Schematics as they stand, 3 pages so far.
It needs a 12v/1.5A wall wart supply to properly run up to 4 phones.
Empirical tests with my VOM monitoring the 12v power consumption (+/-10mA) with 4 phones and 2 lines, it shows the card uses:
- 20mA when idle (no matter how many extensions)
- 800mA when in full use with Lines 1+2+5 off hook w/4 extensions
- Someone buzzing an extension adds 60mA
In the 800mA case, this means 12 lights in total are lit (3 per extension), 4 relays energized (2 per line), plus power consumed by the hybrid networks for intercom's and the active DTMF circuit.
It uses about +60mA when buzzing an extension.
It uses quite a bit more if a PowerDSINE is using the 12v to actively ring all 4 extensions; I couldn't measure it well because the 1Hz flashing line lamp was throwing off the reading, but the highest reading I saw seemed to add +500mA for ringing.
I don't have one of the Cambridge "black magic" ring gens to test, but I imagine they'd be similar in power consumption. I'll try to get a few for testing.
Of interest, during development, I used the AC ring generator from my old AT&T 551a, which I think puts out 30Hz (I never checked), but when my +12v PowerDSINE modules arrived, which put out 20Hz, gotta say, I prefer the powerDSINE's slower 20hz; a less strident ring. I should probably post a wav file comparing the two rings.
When I make a rev C of the board, I'll include a connector that makes it easier to attach the PowerDSINE ring gen, so that it can tap switched 12v from the board, so the ring gen is "off" when no ringing is present.
Anyway, on to the schematics...
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Schematic - Page 1/3: Covers the relay logic used for the lamps, the A lead handling from the extensions, and the ring and line detect optocouplers, along with the hold logic path through the relays for the hold resistor. (A 160 ohm 1W resistor at the lower right). Small DPDT relays are used for the A lead handling (relay "A") and the line detect (relay "L").
Schematic - Page 2/3: Covers the oscillators for the lamp flash (2 Hz hold "wink") and ring flash (1 Hz during ringing), and the circuit that stretches out the ring detect to keep the ring lamp flashing in between the rings, and finally the ring lamp circuit that mixes the ring stretch and ring oscillator to flash the lamp.
Schematic - Page 3/3: Covers incoming call ring programming for bells, and I added a separate section that allows the buzzers be the audible for incoming calls, allowing one to hear calls without a ring generator. And finally, at the bottom, the DTMF detect circuit used to handle extension buzzing for the intercom.
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Technical questions/feedback welcome.
