Schematic of a DTMF phone dialer

Hi,

I need DTMF phone dialer which will be activeted when home alarm is trigered. Can somebody send me schemes or URL link ?

wbr

Ziko

xtall para cm8870

Depending on the alarm system there may be some possibiities with minimum hardware tinkering:

1) Find a ready made dialer from some "junkshop". They have been used for years for the very same purpose, and old alarm systems are dumped all the time.

2) If you have a PC as a part of the system, you may use a modem card to dial.

3) You might get a "feature-phone" with dial memories and one-touch dial button(s) and make that phone to dial for you. Reed relays or other sensitive relays might be the easiest way to "push the buttons"

And, of course, there are dialer chip makers which give out application notes how to construct a dialer. But tinkering one is a lot of work Also, handling a phone line loop is not very difficult, but to make one legal and reliable circuit is not easy without experience or copying others' tested designs.

Try also Google search for "phone dialer dtmf schematics" or similar....

Good luck,
Ted

phone dialer dtmf

hi .. all mentioned before are excelent, if you can not use those ... use old cheap modem and some mcu on rs232 to send atd command to this ... looks cheaper then build it from scratch ... at least trafos and line eq is there

regards

cancel

dtmf phone

Please use ICs: CM8870 ans LM567.
I have made a board. It work very well.

smallest dtmf phone

lol

what you need is a relay activate the line a selector to select the digits normaly on the toy and or gate {for a clock 1khz to gate the selector and matrix} and some diodes one for the phone line to modulate it the others for the diode matrix

you also need a cheep kids telephone
it hasa dtmf chip in it and 8 handy data lines
gives nice clear dtmf and works as a speed dialer when connected to dial a preset number
made by a diode matrix

this is one solution using an n code
to set the number to dial

these phone things are so cheep and cheerfull you even find then dangle from keyrings in the local newsagent

for less the 1euro 50% cheeper than a chip runs from 1.5 or 3 v ua

dtmf dialer

Hi, this talk seems realy easy.

But i got a real trouble:
I use a cell phone to connect an AVL to the central.
All ok when gprs is working, then if out of range i switch to
plain data, but sometimes i just have plain AMPS so it must
go via DTMF...
Trouble is that when i connect voice mode, giving a second dial
simply hangs up my connection.
Like when you get into a bank, press 1 for balance, 2 for.. 9 for operator..
if i give an ATD1# per example, line gets disconnected.
On old TDMA models all worked fine...
Any hints??
Best

PadsPCB

picbasic dtmf phone dialer

Use a HT9200A from Holtek it's a dtmf dialer chip.
or CMX605 from CML, it's a function generator, and dtmf dialer.

what is the function of cm8870?

Use

20MHZ xtall + PIC + Dtmfout(picbasic)

lm567+dtmf

I use ht9200 for generated dtmf and cm8870 for dtmf decoder.