TAP-1
Telephone Audio + Power Interface
User Guide
JK Audio
Introduction
TAP-1 lets you attach an analog telephone to your
consumer or laboratory grade audio equipment or PC sound
card using standard RCA audio input and output jacks.
There are three jacks on the front of TAP-1. The RJ-11
"phone" jack is the electrical equivilent to the wall jack that
you would typically plug your telephone into. Technically
speaking, TAP-1 provides up to 70 milliamps of -48 volts DC
to power your telephone and then separates the telephone
audio signal into transmit and receive voice paths. This is
similar in function to the line card on a telephone company
central office switching system. The RCA jacks provide high
quality transmit and receive voice paths to your audio
equipment.
The rear panel of the TAP-1 has three adjustments which
are accessible with a small, flat blade screwdriver. The input
level adjustment controls the volume of the signal going
through TAP-1 and into the phone. The output level adjusts
the volume from the phone to your audio equipment. The
null adjustment is used to fine tune the transmit / receive
separation between the telephone and the TAP-1. This is
commonly referred to as trans-hybrid loss or echo return
loss.
Connection
1) Connect a telephone to the front panel RJ-11 jack. DO
NOT CONNECT THIS JACK TO A TELEPHONE LINE.
2) Connect a signal source (CD player, D/A converter,
signal generator...) to the input jack.
3) Connect the TAP-1 output jack to the input of your
equipment (amplifier line input, tape recorder input,
oscilloscope...).
4) Plug in the supplied AC adaptor and apply power.
5) Adjust the line input and line output volume controls to
suit your application.
2
Applications
A single TAP-1 can be used in applications such as:
+ Phone testing and evaluation,
+ Training ASR algorithms for phone line use,
+ Simulating phone based services without actual
connection to a phone line.
Input__ __Output
Computer simulating
a central office
Service Simulator Example
3
Applications
Two TAP-1s can be used in applications such as:
+ Hardwired, telephone based intercom
+ Getting real "telephone bandwidth" recordings from
TV studio telephones.
Input__ __Output
TV Studio Example
Input__ __Output
Tape recorder
or console
4
Applications
A single TAP-1 can also be used for internet telephone use
to give you the feel of a real telephone while talking over the
net. If you use a cordless telephone you can walk around
your office or home without being tied to your computer.
Input__ __Output
Computer connected
to the internet
Internet Telephone Example
5
Sound
card
Hybrid Null Adjust (optional)
The null adjustment allows you to manually optimize the
relationship between the hybrid in your telephone and the
hybrid in the TAP-1. In most applications, this can be left at
the factory setting, or set once and then left alone. If
however you are concerned with transmit / receive isolation
then you should follow this procedure:
1) With a telephone connected and in the off-hook
position, play a sine wave, noise source, or other
suitable signal into the TAP-1 line input jack. Be sure to
cover the microphone of the handset to prevent the
acoustical signal from traveling from the receiver to the
microphone.
2) Observe the signal on the output jack of the TAP-1
using a meter, oscilloscope, or amplifier and speaker.
3) Adjust the null control to find the minimum (the point
where the signal bottoms out, or is reduced to near
zero). The null adjust is a ten-turn control. Keep turning
in one direction or the other to find the null or until you
hear or feel a click. The click means you are at the end
of travel and you must reverse directions.
6
Features
Electrical:
RJ-11
AC Impedance: 510 ohms
DC series resistance: 480 ohms
DC Voltage: -48VDC (open circuit)
DC Current Max: 70 mA (short circuit)
Trans-Hybrid Loss: > 50 dB at 1 kHz
Hybrid Null Adjust: Rear panel recessed control
Input
Connector: Gold plated RCA jack
Impedance: 600 ohms
Level: Rear panel recessed control
Bandwidth: 60 Hz - 15 kHz (±3 dB)
120 Hz - 8 kHz (±1 dB)
Output
Connector: Gold plated RCA jack
Impedance: 600 ohms
Level: Rear panel recessed control
Bandwidth: 180 Hz - 12 kHz (± 3 dB)
300 Hz - 6 kHz (± 1 dB)
Physical:
Housing: ABS plastic
Size: 1.6" high x 5.1" wide x 5.2" deep
Weight: 1 pound
Power: 18 VAC, 160 mA
120 VAC, UL approved transformer
7
Warranty
The Model TAP-1 Interface is covered by a 2 year
warranty to be free from defective workmanship and
materials. In the event that the TAP-1 needs repair, you
must call us to get an authorization, and then carefully
pack and ship it to us. You will pay for shipping to us and
we will pay for return back to you, UPS ground. No free
repairs will be made if the defect was caused by misuse,
weather conditions, or other cause, except for defective
workmanship or materials. THERE ARE NO EXPRESSED
OR IMPLIED WARRANTIES WHICH EXTEND BEYOND
THE WARRANTY HERE MADE.
06/06
JK Audio,Inc. 1311 E 6th Street, Sandwich, IL 60548 USA
Voice: (815) 786-2929 Toll Free: 800-JK-Audio Fax: 815-786-8502
Info@jkaudio.com www.jkaudio.com
Copyright © 2006 JK Audio, Inc.. All Rights Reserved.
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