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Showing posts with label telephone. Show all posts
Showing posts with label telephone. Show all posts

Telephone call Voice Changer

Posted by Unknown Sunday, October 6, 2013 0 comments

Voice manipulation device specially intended for props, 9V Battery operation

Although this kind of voice effect can be obtained by means of some audio computer programs, a few correspondents required a stand-alone device, featuring microphone input and line or loudspeaker outputs. This design fulfills these requirements by means of a variable gain microphone preamplifier built around IC1A, a variable steep Wien-bridge pass-band filter centered at about 1KHz provided by IC1B and an audio amplifier chip (IC2) driving the loudspeaker.

Parts:
P1______________10K Log. Potentiometer
R1,R10__________10K 1/4W Resistors
R2_______________1K 1/4W Resistor
R3______________50K 1/2W Trimmer Cermet or Carbon
R4,R6,R7,R14___100K 1/4W Resistors
R5______________47K 1/4W Resistor
R8______________68K 1/4W Resistor
R9_______________2K2 1/2W Trimmer Cermet or Carbon
R11_____________33K 1/4W Resistor
R12_____________18K 1/4W Resistor
R13_____________15K 1/4W Resistor
C1,C2,C3,C8,C9_100nF 63V Polyester Capacitors
C4______________10µF 25V Electrolytic Capacitor
C5_____________220nF 63V Polyester Capacitor (Optional, see Notes)
C6_______________4n7 63V Polyester Capacitor
C7______________10nF 63V Polyester Capacitor
C10____________220µF 25V Electrolytic Capacitor
IC1___________LM358 Low Power Dual Op-amp
IC2_________TDA7052 Audio power amplifier IC
MIC1__________Miniature electret microphone
SPKR______________8 Ohm Small Loudspeaker
SW1____________DPDT Toggle or Slide Switch
SW2,SW3________SPST Toggle or Slide Switches
J1____________6.3mm or 3mm Mono Jack socket
B1_______________9V PP3 Battery (See Notes) Clip for PP3 Battery

Notes:
  • The pass-band filter can be bypassed by means of SW1A and B: in this case, a non-manipulated microphone signal will be directly available at the line or loudspeaker outputs after some amplification through IC1A.
  • R3 sets the gain of the microphone preamp. Besides setting the microphone gain, this control can be of some utility in adding some amount of distortion to the signal, thus allowing a more realistic imitation of a telephone call voice.
  • R9 is the steep control of the pass-band filter. It should be used with care, in order to avoid excessive ringing when filter steepness is approaching maximum value.
  • P1 is the volume control and SW2 will switch off amplifier and loudspeaker if desired.
  • C5 is optional: it will produce a further band reduction. Some people think the resulting effect is more realistic if this capacitor is added.
  • If the use of an external, moving-coil microphone is required, R1 must be omitted, thus fitting a suitable input jack.
  • This circuit was intended to be powered by a 9V PP3 battery, but any dc power supply in the 6 - 12V range can be used successfully.
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Telephone Call Recorder

Posted by Unknown Thursday, August 15, 2013 0 comments
Today phone has become an integral part of our lives. It is the most widely used communication tool in the world. Owing to its immense popularity & widespread use, there arises a necessity for call recording devices, which find application in call cent-res, stock broking firms, police, offices, homes, etc. Here they are describing a call recorder that makes use of only a few parts. But in order to understand its working, must first have the basic knowledge of standard phone wiring as well as a stereo plug.


In India, land-line rings primarily use RJ11 wiring, which has wires-tip and ring. While tip is the positive wire, ring is the negative. And together they complete the phone circuit. In a phone line, voltage between tip and ring is around 48V DC when handset is on the cradle(idle line). In order to ring the phone for an incoming call, a 20Hz AC current of around 90V is superimposed over the DC voltage already present in the idle line. The negative wire from the phone line goes to IN1, while the positive wire goes to IN2. Further, the negative wire from OUT1 and the positive wire from OUT2 are connected to the phone. All the resistors used are 0.25W carbon film resistors and all the capacitors used are rated for 250V or more.


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Telephone Wire Single Pairtelephone Wire

Posted by Unknown Tuesday, June 4, 2013 0 comments
Telephone Wiring on Telephone Socket Wiring Diagram
Telephone Socket Wiring Diagram.


Telephone Wiring on Telephone Socket Wiring How To Do It
Telephone Socket Wiring How To Do It.


Telephone Wiring on Telephone Wiring Full Screenshot Telephone Wiring Demo
Telephone Wiring Full Screenshot Telephone Wiring Demo.


Telephone Wiring on Residential Telephone Wiring Basics
Residential Telephone Wiring Basics.


Telephone Wiring on Rj14 Two Line Telephone Wiring
Rj14 Two Line Telephone Wiring.


Telephone Wiring on Uk Telephone Wiring
Uk Telephone Wiring.


Telephone Wiring on Telephone Wire Color Codes
Telephone Wire Color Codes.


Telephone Wiring on Example Of A Correctly Wired Wall Jack
Example Of A Correctly Wired Wall Jack.


Telephone Wiring on Telephone Wire Single Pair 0 5 Mm Telephone Wire Two
Telephone Wire Single Pair 0 5 Mm Telephone Wire Two.


Telephone Wiring on Telephone Jacks Mount The Telephone Jack
Telephone Jacks Mount The Telephone Jack.


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