>>> So, I really do need this device. Any help would be greatly
>>> appreciated. Sorry for the [OT] posting.
>> I'll have a go at designing one for you, but don't hold your
>> breath.
> That would be great! I figured a few rectifiers, a zener, and a
> few other parts should do it, but I've been away from
> electronics for a few years and don't have the time to fiddle.
> If you come up with something, I'd be very grateful indeed!
Power supply section:
Q> L >----oxo------* +-------+
Q> F1 / \ +-------*----| 74L05 |----*-----< +5v
Q> - / \ + | | +-------+ |
Q> 8-12V +-* BR1 *---* | | |
Q> 150mA | \ / | + === C2 | C3 ===
Q> | \ / === C1 | | |
Q> N >--------|----* | | | |
Q> +-----------*-------*--------*--------*-----< Gnd
Line condition detector section:
Q> /|
Q> / | R1
Q> / -|-----*---------v^v^v--------< +5v
Q> RING >--------*-----< A | |
Q> | \ +|-----|-------------+
Q> | \ | | |
Q> +-----+ \| < |
Q> OFFLINE >----o| NOR | R2 > |
Q> +-----+ /| < |
Q> | / | | |
Q> | / -|-----|-------------*
Q> ONLINE >--------*-----< B | | |
Q> \ +|-----*-----v^v^v---|-------------+
Q> \ | R3 | |
Q> \| | |
Q> +-----+ | |
Q> Tel B >-----| I |-----------* | |
Q> | S | / \ | |
Q> | O | - / \ + | |
Q> | L | +---* BR2 *----v^v^v----*----v^v^v----*
Q> | A | | \ / R4 R5 |
Q> | T | | \ / |
Q> | O |----|------* +-----------+
Q> Tel A >-----| R | | |
Q> +-----+ +-------------------------*-----< Gnd
Instructions:
1. Connect L and N to your power supply, which should deliver 8-14v at
100mA, either AC or DC is OK and polarity not important.
2. Connect "Tel A" and "Tel B" to your telephone line.
3. Connect OFFLINE, ONLINE and RING to your favourite parallel port as
required.
4. Select R1, R2 and R3 such that the junction R2/R3 is between +1.0v and
+1.5v, and the junction R1/R2 is between +2.5v and +2.7v, both being
relative to system ground. Actual values are unimportant so long as
these ranges are met, but current requirements depend on the two
comparators A and B.
5. Select R4 and R5 such that R4 is 24 times R5. Current rquirements
again depend on the two comparators A and B.
Best wishes from Riley.
+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html
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