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Thread: 5 pin DIN current loop pinout?

  1. #1

    Default 5 pin DIN current loop pinout?

    Hi all,
    I'm still having fun restoring the two '70s acoustic couplers. They have both an RS-232 interface (DB-25F) and a 5-pin DIN (not a common type, no center pin, all pins spaced evenly on 360 degrees).
    I'm guessing it's for 20mA current loop, all 5 pins have a wire connected.
    I've so far reverse engineered the DB-25F pinout and looks like a standard DCE with not many signals (TX,RX,CTS,DSR,DCD,GND).
    Is there a standard for these 5-pins DIN connectors that anybody is aware of?
    Thanks in advance

    Frank IZ8DWF

  2. #2
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    That sounds like what at the time was a common microphone connector. But not having one in front of me I don't recall if they were a circle of 5 or a circle of 6 with one omitted.

  3. #3

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    Quote Originally Posted by KC9UDX View Post
    That sounds like what at the time was a common microphone connector. But not having one in front of me I don't recall if they were a circle of 5 or a circle of 6 with one omitted.
    Well, yes, actually if we count the shell contact, it's 6 pins in a circle. The shell contact isn't used anyway.
    I'm not too worried about finding a mating connector, I wanted more a second source of the right pinout, to double check my
    reverse-engineered guesses.
    Frank

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    What I mean is a circle of six with one omitted would mean pins at relative angles of 60. A circle of five has pins spaced a 72. I'm pretty sure there's no standard for DIN connectors with five pins at 72. I think I have seen them on Europoean (especially German) machine tool components, but nothing that would be a standard that I'm aware of.

    The more I think about it, the microphone plugs were probably all 60 spaced. But I don't think even those were standardised. I'm pretty sure I've had to rewire those when swapping microphones between different equipment.

  5. #5
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    MIDI uses Current Loop on 5-pin DIN.
    https://en.wikipedia.org/wiki/MIDI#Connectors

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    Quote Originally Posted by alecv View Post
    MIDI uses Current Loop on 5-pin DIN.
    https://en.wikipedia.org/wiki/MIDI#Connectors
    Completely different connector though. Not compatible. And MIDI wasn't around in the 70s, nor would it ever apply to a acoustic coupler modem.

  7. #7

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    Quote Originally Posted by alecv View Post
    MIDI uses Current Loop on 5-pin DIN.
    https://en.wikipedia.org/wiki/MIDI#Connectors
    I've seen the MIDI pinout and it's nothing like what I found by reverse engineering one of my acoustic couplers.
    I have reversed almost all the complete schematic of one of the couplers so far, so getting the DIN pinout was easy in the end. It has two loops, one for RX and one for TX, the two loops can be connected in series for half duplex operation, one of the pin goes to common GND. If I find the same pinout on the other coupler, I know it's right
    I'm currently waiting (for more than 2 weeks now) for a small package of ME4101 transistors from the UK, I need just one to complete the coupler repair and start testing it. Of course I could have used any common BC547 in place of the ME4101, but I thought I'd use a vintage transistor.
    Italian post service is really trying to kill anything like old unregistered letter service, I hope other countries aren't *so damn bad*

    Frank IZ8DWF

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