Whats Inside a Phonenet Adapter?

[benjgvps]

I got a Phonenet adapter from a friend a while back and he said hen only had one. It looks to me like the box just has the pins on the serial cable hooked up to two phone jacks. I want to create an adapter from the null modem connector (Mini din 8 to Din 9) to hook up my two PowerBooks by using two phone cables hooked up to a Din 9 connector which is connected to the Phonenet adapter. Would this work?

 

[Anonymous Freak]

You can just use a standard Mac 'printer' serial cable between the two systems. The only reason to bother with PhoneNet for only two computers is if they are too far away from each other for a standard serial cable. You don't even need a null modem cable for AppleTalk networking. A perfectly standard serial cable would work fine.

 

[beachycove]

My phonenet adapters have a small circuit board inside.

 

[Charlieman]

You've lost me... What do you wish to connect to what and how? I suspect that Anonymous Freak may have provided an answer.

 

[benjgvps]

What does the circuit board have? any chips or does it just have the pins going to the phone jacks?

 

[Mac128]

PhoneNet is just another term for LocalTalk. It used phone cables and connectors instead of mini DIN-3 cables

This is basically how to build your own:

http://www.jagshouse.com/localtalk.html

 

[tomlee59]

I'd go with Anonymous Freak's suggestion. If all you want to do is connect two macs to each other, by far the easiest method is to use an ordinary serial printer cable to hook them together. So, unless you can't find one, or otherwise enjoy piecing things together, I'd strongly recommend the printer cable method. I use it all the time.

 

[Anonymous Freak]

PhoneNet is not "just another term for LocalTalk"...

LocalTalk is the name of the serial protocol itself, regardless of physical medium. PhoneNet is one implementation of LocalTalk, that uses dongles and standard "Cat 1" telephone wires.

This is much the same as how "Ethernet" describes the protocol, while "Coax" or "10Base-T" describes the physical implementation. (Heck, if you really felt like it, you can even run Ethernet over standard four-conductor telephone wire, although it takes a lot of tweaking.)

The whole OSI 7-layer networking model may be goofy, but it does delineate the separate parts. (For example, "TCP" and "IP" are two separate protocols, on two separate layers, that are not at all dependent on each other, in spite of the common usage of "TCP/IP".)

Another thing is that PhoneNET caps out at the 230 Kbps of the native speed of the RS-422 serial port in the Mac. With the original Apple 3-pin mini-DIN adapters, LocalTalk can be externally clocked up to 2 Mbps. (The same speed as coaxial Ethernet.) I used to work in an office that used one of those external clocking adapters, and when I went back to PhoneNET, it was excruciating to run apps off a network server. (Since 2 Mbps was faster than the internal hard drive on some SEs, and faster than the Plus' SCSI is even theoretically capable of!)

 

[benjgvps]

The reason why I'm asking these questions is because I do not have access to another printer cable, the one I have is chopped up so I could make a null modem cable (PC to Mac). That was before I got the other machine. I want to know if the PhoneNet adapters are just wires going from the serial cable to the phone jacks.

 

[beachycove]

I do not know the technical details, but I have a dead phonenet adapter that I took apart to see if it could be fixed (assuming what you are assuming, I was merely looking for loose connections, etc.), and yes, I did discover that there is a tiny bit of circuitry in there, mounted on a small board. That is what had gone kaput, rather than some soldering or whatever.

This is not to say that straight wiring along the lines of a serial cable could not work (presumably a set of telephone wires stuck in the relevant serial port holes, as if it were a cable, might work, but it would be less than ideal, to say the least). What it suggests, however, is that phonenet was something more than a wiring bridge/ connector/ plug.

Phonenet adapters can be bought for very little, so why not just pay for some? I have none to spare, but somebody on this list surely does. Post a WTB in the relevant forum.

 

[Mac128]

PhoneNet is not "just another term for LocalTalk"...
LocalTalk is the name of the serial protocol itself, regardless of physical medium. PhoneNet is one implementation of LocalTalk, that uses dongles and standard "Cat 1" telephone wires.

My apologies for not being clear enough. PhoneNet CONNECTOR is just another type of LocalTalk CONNECTOR. Your clarification is of course enlightening but as benjgvps points out, not very helpful.

In any event, my point is that these boxes have internal hardware and are not just a converter to an RJ-11 connector. The LocalTalk connection module contains a transformer.

As beachycove points out, you do not need an actual LocalTalk connector (PhoneNet or otherwise). You could construct a serial cable by just shoving wires into the mini DIN-8 connectors, matching the serial pinouts. However, that introduces a WIDE margin of error. You need 4 wires, wire pins 3,5,6 & 8 pin-to-pin, instead of the two used by the LocalTalk connectors (and PhoneNet connectors).

As both beachycove and tomlee59 point out, your best bet is to go buy yourself a printer cable or another phonenet box, which can be found quite inexpensively on eBay.

Good luck.

 

[Flash!]

Mini DIN8's are a b@#$ to solder

I'm on 'Freaks side - I think it is important to know what protocol you are playing with before you start soldering adaptors...so I don't think he was being unhelpful [V]

The problem with just poking a few wires in and seeing what happens is that you can end up sending voltage the wrong way to the serial control IC, blowing it up and spending the next 5 hours on a fruitless effort to connect two Macs together.

 

[benjgvps]

Sigh. Is there a decent non-auction site that ships to Canada that still sells Mini-din 8 cables? I think I saw one on a digikey (Electronics parts maker) type site, could have been digikey.

I just had a weird thought: Could you use one of those Roomba to BlueTooth adapters for sending files between Mac-PC like I would do with a null modem cable. I think they show up as a serial port when connected to the computer that the (Bluetooth) adapter is connected to.

 

[Mac128]

benjgvps, I think it's time you let us know what exactly it is you are trying to do. One of your PowerBooks has USB AND a SERIAL port?

All you need to do is GOOGLE Apple Imagewriter Cable and you will come up with numerous vendors around the world who still sell mini DIN-8 printer cables for the old Mac. Not sure why you are opposed to an auction site, as eBay has many buy-it-now vendors which do not require an actual auction to purchase.

But if you have USB, depending on what you are trying to do, there are all kinds of options now. FYI, unless you are trying to NETWORK your PowerBooks, you should be able to use SCSI DISK MODE to use one of them as a hard drive for the other. Like I said, all kinds of options.

 

[~tl]

benjgvps, I think it's time you let us know what exactly it is you are trying to do. One of your PowerBooks has USB AND a SERIAL port?

When did USB come into this?

 

[Charlieman]

Another thing is that PhoneNET caps out at the 230 Kbps of the native speed of the RS-422 serial port in the Mac.

True, but you can increase PhoneNet bandwidth by using a star controller. A well designed star configuration on a fast back bone will deliver the entire 230Kbps LocalTalk rate to all attached devices. We used this method up to mid 1995 to run a small lab of SEs. It was fine for running small apps like Word 5.1 and Excel 4 from a file server.

A bit of network history that you might appreciate:

http://www.net.cmu.edu/docs/arch/article2.html

 

[benjgvps]

Where did I mention USB? I also am giving up on the original question because it was answered. The question I posted above about the Roomba to Bluetooth adapter, I want to know if I could buy/build one of the adapters and plug it into one of my PowerBooks (The cable that connects to the Roomba is a Mini-Din 8 cable) then connect to it with a PC that has a Bluetooth adapter. It should work, the interface is just serial.

 

[register]

Another word to clarify the operation of a PhoneNet adaptor: it allows to connect several Macs and other LocalTalk capable peripheral devices at a time. It allows to set up reliable mid-distance connections of up to several hundred metres, using the cheapest possible kind of wiring. The probably most important feature of the tiny electronics inside the adaptor is to maintain an electrical band pass operation: it must block out low freqency current (DC), like driven from a grounding offset in the line power supply of distant located Macs. It should not allow to pick up high frequency noise from the environment.

High quality adaptors use transformers, there ist also a cheap alternative called CapNet, which uses just a capacitor.

P.S.: some LocalTalk capable devices for the Macintosh decide which protocol to use by an electrical check of the serial connection (like the HP DeskWriter C). It uses a standard serial protocol if connected with a standard printer cable, and the LocalTalk protocol if connected with a LocalTalk adaptor. In case you need a single local connected device of this kind to behave as a network device (and there are cases, where this is necessary), it is possible to spoof a LocalTalk connection by preparing the standard printer cable with a Resistor of about 1000 Ohms, connected from Tx(-), Pin 5, To Tx(+), Pin 4 on the Printer's side of the cable. For details look at:

http://www.fortunecity.de/wolkenkratzer/486/60/cap3.htm