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Dear all,
I'm a new member here. Nice to join E_101.
I have a problem. I work in IT field, exactly in O&M server machines.
Since my server often has trouble in application software, I intend
to make an alarm system when trouble occurs. I have made a software
that could play a *.wav file (a 1 minute song) in my PC at the time
when trouble occurs. I wish I could make a hardware (connect from PC
speaker to a phone) that able to call my home phone number at that
time. The concept is: while my PC speaker plays a song, the signal
will generate the hardware to switch the phone's handsfree on. Then,
since my office phone has a "hotline delay" feature, it will
automatically call my home number. And when the song finished, the
handsfree will off again.
Could anybody here help me to describe the circuit of this kind of
hardware? Thanx for your kind attention.
Regards,
Enrico

enrico,

I have made a software
that could play a *.wav file (a 1 minute song) in my PC at the time
when trouble occurs. I wish I could make a hardware (connect from PC
speaker to a phone) that able to call my home phone number at that
time.

Why not create software that dials your home phone, then all you have need is
hardware that switches the phone to hands free mode.

The concept is: while my PC speaker plays a song, the signal
will generate the hardware to switch the phone's handsfree on.

The problem with that is that the speaker creates various sounds so the
hardware would have to distinguish among them. If the computer dials the
phone the dialing program could also send a signal to a port, you might need
a second parallel port to make things simplest. The program would output to
that port, say 'FF' and the hardware then would only need to sense a 1 at one
of the port bits. At the end of the song the software would clear the bits at
that port.

What kind of hardware requirements would the phone require to put it into
hands free mode?

Jim

Thanks Jim,
My purpose is not so complicated. I will use this alarm when I'm not
at my office. And my PC will only 'on' to run this alarm system, so
the speaker will not use to play any other sound except the alarm
song.
Thus my problem is to create hardware that switches the phone to
handsfree mode, generated by electric current/voltage that produced
by my PC soundcard output when it plays the alarm song (I think the
voltage at soundcard output is increase when it produces a sound,
cmiiw). And it should switch off the handsfree when the song finished.
The working concept that I purpose:
1. Trouble occured, software plays a wav song
2. Hardware will switch phone's handsfree on
3. "Hotline delay" feature will automatically call my home number
4. I receive the call at home, then hear the sound of music
5. Song finished, hardware will switch handsfree off
I wish I could have made a simple and cheap hardware that I intend,
because I'm not too expert in electronics. That's all.
Rgds,
Enrico

Thanks Jim,
My purpose is not so complicated. I will use this alarm when I'm not
at my office. And my PC will only 'on' to run this alarm system, so
the speaker will not use to play any other sound except the alarm
song.
Thus my problem is to create hardware that switches the phone to
handsfree mode, generated by electric current/voltage that produced
by my PC soundcard output when it plays the alarm song (I think the
voltage at soundcard output is increase when it produces a sound,
cmiiw). And it should switch off the handsfree when the song finished.
The working concept that I purpose:
1. Trouble occured, software plays a wav song
2. Hardware will switch phone's handsfree on
3. "Hotline delay" feature will automatically call my home number
4. I receive the call at home, then hear the sound of music
5. Song finished, hardware will switch handsfree off
I wish I could have made a simple and cheap hardware that I intend,
because I'm not too expert in electronics. That's all.
Rgds,
Enrico

enrico,

And my PC will only 'on' to run this alarm system, so
the speaker will not use to play any other sound

OK, so the speaker sound will switch the phone to 'hands free' and will never
output any other sound. Really simple, the circuit is call a 'vox', voice
activated circuit. The simplest approach is to connect the circuit to the
speaker which could actually be mounted inside the speaker. Connect a
rectifier diode and an electrolytic capacitor in series across the speaker.
Polarity considerations later. This circuit will produce as small DC voltage
when there is sound coming from the speaker. You might also need a series
resistor to reduce the distortion that the diode might cause, a 1 thousand
ohm value should be about right. The control signal will be obtained across
the capacitor. The disadvantage here is that the voltage level of this
control signal will vary with the sound volume.

Now what you do with the resulting DC across the capacitor depends on what
kind of control the phone uses for hands free operation. And I'm not clear
what device does the auto dial of your home phone.

Diode and capacitor polarities. The diode cathode, with the little silver
stripe must go to the capacitor + terminal. So the sequence might go like
this. Connect a 1 thousand ohm resistor to one speaker terminal, doesn't
matter which one. Connect the Diode anode (no silver stripe) to the resistor,
then the diode cathode (silver stripe) goes to the + side of the 10
microfarad capacitor (symbol on cap looks like uF). Negative side of
capacitor goes to other speaker terminal.

2. Hardware will switch phone's handsfree on

I can't tell you more until I know whether the phone has provision for
external control of the hands free.

3. "Hotline delay" feature will automatically call my home

Is this entirely a function of the phone, i.e. it calls your home when it
goes to 'hands free'?

4. I receive the call at home, then hear the sound of music

This is the reason for the 'hands free mode', ok that makes sense.

5. Song finished, hardware will switch handsfree off

When the sound quits the capacitor will discharge and there will be no more
control voltage.

Here's an alternative. Most computers have the ability to dial telephones
through the computer modem. They might also have the ability to send sound to
that dialed phone. If the music had a known length the time to 'hang up'
could just be timed to that length.

More after you give more info.

Jim

Enrico,

If you want the sound to be played over the phone you'll need to connect it to the device that operates the phone.

I would use your PC's modem for phone control - don't reinvent the wheel if you don't have to.

Your error routine would go something like this:

1) Take the phone off hook. Either send the ATH1 command and wait, or you could just dial the number with ATDT[*70,]xxx-xxxx.)

2) Wait for connection (use a loop here to redial if no connection is made). The modem will send a result back to the port, which you can read, to signal a connection. This involves setting the result mode with the ATX command (ATX4 will report all progress codes: BUSY, NO ANSWER, etc.).

3) Play sound. Add a jack to the speaker to connect its output to the phone line. Use diodes to prevent the phone line voltage from interfering or damaging your speaker.

4) Hang up phone. (ATH0)

-Mike



enrico@...:

I'm a new member here. Nice to join E_101.
I have a problem. I work in IT field, exactly in O&M server machines.
Since my server often has trouble in application software, I intend
to make an alarm system when trouble occurs. I have made a software
that could play a *.wav file (a 1 minute song) in my PC at the time
when trouble occurs. I wish I could make a hardware (connect from PC
speaker to a phone) that able to call my home phone number at that
time. The concept is: while my PC speaker plays a song, the signal
will generate the hardware to switch the phone's handsfree on. Then,
since my office phone has a "hotline delay" feature, it will
automatically call my home number. And when the song finished, the
handsfree will off again.
Could anybody here help me to describe the circuit of this kind of
hardware? Thanx for your kind attention.
Regards,
Enrico

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Thanks again, Jim
So the circuit: D
+ -----/\/\/\--->|------
R=1K + - |+
Speaker = C=10uF
|-
- ----------------------
I've a little comprehension about this circuit: if the current
occured, it will by-pass the diode (a kind like IN4001?) to deliver
current through (but what R is for? Won't it decrease voltage level
that occured from speaker? And if the output signal from speaker is
small, is it enough to make diode pass the current? I thought diode
has a 0,7V threshold). C will do for storage the signal.

Now what you do with the resulting DC across the capacitor

depends on what kind of control the phone uses for hands free
operation. And I'm not clear what device does the auto dial of your
home phone.

Auto dial will do by a feature from our Telcomm (Hotline delay), i.e.
when we pick up the phone and hang it for 5 seconds (not dial
anything), it will always automatically call a number that we want.

I can't tell you more until I know whether the phone has

provision for external control of the hands free.

I've seen inside the phone circuit. It has not any provision for
external control. The handsfree switch is a button, it's like our TV
remote control button, I called it "touch switch". We press it once
to turn on, once again it will off, there's no difference switch
position between on/off. I hope you understand what I mean.

Here's an alternative. Most computers have the ability to dial

telephones through the computer modem...

I don't have any modems, I think it's a good solution (just like d
nixon advice) but expensive, beside, I don't understand about AT
command.

Rgds,
Enrico

enrico,

So the circuit: D
+ -----/\/\/\--->|------
R=1K + - |+
Speaker = C=10uF
|-
- ----------------------
I've a little comprehension about this circuit: if the current
occured, it will by-pass the diode (a kind like IN4001?) to deliver
current through (but what R is for?

When I suggested the resistor I was thinking about the speaker having to
handle other sound, which might be distorted with the diode connected. The
resistor might cause a slight delay in the charge on the capacitor. The
effect would depend on what voltage level was required by the device being
controlled.

And if the output signal from speaker is
small, is it enough to make diode pass the current?

This would take some experimentation. The resistor value
could be reduced if necessary, perhaps even removed.

I thought diode has a 0.7V threshold).

I think the output voltage should be greater than 1V.

C will do for storage the signal.

Auto dial will do by a feature from our Telcomm (Hotline delay), i.e.
when we pick up the phone and hang it for 5 seconds (not dial
anything), it will always automatically call a number that we want.

If you have to do this manually, i.e. no kind of plug in remote control, I
don't see how this feature can be use.

Here's an alternative. Most computers have the ability to dial

telephones through the computer modem...

I don't have any modems, I think it's a good solution (just like d
nixon advice) but expensive, beside, I don't understand about AT
command.

AT commands are not difficult, but it doesn't matter if you can't afford a
modem.

Jim

Okay, Jim. I think I must go on anyway.

When I suggested the resistor I was thinking about the speaker

having to handle other sound, which might be distorted with the diode
connected. The resistor might cause a slight delay in the charge on
the capacitor. The effect would depend on what voltage level was
required by the device being controlled.
This would take some experimentation. The resistor value could be
reduced if necessary, perhaps even removed.

I thought 1K is too much, how if we didn't use any R?

I thought diode has a 0.7V threshold).

I think the output voltage should be greater than 1V.

Do you know how many voltage is the output of any soundcard (built in
amplification)? I hope it's greater than 1V. Because now I use a
passive speaker. If it necessary, I will use active speaker.

If you have to do this manually, i.e. no kind of plug in remote

control, I don't see how this feature can be use.

Doesn't mean I have to give up on this, right Jim? I hope I could
make a manipulation by soldering a cable from 'vox' hardware to the
phone circuit (PCB). I've seen the phone PCB and found 2 track that
work to the handsfree button switch. It would be easier for me if the
switch is like on/off model (like our house lamp switches), but
unfortunately it's a touch button. Can you tell me Jim how
the "touch" button works?

AT commands are not difficult, but it doesn't matter if you can't

afford a modem.

I will try this alternative way if I can't go on with the hardware
later.

Regards,
Enrico

enrico,

I thought 1K is too much, how if we didn't use any R?

That's an option, and if you don't use the speakers for sound the diode won't
matter. That's up to you.

If it necessary, I will use active speaker.

That certainly would give you a better signal. I haven't seen
a passive speaker in a long time. Even the little cheap ones
are powered now.

If you have to do this manually, i.e. no kind of plug in remote

control, I don't see how this feature can be use.

Doesn't mean I have to give up on this, right Jim? I hope I could
make a manipulation by soldering a cable from 'vox' hardware to the
phone circuit (PCB).

Be careful that you don't damage it so it won't do it's primary function.
This doesn't sound like a cheap phone. :-)

Can you tell me Jim how the "touch" button works?

That depends on what you mean by a 'touch button'. I'm
assuming you mean that you touch it once and it goes on,
again and it goes off. That would mean that a momentary
short across the switch terminals toggles the phone
circuit on or off, again and it goes the other way.
It's not difficult to produce a pulsed short circuit,
that closes for a second to turn on the circuit and
again to turn it off. What to use depends on the
kind of signal the sound detector produces (coming
from the speaker).

Jim