Telephone interface

bddbbd.b

I am trying to hook up a BS2 to a telephone- I want the phone to dial out based on commands given by the stamp. How does the circuit given in the manual's DTMFout command have to be modified? Do I need an entirely different circuit. Is there another device that would make this problem simpler?
Thanks for the help.

Post Edited (bddbbd.b) : 3/2/2007 2:25:13 AM GMT

stamptrol

The older version of the manual had a circuit for using a matching transformer as the interface device. BUT, it wasn't an approved device to connect to the telephone system.

As for making the problem simpler, get nearly any old modem and let the stamp tell the modem the number to dial.

It gives you an approved interface, some extra control lines like "Dial tone detected", etc and the stamp can easily interface with it on the serial port. Best of all, you can use almost any speed modem and many people will give you a box full of them for a few bucks. Ask around and try to stick with ones that use the Hayes "AT" command set.

Cheers,

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Tom Sisk

http://www.siskconsult.com
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bddbbd.b

Hmm, this is a one-off limited time project so I am not terribly concerned about FCC aproval, though that is certainly good to know. If I used a modem to dial out, what happens when someone picks up the receiver on the phone the stamp is attached to? I need the telephone to behave just like someone had pushed the buttons to dial a number, except the handset is still in the cradle.

stamptrol

The modem will have two telephone jacks. The phone line goes in one and the local telephone in the other. Telephone works as per normal.

For the stamp to dial, it does this:

1. Send the modem the number to dial.
2. Tell the modem to dial the number.
3. What happens at this point will depend a bit on what equipment you have just called.

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Tom Sisk

http://www.siskconsult.com
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quispqix

O.k. here go's, I took the 600 ohm transformers off older modems. and a lot more parts, I love part mining.

Look at the nuts and volts column, Nuts & Volts Volume 1. nv19.zip

www.parallax.com/dl/docs/cols/nv/vol1/code/nv19.zip

the bs2 will dial but if I remember correctly, you need a higher xx2, (All I got are bs2's), for the answering part of the job.
check out nv60 too, but I forgot the volume that was in. also with the proper sequence you can program the bs2 to access your phone messages, (your own (don't make me wait records)) the phone messages are great for determining the pause duration.
And old telephones can be 'circuitry minimized' with the transformer and the proper switches. Also what I found that works the best is an older network block with pushbutton capability (DTMF) you then need 4 switches 2-on 2-off put on the relays you can get from the modems for the handset switches and you can toggle the relays from an output logic transistor driven or sent through an ls04 about 4 times, something to build up the current. but the network blocks are really something beautiful to own.
Also If you think you set up your block correctly and you get no dial-tone (or ring), just reverse the tip and ring wires for the correct polarity. (yes its ac with polarity) (even if that was correct)
Network blocks you can get at the thrift store. they are called telephones. but not that new shtuff, they are actually blocks, not circuit boards. AND REMEMBER how you un wired the block at the screw terminals because there is vertually nothing on the internet about them unless you do a really deep search.
probably because it is a network block it might be fcc approved, but don't quote me. I'll deny everything.

Hotline dialer,... www.vikingelectronics.com/products/view_product.php?pid=160
Not intended to advertise that product!

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Drink Milk!
skype me: quispqix
echolink: 184783 KC0LGV

Post Edited (quispqix) : 3/3/2007 5:26:36 AM GMT

Mike Green

quispqix,
It's much better to use an old modem in that the modem has protective circuitry in it to protect against the ring voltage (maybe as high as 90VAC) and phone line transients (including from lightning). It will also keep you from getting into trouble if your phone suddenly stops working. Sure, you can hack something, but do investigate proper protective networks and build them in.

quispqix

thanks, mike! In the 'circuitry reduced' phohes I hacked. I did leave in the zeners. I assumed their was code to learn in using an older modem, for other than parts. I think the Nuts and volts issues discussed line transients and lightning. Littlefuse has SiBOD Axial telecom fuses for lightning tip and ring circuits. And TVS diodes for transient surges. plus their is alot of application notes put out by the industry (this being telecom and the fuse makers)

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Drink Milk!
skype me: quispqix
echolink: 184783 KC0LGV

Post Edited (quispqix) : 3/3/2007 1:36:07 PM GMT

bddbbd.b

I used the circuit described in the nuts and volts article, and checked it with a phone handset with the red and green wires in series with the phone line's tip and ring: I hear dial tone, and I hear the DTMF tones, but I continue to hear dial tone, and it never connects to the other phone...

So, to clarify what happens if I use a modem is that the stamp sends the number to the modem via serial communication, and tells it to dial through the serial output?... I never use the DTMFout instruction? and what would you estimate the learning curve on the modem is like? It sounds promising, since I know a lot more about programming than circuit design (though little enough of either...). Do you have any suggestions for finding documentation for modem wiring and modem programming?
Thanks for all the help, everyone.

Post Edited (bddbbd.b) : 3/3/2007 10:51:27 PM GMT

quispqix

reverse the tip and ring. just reverese the phone lines the 2 wires. green and red and no I never messed with modems other than in a computer or scavaging for parts. I hope you get it working!

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Drink Milk!
skype me: quispqix
echolink: 184783 KC0LGV

Post Edited (quispqix) : 3/4/2007 3:05:53 AM GMT