Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com has links to 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.

HOME Schematics Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches
Welcome to DiscoverCircuits.com - online since 2002

See Media Kit for
Advertising Opportunities

Attention Designers:  Please alert us by eMail if we have linked to sites
where your original material has been copied without your permission.
We will change to the LINK to your site.  
Thank you.

 


Telephone Circuits

Telephone Circuits:   #'s - B       C - F       G - K       L - Q       R - S      T - Z

Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :
Telephone Status Indicator for 4 Lines -  Many home businesses use multiple phone lines.  This circuit gives you a visual indication when a line is in operation.  The two AA battery cells should provide enough power for about one year of operation . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Two Line Telephone Line Status Indicator -  Many home businesses use multiple phone lines.  This circuit gives you a visual indication when a line is in operation.  The two AA battery cells should provide enough power for about one year of operation.  The circuit is line polarity insensitive . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Telephone Operated Remote Control using PIC16F84a MicroController -  This design controls up to 8 devices using a PIC  microcontroller (PIC 16F84A) connected to the phone line.  The unique feature here is that unlike other telephone line based remote control, this device does not need the call to be answered at the remote end so the call will not be charged.  This device depends on number of rings given on the telephone line__ 

Telephone PBX -  I've been facsinated with telecommunications from an early age.  When I was twelve or so I had an intercom system from which I could talk to most of the house from my corner of the kids' room.  it was made out of the amplifier from a record player, and miscellaneous parts from old TV sets.  When I was fourteen someone gave me a WW2 vintage shortwave receiver with a blown power supply.   __ Designed by Markus Wandel

Telephone Receiver -  This simple telephone receiver without a dialling section can be connected in parallel to a telephone line.  it can be easily assembled on a small vero board or a PCB.  A...__ Electronics Projects for You

Telephone Recorder -  This circuit lets you record your ph1-conversations automatically, notice that this circuit does not provide isolation between Telephone line and the recorder.   __ Designed by Aaron Cake

Telephone Recording -  How they work and some example  __ Designed by Tomi Engdahl

Telephone Remote Switch -  This device connects to the telephone line and can be used to remotely control up to 4 relay outputs using a DTMF (tone dialing) telephone.  A number of user settings are available to improve the useability and security of the device.  The kit comes complete with a small plastic case with silk-screened front and rear panels.  __ 

Telephone Ring Generator using 60hz Power Transformer -  This ring generator will ring a telephone once every 10 seconds.  The interval between rings can be lengthened or shortened by varying the value of the 1 Meg resistor.  The 70 volt/ 30 Hz ring voltage is produced from the 120 volt side of a small 12.6 VAC power transformer __ Designed by Bill Bowden

Telephone Ring Generator using Switching Power Supply -  The telephone ring generator shown below generates the needed high voltage from a simple switching mode power supply (SMPS) which employs a CMOS Schmitt Trigger square wave oscillator, 10 mH inductor, high voltage switching transistor (TiP47 or other high voltage, 1 amp transistor) and a driver transistor (2N3053).  The inductor should have a low DC resistance of 1.5 ohms or less.  The switching supply must have a load connected to prevent the voltage from rising too high, so a 22K resistor is __ Designed by Bill Bowden

Telephone Ringer -  Several design, scroll to find the one.  The Phone Ringer circuit will work with any ordinary phone including older bell ringer types.  The circuit rings the phone in a completely realistic manner until someone answers.  When the receiver is lifted the user hears the audio of your choice.  it might be another telephone, a tape recording, a favorite talk radio show, a fake busy-signal, a scanner tuned to weather or police, cues for the actor who forgot his next line, or whatever audio source strikes your fancy.  DC current is passed through the phone to activate the phone’s electronics. __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Telephone Ringer by IC KA2411 -  Simple telephone Ringer with KA2411 IC .  __ 

Telephone Ringer using 555 Dual Timers -  Using modulated rectangular waves of different time periods, The circuit presented here produces ringing tones similar to those produced by a telephone.  The circuit requires four astable multivibrators for its working.  Therefore two 556 ICs  are used here.  The IC 556 contains two timers (similar to 555 IC s) in a single package.  One can also assemble__ 

Telephone Ringer using Timer ICs -  This circuit can produce ringing tones similar to those produced by a telephone for use in intercom operations.  __ Electronics Projects for You

Telephone Ringings -  how to detect ringing and how to make phones ring __ Designed by Tomi Engdahl

Telephone Ring-Tone Generation -  DN134 Design Notes __ Linear Technology/Analog Devices

Telephone Sentry -  it is quite common to find extension phones in homes these days but this kind of convenience also comes with a distinct disadvantage: the possibility of another person listening in.  This...__ Electronics Projects for You

Telephone Status Indicator -  "Hello"  meet BUSYER-7Z.  The BUSYER-7Z is an educational telephone line busy indicator kit.  it lets you know if someone else is on the phone, line in-use (line is off-hook) before you picking up.  Large bright LED will indicate the phone line in-use status.  No more “Ops, ” “i’m sorry, ” “I didn’t mean to interrupt, ” “i’m on the phone.  ” The BUSYER-7Z will light when the phone line is off-Hook.  it will ends interruptions by indicating that you are “On the phone.  ” __ Contact Kit from Elich Industrial Development, Corp

Telephone Status Indicator for 4 Lines -  Many home businesses use multiple phone lines.  This circuit gives you a visual indication when a line is in operation.  The two AA battery cells should provide enough power for about one year of operation . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Telephone Tap -  Amplify or record a telephone call with the simple circuit shown.  The 8-W secondary winding of a miniature transistor output transformer is connected in series with either of the telephone lines.  The 1000-W primary winding can feed either a cassette recorder or an audio amplifier__ 

Telephone Test with Audio Mixer -  I have used this type of circuits for quick testing of telephone equipment.  This is a quick hack that does not exactly resemble the characteristics of the real telephone network, but is enough for this kind if applications.  if you want better simulation, change the resistor to 600 ohm and increase the power supply voltage.  And by the way you can also feed signals to telephone if you connect the circuit output wires to small amplifier output.   __ Designed by Tomi Engdahl

Telephone Voice Changer -  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 IC 1A, a variable steep Wien-bridge pass-band filter centered at about 1KHz provided by IC 1B and an audio amplifier chip (IC 2) driving the loudspeaker.  __ 

Telephone Ringer -  This circuit generates the sound of the electronic ringer found in modern telephones, supplanting the 2-bell electromechanical ringers used previously.  The ringing pattern follows the United States convention of 2 seconds on, and 4 seconds off.  During the "on" interval, the tone alternates between two selectable frequencies at a rate of 20Hz.  Refering to the schematic, NAND Schmitt trigger U1A is configured as a relaxation oscillator, adjusted with RV1 for a 40Hz waveform at test point TP1 __ Designed by Arthur Harrison

Telephone: Music On Hold -  Waiting a call hold can be boring if there is only silence on the line.  it’s a good thing to present an “easy music”  in call hold, make a long waiting time feels much shorter.  This simple circuit (consists of diodes, SCR, and some passive components) allows to place the caller on hold in one room then answer the phone again at another place, or at same phone at later time after doing something.__ 

Telephone-Operated Calling System -  Dual-tone multiple-frequency (DTMF) receiver IC is commonly used in telephone equipment.  One common DTMF receiver is Holtek HT9170 used in electronic communication circuits.  The Holtek HT9170 series comprises DTMF receivers integrated...__ Electronics Projects for You

Teleremote Control -  Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines.  it can be used to switch appliances from any distance, overcoming the limited range of...__ Electronics Projects for You

Teletext Devices -  Specifications and designs are subject to change without notice.
Use on your own risk. __ Designed by Mijo Kovacevic, S51KQ

The Cheap But Useful ErICsson Cell Phone Display GA631 -  You used to have an Ericsson Cell Phone GA628 and you also loved it very much, however after few years of using, you’ve decided to change a brand new cell phone and you just threw it inside the drawer and never touch or look on it after that?__ 

The KD2BD Pacsat Modem -  The KD2BD Pacsat Modem is a low cost, high performance 1200 bps BPSK modem designed to interface between a packet radio terminal node controller (TNC) and an amateur satellite ground station, and allows full-duplex access to the 1200 baud "Pacsat" constellation of amateur satellites. __ Designed by John A. Magliacane, KD2BD

The Link 4+0-Internal Intercom -  This version of the Link provides four internal intercom phones with no outside line access. __ Contact IQ Technologies

The Link A2B+1 (the Link Telephone Intercom-DTMF version) -  Since the recent publication of ‘The Link Telephone intercom’ on the net, a number of email requests have come in asking for a DTMF version, with 2 or more phones that can in fact access an outside line.  So, back to the ‘drawing board’ (read: PC screen) I went, and what you see above (somewhat more complicated, but nevertheless extremely reliable design) is the result of some ten hours of designing, building and testing not one, but two identical Link circuits.  The original DTMF version is now set up between my bed sitter unit at the back of my shop – extension #1, and my elderly next door neighbour, who lives in the unit behind the shop – extension #2.  it is proving very handy and although my outside line is not connected to that version at this stage, initial tests proved that both making and receiving calls works perfectly __ Contact IQ Technologies

The Link P-Privacy Link! (Telephone Intercom) -  This version of the Link goes beyond anything previously attempted by me in the area of telephone type projects.  Having achieved genuine ring trip (not that hard, but a bit tricky to design with 'off the shelf' $5 components first time around...)  __ Contact IQ Technologies

The Link Telephone Intercom  -  The Link circuitry is simple and efficient, employing just two IC s, half a dozen transistors, and a handful of garden variety components.  it all runs on 12 volts and is easily assembled.  You can have your own home intercom between the kitchen, the garage, the rumpus room and at your poolside ‘barby’ and all for less than $100!  The Link intercom __ Contact IQ Technologies

The Original 2 Phone Link Design -  This is the circuit that sparked off all the other Link Telephone intercom designs.  Originally designed back in 1996 with heavy duty relays and their contact banks, it was updated late last year with the addition of IC 1 in place of a simpler transistor multivibrator, the replacement of all relays and contact banks with optocouplers, and the addition of the two transformers as part of the transmission bridge (see explanation below) which was comprised partly of the relay coils.  if you just want simple ‘no frills’ communication from one phone to another, then this is the right circuit for you!  __ Contact IQ Technologies

The Surfer’s Preserver -  Several design, scroll to find the one.   The Surfer’s Preserver is a simple device that prevents other phones in the house from disrupting your critical internet session by disconnecting them from the line while you surf!  The circuit is also useful in preventing eavesdropping from other extensions since other phones are "dead" until you hang up.  The circuit wires in series with either of the offending phone’s wires (red or green) and it is small enough to tuck behind the wall cover plate.  which interests you. __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Tiny Efficient High Power LED Camera Flash Solutions for Cell Phone Applications -  Design Notes 231__ Linear Technology/Analog Devices

TM-441 9k6 packet Modification -  Schematic only __ Designed by Guy Roels ON6MU

Top 20 Android Project Ideas -  There is a lot of confusion among students when it comes to projects. Now-a-days almost everybody is aware of Android and its features. Android projects are a preferable option because of __  10/6/2016 - EFY

Transistorised intercom -  Several intercom circuits have appeared in EFY using integrated circuits.  The circuit described here uses three easily available transistors only.  Even a beginner can easily assemble it on a piece of...__ Electronics Projects for You

Translate a laW to m law -  05/07/98 EDN Design Ideas:  (NOTE: contains several ideas, scroll down) Two common methods exist to compand voice for transmission through a PCM channel.  in Europe, A law involves converting a 12-bit input signal to an 8-bit encoded output.  in the US, m law involves encoding 13 bits to 8 bits.  You can use a translator to convert from A law to m law (Figure 1).  The converter is asynchronous and requires only an 8-bit A law input to provide an 8-bit m law output. __ Circuit Design by Rolando Herrero, Instituto Tecnológico de Buenos Aires, Argentina

Two Line Intercom Plus a Telephone Changeover Switch -  The circuit presented here can be used for connecting two telephones in parallel and also as a 2-line intercom.  Usually a single telephone is connected to a telephone line.  if another telephone is required at some distance, a parallel line is taken for connecting the other telephone.  in this simple parallel line operation, the main problem is loss__ 

Two Line Telephone Line Status Indicator -  Many home businesses use multiple phone lines.  This circuit gives you a visual indication when a line is in operation.  The two AA battery cells should provide enough power for about one year of operation.  The circuit is line polarity insensitive . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Two way Simple Circuit Very Small Telephone Exchange -  This is a very small telephone exchange attached only two ordinary Tele phones. Fully bi-directional facility with an intercom system. When a phone is in off hook condition , Exchange will detect it & send ringing pulse to other phone. When it will be picked up , the connection will be established between both phones. This will be taken place vice-versa. __ Contact IQ Technologies

Two-Line Intercom cum Telephone Line Changeover -  The circuit presented here can be used for connecting two tele phones in parallel and also as a 2-line intercom.  Usually a single telephone is connected to a telephone line.  if another __ Designed by © EFY Enterprises Pvt. Ltd.

      <<<         >>> 

Got Designs?
Please eMail
if you want me to link to and/or post your original design.  Thanks.


Telephone Circuits:   #'s - B       C - F       G - K       L - Q       R - S      T - Z

 


Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches



 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |   
Privacy Policy


Discovercircuits.com endeavors to credit original designers.   Please alert us by eMail so we can
delete links to material that have been copied without your permission
.   Thank you.


© Copyright of all original material on this website is the property
of David A. Johnson, P.E. (Dave Johnson & Associates ) unless otherwise noted.  

Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.
All material is provided "as is" without guarantees or warranty of any kind, either expressed or implied.