The principle of the offline phone tester

2016-01-29 20:58  
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This article describes an off-line telephone tester works. The principle is simple there, we recommend that combine text carefully read the complete schematic. Figure: 1. Connect the telephone terminal signs "to call in the test and switching power supplies (switch S1). 2. To test the collar portion, flip switch S2 position 'B' and press S3 for a while and you should hear the bell, bell circuit testing to prevent the phone is working, please ensure that the phone is in the cradle of the test. 3 is used to test the audio portion, flip switch S1 'C' position and connected to the headphone socket SK1. answered the phone handset, when it comes to its microphone. If the audio part is working satisfactorily, you should be able to hear your speech through headphones, if you dial a number, you should be able to hear the pulse clicks or pulse tone headphones, depending on the phone functions under test in the pulse or tone mode If the phone under test has a built-in music device occupies, press the "Save" button, you should be able to hear the music. now flip switch S2 position 'A'. you should be able to hear the music through headphones phones generated IC1 telephone under test, indicating propor audio amplifier section features this circuit can be assembled on a small piece of veroboard. attempt to install both sides of the  transformer  board, displaced 90 degrees. always kept testing more convenient modular plug type all types of phones. mount all switches, sockets, led in front of the test panels in order to better grasp this principle, it is recommended to read several times on this principle.

Off line Telephone tester

Off line Telephone tester

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