Protection For Telephone Line
A long time ago when telephones were so simple almost nothing could go amiss from an electrical point of view, Telecom operators installed surge protection on a...
Electronic Telephone Ringer
This circuit produces a ringing sound similar to that made by more recent telephones. It consists of three almost identical oscillators connected in a chain, ea...
1945 RCA CRV-59AAE Iconoscope Camera
CRV-59AAE is 20" long by 9" wide by 10"high. It weighs a mere 33 pounds. It is at least 60 years old and in excellent condition. It represents some of the fines...
FaxCon
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PRUBY Documentation
The PRUBY module that provides a PLL interface for rubidium frequency references such as the LPRO-101 and FRS-C products manufactured by EFRATOM Ball, Inc. The ...
Parallel Port CW Interface for N3FJP
I`ve been doing some CW contesting with my K2 and N3FJP`s Logging Software and since I now have this modern rig with computer control and everything I wanted to...
Kodiak Military History Fire Control Telephones
The EE-91 is a wall mounted metal telephone box. It is a common battery phone which means transmitter current is obtained from the central office battery. It is...
EE-8 Field Telephone
One is in a leather bag and is model EE-8-A. One or more is in a canvas bag and is EE-8-B. All have handsets with the butterfly push-to-talk lever. The -B model...
Telephone Technical References
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Utah T1-Rate Modem
This is a "quick-and-dirty" page that I set up to describe the T1-rate modem that I designed several years ago (in 1993, actually. ) Let me point out that unles...
PIC-based PSK31 MedFer Beacon
A PIC16x84 processor may be used to generate a PSK31 or FSK31 signal. This could be used for beacon transmissions (as described here) or they may be used for te...
KA7OEI GPS
A plot showing the paths of the recently-tracked and currently-tracked satellites. The receiver`s location is the "bull`s eye" in the center while the top of th...
School Video conference Infrastructure
The most important part of a school`s CATV-CCTV system, is the process of planning for its infrastructure and the actual plan itself. The schools planning ideal...
TV Decoder
The DE2 board is equipped with an Analog Devices ADV7181 TV decoder chip. The ADV7181 is an integrated video decoder that automatically detects and converts a s...
GPO one-piece telephone
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HOLTEK 9200B & 9170B DTMF Generator & Receiver
The 4 data lines from the Keypad Interface go straight into the data inputs of the Holtek 9200B DTMF Generator (pins 6, 7, 8 & 9), and the Inverted Chip Enable ...
DTMF Decoder 2
This device and all information contained on this website is for educational purposes only. This device must be used in conjunction with any and all local, prov...
DTMF Decoder
This device and all information contained on this website is for educational purposes only. This device must be used in conjunction with any and all local, prov...
GSM Playground PCB Diagram
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LM1881 LM1881 Video Sync Separator
This article briefly describes the NTSC-PAL TV Signal Identifier (LM1881). Although this circuit is very easy to understand, but also very practical. Circuit el...