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From: randyd@csd4.csd.uwm.edu (Randall Elton Ding)
Newsgroups: rec.audio,sci.electronics
Subject: Re: ADCOM GTP500II IR sensor & repeater spec's?
Date: 21 Apr 1993 04:25:36 GMT
Organization: Computing Services Division, University of Wisconsin - Milwaukee
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Message-ID: <1r2ic0INN72i@uwm.edu>
References: <1r1996INNijp@hp-col.col.hp.com>
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In article <1r1996INNijp@hp-col.col.hp.com> johnr@col.hp.com (John T. Rasper) writes:
>Does anyone know the details of the interface (5 wire din) for the
>IR remote sensor & (2 wire IR repeater) for the ADCOM GTP-500II
>preamp?  The ADCOM part numbers are the XR-500II, SPM-500II, and 
>IRA-500II.
>
>A cursory physical examination of the pre-amp connector indicates
>that the connector (5 pin din) may provide: (Viewed from connector front)
>
>      |
>   5     1     (pin ?) +?v @ ???mA
>    4   2      (pin ?) +/-?v @ ???mA
>      3        (pin 3) Signal Ground
>               (pin ?) Demodulated signal ?V-pp, ? polarity, ? mA drive
>               (pin ?) Signal to drive repeater LED (drives through 150ohm
>                       resistor) ?V-pp
>
>I assume that the repeater connectors (mini-plugs) drive the IR repeater
>LED's directly.  True?
>
>Can anyone fill in the ?'s.  Thanks.
>

Here's the scoop.  When you get your home brew receiver working, would
you be willing to share it with the rest of us?  I always wanted to
build my own but never have the time to fool around and design it.

pin 1:  signal ground
pin 2:  signal
pin 3:  always hot +6 volts
pin 4:  +6 volts, hot only when preamp is turned on
pin 5:  infrared repeater connectors

The infrared repeater jacks on the back of the preamp are not connected
to anything inside the preamp except the 5 pin connector pin #5.  There
is a 150 ohm resistor between the two jacks, with a 1.5K from pin 5 to
ground.

The signal pin #2 in the preamp is summed with the built in IR receiver.
They use a chip called CX20106A and a BJT to amplify the signal.  I would
imagine the logical way would be to duplicate this circuit and use
it as the external receiver.

If you need more info, let me know.

Randy      randyd@csd4.csd.uwm.edu