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Req circuit to record from phone line (UK)

L

Lem

Jan 1, 1970
0
I'm in the UK. I want to record my landline phone calls.

I once made a crude device which had a transformer (don't know its
spec). A pair of wires from one side of the transformer went into
the telephone wall socket and a pair of wires on the other side of
the transformer went to a jack plug which goes into my recorder.
There's a potentiometer adjusts the output level.

It kind of works but not very well and I get too much hum.

What would be a proper circuit to follow?

Even better, is there a non-expensive recording adapter I can buy
in the UK which plugs into the phone wall socket?










This is posted to uk.telecom and to some elctronics groups.
 
P

Phil Allison

Jan 1, 1970
0
"Lem"
I'm in the UK. I want to record my landline phone calls.

** With WHAT as the recorder ?

I once made a crude device which had a transformer (don't know its
spec). A pair of wires from one side of the transformer went into
the telephone wall socket and a pair of wires on the other side of
the transformer went to a jack plug which goes into my recorder.
There's a potentiometer adjusts the output level.

It kind of works but not very well and I get too much hum.

What would be a proper circuit to follow?


** Get a small (about 50 mm square) 600 ohm to 600 ohm transformer rated
for telephone line use.

On the line side, add a 0.22uF, 100volt cap and series resistor of 10
kohms, also fit a 4.7 kohm across the winding.

On the output side, use a pot to match the signal to the mic input of a
cassette recorder - you can test by making a dummy phone call on the same
line.

Keep the transformer away from sources of AC hum.



.......... Phil
 
T

Terry

Jan 1, 1970
0
I'm in the UK. I want to record my landline phone calls.

I once made a crude device which had a transformer (don't know its
spec). A pair of wires from one side of the transformer went into
the telephone wall socket and a pair of wires on the other side of
the transformer went to a jack plug which goes into my recorder.
There's a potentiometer adjusts the output level.

It kind of works but not very well and I get too much hum.

What would be a proper circuit to follow?

Even better, is there a non-expensive recording adapter I can buy
in the UK which plugs into the phone wall socket?

Try this
http://www.voicecallcentral.com/
-
 
I

Ian Bell

Jan 1, 1970
0
Lem said:
I'm in the UK. I want to record my landline phone calls.

I once made a crude device which had a transformer (don't know its
spec). A pair of wires from one side of the transformer went into
the telephone wall socket and a pair of wires on the other side of
the transformer went to a jack plug which goes into my recorder.
There's a potentiometer adjusts the output level.

It kind of works but not very well and I get too much hum.

What would be a proper circuit to follow?

Even better, is there a non-expensive recording adapter I can buy
in the UK which plugs into the phone wall socket?

Check out this months Elektor magazine, there is a design for one in there.

Ian
 
M

Martin²

Jan 1, 1970
0
Atachment is available at your local Maplin store or online.
Regards,
Martin
 
W

Walter Harley

Jan 1, 1970
0
Lem said:
I'm in the UK. I want to record my landline phone calls. [...]

A search term that might help you is "phone hybrid". That's what we call
these audio-to-telephone interfaces in the broadcast industry.
 
J

Jonathan Etheridge

Jan 1, 1970
0
Walter Harley said:
Lem said:
I'm in the UK. I want to record my landline phone calls. [...]

A search term that might help you is "phone hybrid". That's what we call
these audio-to-telephone interfaces in the broadcast industry.
If you want to go down this route have a look at

http://www.vtx.co.uk/

They have loads of products (but not 'inexpensive')

I've used several of the JK Audio 'THAT' range (THAT-1 and THAT-2).

The THAT-2 (http://www.vtx.co.uk/audio/that2.htm ) pretty good unless you
want broadcast quality kit. I think it cost me about £120 tho'

Has a phono and XLR in and out

Jonathan
 
K

Ken S

Jan 1, 1970
0
Use phone input circuit in old computer dial up modem.
KS
Walter Harley said:
Lem said:
I'm in the UK. I want to record my landline phone calls. [...]

A search term that might help you is "phone hybrid". That's what we call
these audio-to-telephone interfaces in the broadcast industry.
If you want to go down this route have a look at

http://www.vtx.co.uk/

They have loads of products (but not 'inexpensive')

I've used several of the JK Audio 'THAT' range (THAT-1 and THAT-2).

The THAT-2 (http://www.vtx.co.uk/audio/that2.htm ) pretty good unless you
want broadcast quality kit. I think it cost me about £120 tho'

Has a phono and XLR in and out

Jonathan
 
L

Lem

Jan 1, 1970
0
How do you use the input circutry of an old external model to let me
record phone calls?


Use phone input circuit in old computer dial up modem.
KS
Walter Harley said:
I'm in the UK. I want to record my landline phone calls.
[...]
If you want to go down this route have a look at
http://www.vtx.co.uk/

They have loads of products (but not 'inexpensive')
I've used several of the JK Audio 'THAT' range (THAT-1 and
THAT-2).

The THAT-2 (http://www.vtx.co.uk/audio/that2.htm) pretty good
unless you want broadcast quality kit. I think it cost me about
œ120 tho'

Has a phono and XLR in and out

Jonathan
 
L

Lem

Jan 1, 1970
0
"Lem"



Get a small (about 50 mm square) 600 ohm to 600 ohm
transformer rated for telephone line use.

On the line side, add a 0.22uF, 100volt cap and series
resistor of 10 kohms, also fit a 4.7 kohm across the winding.

On the output side, use a pot to match the signal to the mic
input of a cassette recorder - you can test by making a dummy
phone call on the same line.

Keep the transformer away from sources of AC hum.

Hum is my chief problem now. Is there an alternative circuit
(nothing too complicated please!) which is less likely to pick up
hum.

I will be using this near my PC and all the extra wires and
devices you might expect.
 
R

Ruth

Jan 1, 1970
0
Christopher said:
Hello Lem,

This is what you want from Maplins Electronics in UK

http://www.maplin.co.uk/module.aspx...one Recording Devices&ModuleNo=30350&doy=21m3

Enjoy,

* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com

For recording from a telephone, you need low background noise and good
balance between the near and far party. Check out
http://www.retellrecorders.com/recording/machine/650.htm which sounds
like hi-fi even on an ordinary telephone call. There is a description at
http://www.retellrecorders.com/help/connectors.htm with sample files
that you can listen to.
RuthWest
 
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