telephone ringer project

Posted on Feb 6, 2014

Make two telephones ring onstage. This involves sending a signal down a line to the phones. I was hoping to find an old telephone exchange system, but no luck yet. I have found a few ideas for circuits, but would ideally like to make a ringer output that is realistic. This would be about 70-80v at 25Hz. I cannot find any way to make a basic analogue frequency divider, so wonder whether my best bet

telephone ringer project
Click here to download the full size of the above Circuit.

is as follows: We used to use subcycle  transformers to generate 30 hz from the 60hz power line. It is basically an LC tuned winding of a transformer. Personally, I think it is easier to just use the power line frequency. Frequency selective ringers for use on party lines (don`t have many of them anymore) operate from 20 hz to 60 hz. No matter which frequency is used with the old two-bell ringers, the tone is going to be the same and I cannot tell the difference between a bell tapping at 60 hz from one operating at 20 hz. Note that the ringer is strictly AC and is blocked from the 48 volt DC talk battery by 0. 1 fd 200 volt capacitor in the telephone`s network. A proper phone ring doesn`t cut off in the same way as an MP3 file. If someone picks up an old bell phone there`s a distinctive "ding" from the handset as it finishes ringing, an echo. If you hear them both you`ll realise the MP3 doesn`t sound quite authentic because of this. By the time you`ve set up the system to work the echo onto the end of the file then also make sure it`s ringing in stereo and sounds as though it`s coming from the stage it makes sense to just make the things ring. FYI: In the US the ringing cycle is 2 seconds on and 4 seconds off. Ringback tone (what the calling party hears) is 1 second on and 3 seconds off. If burst ringing is enabled the first ring can be as short as one second to as long as 3 seconds. The Central Office puts one second of...

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