Telephone Circuits, Page 1

Telephone Circuits, Page 1
Telephone Circuits: #-A B-C D-F G-N O-S T-Z
Last Updated on: Friday, February 05, 2010 10:06 AM

Circuits Designed by Dave Johnson, P.E. :

1 LINE TELEPHONE LINE STATUS INDICATOR
This circuit is similar to the above circuit, but only monitors one phone line.

2 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.

2.45GHz RF Signal Detector
This passive RF indicator is made from a few simple parts. A 100uA moving coil meter is used to display the relative intensity of the RF signal. This circuit can be used with some cell phones and many cordless telephones. (added 7/06)

4 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.

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

1 Line Telephone Line Status Indicator - This circuit is similar to the above circuit, but only monitors one phone line. ….(designed by David A. Johnson)

10 Reasons to Upgrade to a 16800 or 16900 Series Logic Analyzer - ...application note is...internal Xilinx and...packet level to...buses . .. 4 3...integrity by quickly...Trace Core) core...Interface, POS PHY...Agilent Application Note 2007-12-03 (app note added 6/06)

2 Line Intercom Plus a Telephone Changeover Switch - circuit presented here can be used for connecting two telephones in parallel and also as a2-line intercom. (added 6/06)

2 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. ….(designed by David A. Johnson)

2.45GHz RF Signal Detector - This passive RF indicator is made from a few simple parts. A 100uA moving coil meter is used to display the relative intensity of the RF signal. This circuit can be used with some cell phones and many cordless telephones. (added 7/06) ….(designed by David A. Johnson)

3.5 mm or 6.25 mm Stereo Telephone plug - ….(electronic schematic added 03/08)

3.5 mm or 6.5 mm Mono Telephone plug - ….(circuit design added 03/08)

300 baud modem circuit schematic - La plupart des modems de type Baycom comportent des circuits qui sont devenus difficiles à trouver, surtout si l'on veut pratiquer le packet à 300 bauds. Une alternative consiste à utiliser plusieurs circuits intégrés qui existent encore, et qui, finalement, reviennent moins cher. Cependant....(circuit added 04/05/06)

4 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. ….(designed by David A. Johnson)

5 Band Graphic Equalizer using a Single IC/Chip - This circuit uses a single chip, IC BA3812L for realizing a 5 band graphic equalizer for use in hi-fi audio systems. BA3812L is a five-point graphic equalizer that has all required functions integrated onto one IC. IC is comprised of five tone control circuits and input and output buffer Amplifiers.…. (added 10/05)

56K RF Modem - (circuit / schematic added 6/05)

60 MCurrent Source Feeds Telecomm Lines - 12/12/97 EDN-Design Ideas: (design idea added 6/06)

8 Line Intercommunication using 89c51 - ….(design added 08/08)

9-Line Telephone Sharer - (electronic Circuit / Schematic added 10/04)

9-pin null modem cable - (Tony van Roon's circuit / schematic added 6/05)

ADSL Modems that Use the LT1886 as a Line Driver Yield Long Reach and Fast Data Rates - DN240 Design Notes (Linear Technology) (app note added 1/06)

Advances in High Speed Design in Dispersively Attenuating Environments Circuit Boards and Cables - ...deals with advances made in methods for...aiding the design and analysis of high performance digital...through dipersively attenuating paths. Agilent Application Note 2002-04-10 (app note added 06/06/06)

Alarm Phone Dialer with MT8880 and PIC 16F84A - Just hook this Alarm Phone Dialer up to something you would like to monitor, for example, a high water alarm, low temperature alarm, back window, garage door, etc. When the system is activated it will call a number of programmed numbers to let you know the alarm has been activated. This would be great to get alerts of alarm conditions from your home when you are at work. The microcontroller code is provided on the site. ….(design added 11/08)

AN-1034: An Optimized DCE Interface for V.34 Modems using the DS8933 and DS8934 Line Drivers and Receivers - National Semiconductor Application Note (app note added 2/06)

AN106 Quick CS6420 Speakerphone Interface - (app note added 6/07)

AN-214: Ground Rules for High Speed Circuits - AN-214 Analog Devices Application Notes (app note added 6/06)Layout and Wiring Are Critical in Video Converter Circuits.

AN237: TCP/IP Library Programmer's Guide - Silicon Labs Application Notes (app note added 6/06)

AN-347: Shielding and Guarding - AN-347 Analog Devices Application Notes (app note added 6/06)How to Exclude Interference-Type Noise. What to do and Why to do it-A Rational Approach

AN-444: Single Chip Modem Provides Low-Cost Data Communication - National Semiconductor Application Note (app note added 2/06)

AN-466: Improving the Performance of a High Speed PBX Backplane - National Semiconductor Application Note (app note added 2/06)

AN-521: Dual Tone Multiple Frequency DTMF - National Semiconductor Application Note (app note added 2/06)

AN-666: DTMF Generation with 3.58 MHz Crystal - National Semiconductor Application Note (app note added 2/06)

AN-772: A Design and Manufacturing Guide for the Lead Frame Chip Scale Package LFCSP - AN-772 Analog Devices Application Notes (app note added 6/06)

AN833: Microchip TCP/IP Stack Application Note - Microchip Application Note Published 6-Mar-02 (app note added 2/06)

AN854: Connecting a Picmicro® Microcontroller to a Standard Analog Telephone Line - Microchip Application Note Published 21-Aug-02 (app note added 6/06)

AN-D27: DMOS Devices for Telecommunications - Supertex Semiconductors (app note added 2/06)

Assorted telephone circuits - (circuit / schematic added 6/05)

Audio Graphic Equaliser - Simple 7 band eqalizer (diagram added 2/07)

Audio Visual Indicator for Telephones - Many a times one needs an extra telephone ringer in an ad joining room to know if re is an incoming call. For example, if telephone is installed in drawing room you may need an extra ringer in bedroom. All that needs to be done is to connect given circuit in parallel with existing telephone lines using twin flexible wires. This circuit does not require any external power source.... (added 10/05)

Audio Visual Ringer - Many a times one needs an extra telephone ringer in an adjoining room to know if re is an incoming call. For example, if telephone is installed in drawing room you may need an extra ringer in bedroom. All that needs to be done is to connect given circuit in parallel with existing telephone lines using twin flexible wires. This circuit does not require any external power.... (added 10/05)

Telephone Circuits: #-A B-C D-F G-N O-S T-Z