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telephone
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bob@coolgroups.com
electronics forum beginner


Joined: 06 May 2006
Posts: 14

PostPosted: Sun Jul 16, 2006 1:52 am    Post subject: telephone Reply with quote

Can someone look at:

http://electronics.howstuffworks.com/telephone5.htm

Do you think this will really work?

Any advice on how to get the 9 volts?

Thanks.
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Alan B
electronics forum Guru Wannabe


Joined: 05 May 2006
Posts: 137

PostPosted: Sun Jul 16, 2006 2:26 am    Post subject: Re: telephone Reply with quote

On 15 Jul 2006 18:52:13 -0700, in message
<1153014733.847998.20510@m73g2000cwd.googlegroups.com>, bob@coolgroups.com
scribed:

Quote:
Can someone look at:

http://electronics.howstuffworks.com/telephone5.htm

Do you think this will really work?

Hope you didn't miss this bit:

"The only thing your little intercom cannot do is ring the phone to tell
the person at the other end to pick up. The "ring" signal is a 90-volt AC
wave at 20 hertz (Hz)."

Quote:
Any advice on how to get the 9 volts?

Because you obviously missed this bit:

"...a 9-volt battery (or some other simple power supply) and a 300-ohm
resistor that you can get for a dollar at Radio Shack."

--

If life seems jolly rotten, there's something you've forgotten,
and that's to laugh and smile and dance and sing!
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Chris
electronics forum Guru


Joined: 24 Mar 2005
Posts: 723

PostPosted: Sun Jul 16, 2006 5:30 am    Post subject: Re: telephone Reply with quote

Alan B wrote:
Quote:
On 15 Jul 2006 18:52:13 -0700, in message
1153014733.847998.20510@m73g2000cwd.googlegroups.com>, bob@coolgroups.com
scribed:

Can someone look at:

http://electronics.howstuffworks.com/telephone5.htm

Do you think this will really work?

Hope you didn't miss this bit:

"The only thing your little intercom cannot do is ring the phone to tell
the person at the other end to pick up. The "ring" signal is a 90-volt AC
wave at 20 hertz (Hz)."

Any advice on how to get the 9 volts?

Because you obviously missed this bit:

"...a 9-volt battery (or some other simple power supply) and a 300-ohm
resistor that you can get for a dollar at Radio Shack."

--

If life seems jolly rotten, there's something you've forgotten,
and that's to laugh and smile and dance and sing!

Yup. And if Radio Shack doesn't have a 300 ohm 1/2 watt resistor, then
270 ohms or 330 ohms will do just fine.

Have fun
Chris
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jasen
electronics forum Guru Wannabe


Joined: 18 Jun 2006
Posts: 204

PostPosted: Sun Jul 16, 2006 5:57 am    Post subject: Re: telephone Reply with quote

On 2006-07-16, bob@coolgroups.com <bob@coolgroups.com> wrote:
Quote:
Can someone look at:

http://electronics.howstuffworks.com/telephone5.htm

Do you think this will really work?

I've done it.

Quote:
Any advice on how to get the 9 volts?

use a 9v battery. if you get tired of paying for new batteries get a plugpack.



Bye.
Jasen
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feebo@nirgendwo
electronics forum beginner


Joined: 17 Jun 2006
Posts: 11

PostPosted: Sun Jul 16, 2006 10:05 am    Post subject: Re: telephone Reply with quote

On 15 Jul 2006 18:52:13 -0700, bob@coolgroups.com wrote:

Quote:
Can someone look at:

http://electronics.howstuffworks.com/telephone5.htm

Do you think this will really work?

Any advice on how to get the 9 volts?

Thanks.

it will.

ummm, try a 9 volt battery

In the pic, the 300 ohm resistor is a non-standard value - if you are
using UK spec phones, go for a 470 ohm - this will extend the battery
life too. Also if you are in the uk, and using modern phones with
electronic ringers, you can make the bell "ring" by rigging a switch
at each end to connect pin 2 & 3 of the standard line jack together.
Press the button to attract the other ends attention then lift the
reciever and wait for them - i.e. it won't work if you have already
lifted the handset.
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Don Bowey
electronics forum Guru


Joined: 25 May 2005
Posts: 451

PostPosted: Sun Jul 16, 2006 3:39 pm    Post subject: Re: telephone Reply with quote

On 7/15/06 6:52 PM, in article
1153014733.847998.20510@m73g2000cwd.googlegroups.com, "bob@coolgroups.com"
<bob@coolgroups.com> wrote:

Quote:
Can someone look at:

http://electronics.howstuffworks.com/telephone5.htm

Do you think this will really work?

Yes

Quote:

Any advice on how to get the 9 volts?

The article told you to use a battery. Do you mean how to get the 9V
*without* a battery? You could use a wallwart.

Quote:

Thanks.


You do not need the resistor. Modern telephones have a DC resistance of
about 430 Ohms, so the two phones in series will limit the current to about
10.4 mA., which is a good value.

Don
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Puckdropper
electronics forum addict


Joined: 13 Sep 2005
Posts: 73

PostPosted: Mon Jul 17, 2006 2:07 am    Post subject: Re: telephone Reply with quote

Don Bowey <dbowey@comcast.net> wrote in
news:C0DFABD9.3A9F0%dbowey@comcast.net:

Quote:

The article told you to use a battery. Do you mean how to get the 9V
*without* a battery? You could use a wallwart.

Obviously the 9V battery is too hard. The OP needs a simple solution
like using 6 AA batteries, or 7.5 NiMH batteries. (Or 8 and a standard
diode.)

*removes tounge from cheek*

Puckdropper
--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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bob@coolgroups.com
electronics forum beginner


Joined: 06 May 2006
Posts: 14

PostPosted: Tue Jul 18, 2006 3:02 am    Post subject: Re: telephone Reply with quote

I wired it, and it works.

Out of curiosity, does it matter if the power is on the red wire or
green wire? The wires appear equal.


Puckdropper wrote:
Quote:
Don Bowey <dbowey@comcast.net> wrote in
news:C0DFABD9.3A9F0%dbowey@comcast.net:


The article told you to use a battery. Do you mean how to get the 9V
*without* a battery? You could use a wallwart.

Obviously the 9V battery is too hard. The OP needs a simple solution
like using 6 AA batteries, or 7.5 NiMH batteries. (Or 8 and a standard
diode.)

*removes tounge from cheek*

Puckdropper
--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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Alan B
electronics forum Guru Wannabe


Joined: 05 May 2006
Posts: 137

PostPosted: Tue Jul 18, 2006 3:16 am    Post subject: Re: telephone Reply with quote

On 17 Jul 2006 20:02:23 -0700, in message
<1153191742.985064.150550@35g2000cwc.googlegroups.com>, bob@coolgroups.com
scribed:

Quote:
I wired it, and it works.

Out of curiosity, does it matter if the power is on the red wire or
green wire? The wires appear equal.

Terminology lesson: red is tip, green is ring. That means, on a bantam
plug, red is the center conductor (the tip) and green is the outer ring of
the plug. Your simple intercom is a current loop, so under normal
circumstances the polarity of the voltage and the direction of current
aren't important. Here's a crude drawing of how it works, ignoring the
hook switch and ringer circuits:

http://www.privateline.com/archive/howteleworks.gif

Just out of curiosity, how are you going to let the person on the other end
know he or she is being summoned to the intercom?

--
Love is like a dying ember
And only memories remain
And through the ages I'll remember
Blue eyes cryin' in the rain
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Puckdropper
electronics forum addict


Joined: 13 Sep 2005
Posts: 73

PostPosted: Tue Jul 18, 2006 8:54 am    Post subject: Re: telephone Reply with quote

Alan B <three-eyes@chernobyl.com> wrote in
news:d3kob2tconvumsf6q5of11169800ff4h27@4ax.com:

Quote:

Just out of curiosity, how are you going to let the person on the
other end know he or she is being summoned to the intercom?


Shouting "Hey! Pick up the phone!" would work. It at least saves you
from having a shouting conversation.

This is an electronics group, though, we can do better. Isn't the ringer
activated by sending a higher voltage on the line?

Puckdropper
--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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jasen
electronics forum Guru Wannabe


Joined: 18 Jun 2006
Posts: 204

PostPosted: Wed Jul 19, 2006 9:15 am    Post subject: Re: telephone Reply with quote

On 2006-07-18, Puckdropper <puckdropper@yahoo.com> wrote:
Quote:
Alan B <three-eyes@chernobyl.com> wrote in
news:d3kob2tconvumsf6q5of11169800ff4h27@4ax.com:


Just out of curiosity, how are you going to let the person on the
other end know he or she is being summoned to the intercom?


Shouting "Hey! Pick up the phone!" would work. It at least saves you
from having a shouting conversation.

This is an electronics group, though, we can do better. Isn't the ringer
activated by sending a higher voltage on the line?

yeah, it should be AC too... 25 to 20 Hz


Bye.
Jasen
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mike7411@gmail.com
electronics forum beginner


Joined: 15 May 2006
Posts: 17

PostPosted: Wed Jul 19, 2006 4:57 pm    Post subject: Re: telephone Reply with quote

Is there an easy way to get this 20 Hz without a frequency generator?

jasen wrote:
Quote:
On 2006-07-18, Puckdropper <puckdropper@yahoo.com> wrote:
Alan B <three-eyes@chernobyl.com> wrote in
news:d3kob2tconvumsf6q5of11169800ff4h27@4ax.com:


Just out of curiosity, how are you going to let the person on the
other end know he or she is being summoned to the intercom?


Shouting "Hey! Pick up the phone!" would work. It at least saves you
from having a shouting conversation.

This is an electronics group, though, we can do better. Isn't the ringer
activated by sending a higher voltage on the line?

yeah, it should be AC too... 25 to 20 Hz


Bye.
Jasen
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Lord Garth
electronics forum Guru


Joined: 24 Mar 2005
Posts: 363

PostPosted: Wed Jul 19, 2006 5:49 pm    Post subject: Re: telephone Reply with quote

<mike7411@gmail.com> wrote in message
news:1153328268.473073.268950@b28g2000cwb.googlegroups.com...
Quote:
Is there an easy way to get this 20 Hz without a frequency generator?

jasen wrote:
On 2006-07-18, Puckdropper <puckdropper@yahoo.com> wrote:
Alan B <three-eyes@chernobyl.com> wrote in
news:d3kob2tconvumsf6q5of11169800ff4h27@4ax.com:


Just out of curiosity, how are you going to let the person on the
other end know he or she is being summoned to the intercom?


Shouting "Hey! Pick up the phone!" would work. It at least saves you
from having a shouting conversation.

This is an electronics group, though, we can do better. Isn't the
ringer
activated by sending a higher voltage on the line?

yeah, it should be AC too... 25 to 20 Hz


Bye.
Jasen


It's not critical, a 555 will do but you will have to boost the output to
the
appropriate voltage.

Bill has a ring generator here:
http://ourworld.compuserve.com/homepages/Bill_Bowden/page11.htm
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Alan B
electronics forum Guru Wannabe


Joined: 05 May 2006
Posts: 137

PostPosted: Fri Jul 21, 2006 3:31 am    Post subject: Re: telephone Reply with quote

On 19 Jul 2006 09:57:48 -0700, in message
<1153328268.473073.268950@b28g2000cwb.googlegroups.com>, mike7411@gmail.com
scribed:

Quote:
Is there an easy way to get this 20 Hz without a frequency generator?

Well, it would be an interesting project to produce 90VAC 20Hz from 120VAC
60 Hz. Food for thought.
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Michael A. Terrell
electronics forum Guru


Joined: 24 Mar 2005
Posts: 2291

PostPosted: Fri Jul 21, 2006 5:01 am    Post subject: Re: telephone Reply with quote

Alan B wrote:
Quote:

On 19 Jul 2006 09:57:48 -0700, in message
1153328268.473073.268950@b28g2000cwb.googlegroups.com>, mike7411@gmail.com
scribed:

Is there an easy way to get this 20 Hz without a frequency generator?

Well, it would be an interesting project to produce 90VAC 20Hz from 120VAC
60 Hz. Food for thought.


Ma bell has done it for decades. The old 1A2 type phone system power
supplies did it with no problems. Junk 1A2 systems can still be found
cheap, or for free. They also supply the filtered DC for the talk
circuit, and power for all of the lamps on the phones.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
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