ch514]

In a second hand/junk shop near to me I've come across an item which I've never seen before. It's an 'Anderson Jacobson ADC 212' which is described as an Acoustic Data Coupler. I believe I'm in the right forum here to ask if anyone can give me an idea as to what it is and how it works. Google search is a bit sketchy. I'm just a bit intrigued by it.
Rich.

[paulsherwin]

Acoustic couplers were computer modems which didn't connect electrically to the phone system. Instead the phone handset fitted into cups at each end of a cradle. They date back to a time when telcos didn't allow direct connections, and phones were hard wired rather than socketed.

Most ran at 110 or 300 baud (about 11 or 30 bytes per second) and they were common in the 70s, but the acoustic coupling made them prone to errors, which combined with a lack of error correction in the protocol made them unreliable in use. They were quickly superseded in the 80s.

[RogerEvans]

Back in the late 1970s we had a 'portable' terminal at work that you could take home on the pretence of needing to check your batch computing jobs at the weekend. I think it was made by HP, weighed around 20kg or more, had a 300 baud acoustic coupler and a thermal printer rather than a screen. You only got to check a few lines of output but at least you could change any obvious mistakes and save another 24 hour batch job turnaround.

I won't say 'happy days' but it certainly was different! It might still work today with a suitably shaped handset and an old PC modem set to 300 baud at the other end.

Roger

[Phil G4SPZ]

The GPO were very strict in those days about third parties making direct connections to their network. I once had a 'Juliphone' telephone answering machine which used a similar acoustic coupler; the handset was placed into the coupler, the telephone itself sat on top of the answering machine, and an electromagnet-operated arm lifted and depressed the cradle switches. It had a loop of tape for the 15-second outgoing message, and 3" reels to record the incoming messages. But I digress...

[R1ch514]

So probably more use as a museum piece then. Found it in one of those shops that sells stuff for you and takes a percentage. Can't imagine it would ever get sold. Firstly - no one will know what it is, secondly - it's of absolutely no use to anyone nowadays.
Thanks for telling me about it though, it was a new one on me.

[G4_Pete]

Hi,
" it's of absolutely no use to anyone nowadays."

That is is a broad statment on this forum !!
Pete

[dagskarlsen]

It is at least a few people wanting this for collecting and use together with really old stuff.
I am pretty sure it has been up at this page: http://www.classicrotaryphones.com
dsk

[Dave Moll]

Originally Posted by RogerEvans

It might still work today with a suitably shaped handset and an old PC modem set to 300 baud at the other end.

Most probably, the cups will be designed to fit a 700 series telephone.

[GMB]

Yes, I used these. In fact I still have one and use it every day. Even as I type this!

OK, it makes a handy foot-stool for my desk.

As said above they could do 110 or 300 baud (that's 10 or 30 cps, there are 11 bits in the 110 baud frame). I found them pretty reliable at 110.

[richrussell]

Watch some of the classic early 1980s films such as War Games, Weird Science or Ferris Bueller's Day Off - you'll see people plonking telephone handsets into acoustic couplers and watching text appear slowly (usually with a ticking sound) on their green screen monitor.

Small acoustic couplers existed for laptops too. I had one that came with an Atari Portfolio (with its built in 300bps modem) at one point. Not much more than some elastic straps and a couple of piezo transducers.

[russell_w_b]

Used to have one on the BBC MIC (Monitoring and Information Centre) at Kirk o' Shotts back in the early 1980s. I seem to recall it being used with a Commodore PET computer that stood alongside.

Also on the desk was a 'Fault Resetter': a little box with a 4T rocking armature inset receiver in it that was placed over the mouthpiece of the telephone to send tones to the appropriate transmitter relay Auto Fault Reporting apparatus to reset certain faults.

It was banned at one time as it was possible to reset faults in a casual manner with serious consequences!

[AndiiT]

Hi,
My ex brother in law used an acoustic coupler back in the early 80's to connect his Amstrad 1512 PC to some mainframe or other, I thought that his connection speed was around 8k but looking at other posts it was most likely 110 baud.

The coupler that he used had a quite flexible "spine" which allowed differing designs of handset to be used as liberalisation of the PSTN was beginning to take place in 1981 and more modern designs of phone were appearing to rival the 700 series telephones.

Any instruction that he sent to "destroy gnome number seven" (he was an on line gamer even back then) would take around half an hour to reach its destination which was fine if you were playing against someone connected in a similar fashion to another rural exchange, but if you were playing against someone in London who would be connected to a number of servers in close proximity, gnome number seven may well have already been slain by someone with a "faster' (closer) connection to your opponent before your instruction reached its destination

Regards

Andrew

[G6Tanuki]

The Anderson-Jacobson acoustic couplers were standard issue for generic 'field staff' back in the late-1970s and early-1980s; they could be coerced into fitting the handsets of most states' phones of the era.

1980s GDR telephone-exchanges were rather good at detecting the modulation-patterns of these, and dropping 'international' calls. The Texas Instruments "Silent 700" series of acoustically-coupled terminals were ~~~~allegedly~~~~ better at evading detection.

[russell_w_b]

I found this 'Display Electronics' advert in a 1985 'Wireless World'.

[Refugee]

I can remember using 110 baud one in the late 1970s at college to access the OU mainframe.

[Dave Moll]

Russell, I would have been wary of buying from a company that can't even spell "acoustic".