Telephone Recorder


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This nifty little circuit lets you record your phone conversations automatically. The device connects to the phone line, your tape recorder's microphone input, and the recorder's remote control jack. It senses the voltage in the phone line and begins recording when the line drops to 5 volts or less.

Schematic

This is the schematic of the Telephone Recorder

Parts

Part
Total Qty.
Description
Substitutions
R11270K 1/4 W Resistor
R211.5K 1/4 W Resistor
R3168K 1/4 W Resistor
R4133K 1/4 W Resistor
C110.22uF 150 Volt Capacitor
Q1, Q222N4954 NPN Transistor
D111N645 Diode
MISC1Wire, Plugs To Match Jacks On Recorder, Board, Phone Plug

Notes

  1. The circuit can be placed anywhere on the phone line, even inside a phone.
  2. Some countries or states require you to notify anyone you are talking to that the conversation is being recorded. Most recoders do this with a beep-beep. Also, you may have to get permission from the phone company before you connect anything to their lines.

Related Circuits

Ringing Phone Light Flasher, Phone Busy Indicator, FM Telephone Bug, Cut Phone Line Detector, Simple Phone Tap, Telephone Hold Button, Telephone Recorder, Remote Telephone Ringer

Comments

Add A Comment

anonymous
Telephone Recorder
Wednesday, November 23, 2022 3:24:01 AM
I agree with the previous comment. An isolation transformer in the recorder Mic output is necessary. Also, a small bridge rectifier placed in the telephone input serves to iron out any reverse polarity issues. With those two modifications, this circuit works very well and is far simpler than most. Substitute freely--the switch mechanism is not that fussy. Thanks.
anonymous
Telephone Recorder
Saturday, April 27, 2013 11:57:01 PM
If you connect any expensive recording device to a telephone line without complete DC isolaation you risk burning out componnets on the device, not really woth wrecking a PC or its soundchip just to save on a cheap audio isolation transformer. Nowadays PSTN lines are often fitted with incorrect polarity too... without isolation you will lilkely get a nasty hum if you are fortunate or silence of a fried motherboard if you are not so fortunate.
osmus
Telephone Recorder
Monday, March 21, 2011 7:11:15 PM
wihout a line isolation with transformer its a bad idea to plug your mic to phone.
Harry
Telephone Recorder
Friday, April 02, 2010 9:52:42 AM
Can somebody mail me the circuit details. I need this to record my meeting and will help me plan my communication/actions better. Currently I use the speaker phone and have problem with noise when I speak into it.
anonymous
Telephone Recorder
Thursday, September 24, 2009 10:13:23 AM
This Telephone Recorder is fucking rad!
anonymous
Telephone Recorder
Friday, October 31, 2008 12:39:15 AM
its a nice circuit idea. Simple one. Nothing new though.
Rao Waseem
Telephone Recorder
Thursday, May 08, 2008 3:40:12 AM
this is very useful project.i liked it very much if u can any comments u can mail me.
sagar
Telephone Recorder
Thursday, February 28, 2008 3:57:06 AM
if u dont mind pls mail me the complete info,block diagram,circuit diagram&major advantages ,applications of this project which helps me in doing my mini project
navaneeth
Telephone Recorder
Tuesday, February 19, 2008 6:40:26 AM
would youmind pls mail me the complete info,block diagram,circuit diagram&major advantages ,applications of this project which helps me in doing my mini project. what is remote control jack stands here for?
antany
Telephone Recorder
Tuesday, January 22, 2008 12:13:53 PM
where should we connect the inputs (on which phone line)
hulu beliku
Telephone Recorder
Wednesday, January 16, 2008 6:08:39 AM
would youmind pls mail me the complete info,block diagram,circuit diagram&major advantages ,applications of this project which helps me in doing my mini project
sushanth
Telephone Recorder
Thursday, January 10, 2008 9:25:54 PM
please tell me the circuit analysis and about remote control jack
hossam
about the Telephone Recorder circuit
Tuesday, December 04, 2007 1:08:57 PM
i just need more information about this circuit because i have to design it ,,and i need to know what each part of this circuit do ? wait 4 ur reply ,,and i hoep it come soon
pallavi
Telephone Conversation Recorder
Wednesday, November 28, 2007 4:35:52 AM
if u dont mind pls mail me the complete info,block diagram,circuit diagram&major advantages ,applications of this project which helps me in doing my mini project
hashim mahmoud
Telephone Recorder
Wednesday, November 21, 2007 3:07:16 PM
hi can u help me to do this project.by sending it's complete info. & circuit analysis & its major advantages to my mail id. thanks.
Rajkumar
Telephone Recorder
Thursday, November 01, 2007 4:06:51 AM
Hi, Iam rajkumar from chennai, India.I am ruing a concern in chennai.so I feel like some problem was going on with our workers pl. send the details of thie phone recorder to record the conversation between the workers nd the clients
psalmmuel s ashaolu
Telephone Recorder
Tuesday, October 16, 2007 1:22:15 PM
can you please sent me details on this cct
psalmmuel s ashaolu
Telephone Recorder
Tuesday, October 16, 2007 1:20:33 PM
the schematic cct is quite great, i will love to try it on my own. i give kudos to the designer.
ovidiu
Telephone Recorder
Wednesday, October 10, 2007 4:51:03 PM
The control jack is for start/stop the recorder equiped with REM (remote) jack
usman khalid
ELECTRONICS PICS
Friday, September 21, 2007 3:49:22 PM
sir, this website absolutely first class but if u give us the original pics of circuit components with schematic as well then it is better this site become unique site then the others. also, it help 4 them who r new in this field. thanx
rohit garg
telephone conversation recorder
Thursday, September 20, 2007 11:37:07 PM
i want to get a help about this project ,i want to get the full description with their circuit diagram and their theory
JOEL
QUESTION
Friday, September 14, 2007 2:25:50 PM
HI, I NEED HELP WITH A PROJECTE, DOU U HAVE A CIRCUIT OF DETECTION OFF HOOK TELEPHONE BUT OF CENTRAL
gurdeep;
Telephone Recorder
Wednesday, September 05, 2007 11:45:06 AM
will u help me to do this project.by sending it's complete info. & circuit analysis & its major advantages to my mail id. thanks.
divya.k
Telephone conversation Recorder
Friday, August 31, 2007 5:47:08 AM
if u dont mind pls mail me the perfect circiut and details of this project which helps me in doing my mini project.
ASIFA INAMDAR
Telephone Recorder
Tuesday, August 28, 2007 1:05:05 AM
Pls give me the more information about this circuits & about cost also thanks.waiting for your reply
seth sarpong adjei
Telephone Recorder
Tuesday, August 21, 2007 12:41:40 PM
Please i want you to send me the detail information about this project, to enable me perforem it. Thanks you.
suraj
Telephone Recorder
Wednesday, August 08, 2007 10:51:29 PM
i want to do this project.so i need the necessary information about this project.can u please mail me the necessary details about this project.will this circuit really works? Thans you... Suraj.
gokhan cag
Telephone Recorder
Tuesday, August 07, 2007 1:47:07 PM
what is the function of control jack? nobody has explained it clearly...
Debra Howard
Telephone Recorder
Friday, August 03, 2007 9:05:56 PM
I purchased an inexpensive recorder and a little gadget that you hooked to it to plug into the wall. I was using this on someone that I suspected stilling medication. However, I have a lawsuit going on because I was hurt very badly and the only way I could get this man out of my house was to move out and have the utilities cut off. So this is what I did, however, because he is bipolar and on "no medication" he resented what I had done however he hadn't worked to contribute any money into the house hold in two years. Anyway, he always seemed to have money without working and I was always very short on medication. So I went to a safe shop and purchased a used drop money box and then about two months later I moved out with my mother in order to get rid of this man. While he was leaving, he made the comment to me "you just wait until they put me on the stand". This man lies about "everything". If you say white, he says black. Anyway, after I had the utilities cut off and he finally moved out, he found my little recorder and the line gadget that hooked up to it in order to record my phone. My question is, Is there any way I can tell when I answer this phone or call this number if he is using this on me now? He is now living with someone else with cell phones and house phones. Are there any sounds I can listen for or anything I can key into the phone to see if it's being taped? Please help if you can. My mediation is next week and I'm sure if they have his recordings, he will turn them in to something there not. Can you please please help?????
Jim
Telephone Recorder
Monday, July 30, 2007 1:01:58 PM
To make this a REALLY useful circuit, you should place a DTMF decoder in-line with the audio so the circuit can listen for a keypad key press and shut the recorder off. There are no affordable telephone recorders out there with this capability, i.e. recorder comes on when phone is picked up (like now), but if listener doesn't want to contuinue recording, they can press a key on phone keypad and shut recorder off. Awesome feature.
Gastón
Telephone Recorder
Saturday, July 21, 2007 1:23:57 PM
Hi, can i inject audio in the phone line by using this circuit??
ramesh
Telephone Recorder
Monday, July 16, 2007 5:50:34 AM
please sent me brief description of each components and the projects
pushpendra
Telephone Recorder
Sunday, July 15, 2007 3:49:38 AM
will u help me to do this project.by sending it's complete info. & circuit analysis & its major advantages to my mail id. thanks.
Neeraj
Telephone Recorder
Thursday, July 12, 2007 4:53:37 AM
Can u plzz specify da device 2 wich da MIC JACK gets connected?
rekha
Telephone Recorder
Sunday, July 01, 2007 9:00:01 AM
i want to do this project.so i need the necessary information about this project.can u please mail me the necessary details about this project.will this circuit really works?
raza
Telephone Recorder
Thursday, June 07, 2007 1:45:50 PM
has anyone tried this circuit?? can u plz tell me if it works or not!!
anonymous
Telephone Recorder
Thursday, May 24, 2007 2:13:47 PM
control jack????

(Editor's notes: Read previous comments.)

Sebastiaan
Telephone Recorder
Thursday, May 24, 2007 2:05:58 PM
The remote control jack is nothing more than an electronic switch (like a relay) which you will have to put between one of the power supply wires of your recorder (battery or adapter). Than as soon as the hook is lifted this "remote output" will allow power to your recorder and the recorder starts running. If you have placed your recorder in the recorder setup, this will mean it will start recording emideatly as soon as the hook has been lifted. The audio section however is not that advanced and it would be safer for your recorder (and improved quality) to use an old audio transformer from an old telephone (see link http://www.engadget.com/2005/09/27/how-to-build-a-telephone-recording-circuit-from-an-old-modem/) Have fun building
anonymous
Telephone Recorder
Wednesday, May 23, 2007 6:04:47 AM
please i want proper explanation for designing this phantagloriuos project.tthe information can be texted to the e-mail adress
Zuberi
Telephone Recorder
Wednesday, May 16, 2007 3:44:50 PM
hi ...ma question ...if we put the lines of microphone in computer,s mic port or line in port.......then is it possible to record the call by any recording software .......ass the same funcation occur in mic recoriding in computer ....and also tell me the funcation of remote control jack ...........is this line are for sum supply ?? or there is sum other function on it ..........waiting for ur reply ...........
xia
Telephone Recorder
Monday, May 14, 2007 5:24:20 PM
good
xia
Telephone Recorder
Monday, May 14, 2007 5:22:24 PM
not very bad
Franklin L
Telephone Recorder
Friday, May 11, 2007 2:06:14 PM
The remote control jack is located in the a Controlled Tape Recorder device. usually in most of Tape recorder http://www.radioshack.com/search/index.jsp?kwCatId=&kw=telephone%20recorder&origkw=telephone%20recorder&sr=1
anonymous
Telephone Recorder
Thursday, May 10, 2007 5:31:33 AM
THANKS TO PUBLISH THIS TYPE OF CIRCUITS,KINDLY GUIDE ME HOW I CAN CONVERT MECHANICAL CAM OR GEAR MOVEMENT IN TO DIGITAL AND RECORD IN PC LIKE HUNDRED PLACED DATA TO BE GATHERED BY DATA LOGGER AT ONE PLACED ON PHYSICAL LINE. THANKING YOU YOURS FAITH FULLY M.Y.GANU.
hamad
Telephone Recorder
Tuesday, May 08, 2007 12:12:59 PM
what is remote control jack..???? and its constructional idea. is there effect on line?
umair
Telephone Recorder
Saturday, April 28, 2007 9:16:54 AM
control jack?????plz explain its constructrion and working in detail......
bety
Telephone Recorder
Tuesday, April 24, 2007 12:06:19 PM
very good
anonymous
Telephone Recorder
Friday, April 13, 2007 3:58:48 AM
remote control jack???????????????????
anonymous
Telephone Recorder
Wednesday, April 04, 2007 12:31:36 PM
its quite a perfect idea but it shall have some amelioration
anonymous
Telephone Recorder
Sunday, April 01, 2007 4:17:20 AM
what is remote control jack..???? and its constructional idea.
vinay
Telephone Recorder
Friday, March 23, 2007 10:26:12 AM
give some deatils about circuitry and working of it .. please
mazhar
Telephone Recorder
Monday, March 12, 2007 1:24:05 AM
working principle of telephone recorder
mazhar
Telephone Recorder
Monday, March 12, 2007 1:22:37 AM
function of telepjone recorder
romany
Telephone Recorder
Monday, March 05, 2007 2:30:20 PM
is there effect on line?
vaibhav
Telephone Recorder
Monday, March 05, 2007 6:29:37 AM
This circuit can prove to be of quiet a help in some cases... To me it seems a perfect minor project.
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