Components Needed to Build Stand-Alone Touch-Tone Keypad

[Scotophor]

I'll start with some background: I have installed my Northern Electric NE-500 phone in the computer room where previously there was no phone, and that of course resulted in complaints from my mother that when she received automated calls she couldn't "press 1" or "press 2" to respond, though the phone is otherwise working and can dial out just fine. So, I bought a pocket touch-tone dialer and put it beside the phone. I still get complaints, because Mom can't deal with picking it up, turning it on and holding it flush against the transmitter cap while pressing the buttons.

So, since somewhere around here I have a touchtone keypad unit pulled from a phone long ago, I was wondering what it would take to make it functional and "tap in" to the NE-500 phone without altering that phone. Assume for now that my keypad is a common unit from a late-issue WE-2500 -- I'll dig it out later and post what it really is. If I could find a "piggyback" 4-prong plug with socket to make my project box essentially another extension on the line, would I need to add a network, condenser, bridge rectifier in case of reversed polarity, or other component(s)? Would this project not be feasible due to lack of connections to the phone's hookswitch, meaning that the keypad box will always be across the phone line even when the phone is on-hook?

EDIT: My TT keypad is labeled, "DIGITAL TEL-TOUCH DIAL" and "DY-1-0" on the circuit board and ink-stamped, "42 OPG 9-84-19" on the front. I assume it has some relation to an ITT model #42. See Reply #14 below for more.

[paul-f]

Check this out:

Wiring A Touch Tone Pad To Any Antique Telephone

By Stan Schreier  
http://atcaonline.com/ttpad.html

[Scotophor]

Thanks, Paul!

OK, so from that it looks like I can't do it exactly like I wanted to... apparently the TT pad has to go in series with the voice circuit, but beyond the ringer?

So if I didn't want to mess with the phone at all, I would have to come up with some way to isolate the TT pad from seeing ringing voltage.

What about placing the TT pad in series with L1, and putting a reverse-series pair of 5.1-volt zener diodes, in parallel with the TT pad? That way, the only trick wiring would have to be inside my "piggyback" plug, and the TT pad would never see more than about 5.8 volts, though the ringing voltage to the phone might be reduced by that amount.

[Phonesrfun]

I don't understamd why putting a phone in a room that previously had no phone at all would result in a problem.  That being said, why not just have two phones in the same room?  One rotary and the other DTMF?

[paul-f]

Bill, I was about to post the same question.  My solution is to put a modular splitter at the wall and plug in a second phone.  There's no shortage of phones here.

Another approach is to use the Bell System approved way of adding an adjunct dial to a set.  Details are found in 501-164-130 I12.  There are four issues in the TCI Library.  The latest one is here:

http://www.telephonecollectors.info/index.php/document-repository/doc_details/9024-501-164-130-i12

[stub]

Scotophor,
                Here's how I did mine to work on every phone I have. Reply 65 thru 71. Build keypad and put it in series with L 2 green .   stub         http://www.classicrotaryphones.com/forum/index.php?topic=458.msg73211#msg73211

paul-f,
               Thanks!!!!  stub

[paul-f]

Thanks, Stub.

This would make a good "how to" tutorial in a separate topic with a title that would turn up in a search.  You might integrate some of the info on the dial pad from the external site.


BTW, if you click on the blue message title for reply 65, you'll get a direct URL in your browser window that can be pasted in a message, so the rest of us go directly to the message you wan tus to see.

You can also use the "Insert Hyperlink" icon (second from left in the second row of icons when composing a post) instead of tinyURL.

http://www.classicrotaryphones.com/forum/index.php?topic=458.msg73211#msg73211

It shows us where our click is taking us, and (I believe) eliminates the previous line wrapping problem that led us to use tinyURL or other services in the past.

[Mr. Bones]

Tidier, still:

<twiddle>
Stub's Stand-Alone Touch-Tone Keypad tutorial
or
Stub's stand-alone DTMF keypad tutorial
etc., whatever is best for you.
</twiddle>

Still shows the URL in my screen's lower left corner when I hover the cursor, at least in XP.

Hope it helps, Best regards!

[Scotophor]

I don't understamd why putting a phone in a room that previously had no phone at all would result in a problem.

Someone living here is apparently selectively unfamiliar with the "gift horse" adage...

That being said, why not just have two phones in the same room?  One rotary and the other DTMF?

Only the largest room here is "allowed" more than one land-line phone, and that's the living room, which has a touch-tone Trimline style phone (beige BellSouth TP201L-10) and a relatively recent cordless digital answerphone.

[Scotophor]

Here's how I did mine to work on every phone I have. Reply 65 thru 71. Build keypad and put it in series with L 2 green. http://www.classicrotaryphones.com/forum/index.php?topic=458.msg73211#msg73211

OK, so I can wire it like I suggested above, but leave out the zener diodes, and ringing voltage won't hurt the TT pad in that configuration, even with an older ringer such as a 302? That sure simplifies things from all of those "adjunct dial" BSP's! I don't think I saw one of them with less than 5 wires to the adjunct dial, and every one of them requires modifying the phone's internal wiring.

Thanks, Stub!

[TelePlay]

This would make a good "how to" tutorial in a separate topic with a title that would turn up in a search.

Since I've personally spent a lot of frustrating time searching the forum for those two links in the past year, this topic does indeed have good information so I made it a sticky topic on this board.

Also, a search for "touch tone keypad" does find this topic along with only 39 others so it is "searchable" with reasonable results if one forgets which board this is in. This should help for now, at least until a better "fix" is determined/decided by others.


xzzx-stand alone touch tone dialing pad-xzzx

[poplar1]

Scotophor,
                Here's how I did mine to work on every phone I have. Reply 65 thru 71. Build keypad and put it in series with L 2 green .   stub         http://www.classicrotaryphones.com/forum/index.php?topic=458.msg73211#msg73211

paul-f,
               Thanks!!!!  stub

Stub, how did you reduce the 8 wires on a Touch-Tone dial to just 2? I didn't see the wiring in reply 65-71.

[poplar1]

AT&T stores sold a 4-number dialer. The Touch-Tone pad inside is for programming the 4 speed-dial buttons, but can also be used for dialing out.

There is a modular jack on the base for "line," and a modular-ended pigtail for the phone. So if you are connecting it to an older phone that doesn't have a built-in modular line jack, you would have to use a coupler to connect the pigtail to the phone. I reckon they decided not to have two modular jacks on the unit so that the customer wouldn't inadvertently swap input and output


.http://www.oldphoneworks.com/four-number-dialer.html

[stub]

poplar1 ,
           Read this article  " Wiring A Touch Tone Pad To Any Antique Telephone by Stan Schreier " and it will tell you which wires you can cut off. When you get the pad wired just hook it up in series with the green line in wire like mine in the pics and your good to go. Hope this helps.  stub                     

http://atcaonline.com/ttpad.html
( dead link 01-07-22 )

[Scotophor]

I finally managed to dig out my TouchTone keypad. From the ink stamp on the front, "42 OPG 9-84-19" I assume it's a model #42, but it doesn't have any familiar branding on it. At the top of the foil side of the PCB it has "DIGITAL TEL-TOUCH DIAL" and "DY-1-0". Unlike the ITT #42 which Stan Schreier calls his "favorite" on the ATCA page, mine's circuit board is larger and only has one female spade connector (hidden behind a varistor in the component side photo, and identified as "L2" on the foil side), and a much larger quartz crystal. However, mine and all three on Stan's page seem to share the same wire colors, so I will also assume that mine is functionally identical, and can be wired per his instructions for the Premier brand and WE #72 keypads using the green "F" wire for the L1 connection.

Interestingly, my keypad has a metal clip-on "option" jumper near one corner of the circuit board, which none of Stan's appear to have. On the component side, lower right corner in the photo, the jumper is near an ink-stamped "F" marking. On the foil side, lower left corner in the photo, you can see that in its current position this jumper does nothing, but if it were moved upward about 3/8 inch, it would connect two contact pads. Does anyone know what this "option" setting does?