larry@uunet.uu.net> (08/24/90)
In article <11088@accuvax.nwu.edu> atn@cory.berkeley.edu (Alan Nishioka) writes: > I am trying to build a box for my five line key system phone. I want > it to flash the lights and do automatic hold. > The system I was going to time has been dismantled and replaced with > Panasonic phones with LEDs so you can't tell which line is ringing... I would suggest that you look around for a used key service unit (KSU) with 400-type line cards, which will perform all of the functions you desire. With the extensive proliferation of electronic key telephone systems and "mini" PABX's, such used KSU's often sell for very little money - especially at say, an amateur radio flea market. Design of a 1A2 key system to work with your telephones is not a trivial effort. It's not that difficult, either, but you will spend some time doing it. If you are determined to build it from scratch, I would suggest a "non-traditional" approach. Use a microprocessor with I/O expander for all logic and timing functions. Detect ringing and loop current using optoisolators. Drive the lamps with ten volts DC switched by suitable current drivers. Sense the A-lead ground closures preferably with optoisolators. Use a reed relay to place a 300 ohm hold resistor across the telephone line. In summary, your microprocessor would have five ringing detector inputs, five loop current detector inputs, five A-lead inputs, five lamp outputs, five hold relay outputs, and one common audible relay signal output. Everything else is software. :-) The lamp signals and interrupted common audible signal sequence would be generated under software control. Yet another alternative would be to obtain just the 400-type line cards, make your own card cage, and build a power supply and interrupter circuit yourself. All you need is -24 volts DC for the 400-type line card control power and ten volts AC for lamps (do not substitute DC for AC on the ten volt lamp circuit with newer 400-type line cards since they use triacs or SCR's for lamp control instead of relay contacts). The standard KSU interrupter operates from the ten volt AC supply. You will also need 18 volts AC or 20/30 Hz ringing for common audible signals, depending upon whether you use buzzers or ringers. > Does anyone have the light flashing cadences? (frequency and duty > cycle). Lamp flash for incoming calls is interrupted at 60 IPM with a 50% on-duty cycle (i.e., 500 ms on, 500 ms off). Lamp wink for hold is 120 IPM with an 80% on-duty cycle (i.e., 400 ms on, 100 ms off). Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" {boulder||decvax||rutgers||watmath}!acsu.buffalo.edu!kitty!larry VOICE: 716/688-1231 || FAX: 716/741-9635 {utzoo||uunet}!/ \aerion!larry
William.Degnan@f39.n382.z1.fidonet.org (William Degnan) (08/25/90)
In article <11088@accuvax.nwu.edu> atn@cory.berkeley.edu (Alan Nishioka) writes: > I am trying to build a box for my five line key system phone. > I want it to flash the lights and do automatic hold. > The system I was going to time has been dismantled and replaced > with Panasonic phones with LEDs so you can't tell which line is > ringing... I picked up a 1A2 with four line cards for five bucks. A few other folks _gave_ me some key telephone sets. There is little commercial value. You probably would use more than $5 worth of gas picking up the parts. Why not see what you can find gathering dust someplace? Regards, Disclaimer: Contents do not constitute "advice" unless we are on the clock. William Degnan | wdegnan@mcimail.com Communications Network Solutions | !wdegnan@at&tmail.com -Independent Consultants | William.Degnan@telemail.com in Telecommunications | UUCP: ...!natinst!tqc!39!William.Degnan P.O. Drawer 9530 | ARPA: William.Degnan@f39.n382.z1.FidoNet.Org Austin, TX 78766-9530 | Voice +1 512 323 9383
Beach@cup.portal.com (08/25/90)
On the subject of actually BUILDING a 1a2 ANYTHING -- After talking recently to a few phone system people in the SF BAY area, I would just go out any BUY 1A2 stuff if I needed it as these guys will sell it for practcally nothing. Examples $10 for five line phone ... Maybe $2 for a 400 line card. $50 would probably get you a complete system with phones if you call the right place. Since not many businesses WANT 1A2 stuff, and it gets traded in all the time, the trade in stuff is cheap and easy to come by. Do some calling in your area. In this case I think it is cheaper to buy it than build it. Steve Warner fremont, CA, USA, etc
john@bovine.ati.com (John Higdon) (08/28/90)
Beach@cup.portal.com writes: > $50 would probably get you a complete system with phones if you call > the right place. Since not many businesses WANT 1A2 stuff, and it > gets traded in all the time, the trade in stuff is cheap and easy to > come by. Jeez, anyone who shows up at my doorstep can have, absolutely free, any and all 1A2 stuff they can find in my garage. There is at least one KSU with an assortment of standard and specialized line cards, at least five telephones in pretty good shape, and an assortment of other 1A2-style garbage. > Do some calling in your area. In this case I think it is cheaper > to buy it than build it. With the advent of cheap electronic key equipment (that doesn't require the bulky 25 pair cable), someone's elevator would have to stop short of the top floor to want to mess around with 1A2 anymore. My business associate, the most die-hard of 1A2 enthusiasts, has finally given up the cause. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
johnb@jbx.com (John Boudreaux) (08/29/90)
I've been blessed(cursed) with hooking up some 1A2 stuff. Anyone know where I can get the wiring layout etc for it? I thought I had it all but ... It works, but no lights and no interupter and hold hangs up the line? John Boudreaux INTERNET: johnb@jbx.com JBX UUCP: ...!uunet!jbx!johnb *Disclaimer* - I Don't Care What Anyone Thinks of My Views