Classic Rotary Phones Forum

Telephone Switching => Key Systems (Electronic, 1A2 etc) => Electro-Mehanical Key Systems (1A1, 1A2 etc) => Topic started by: Babybearjs on December 07, 2022, 07:10:34 PM

Title: will any diode do?
Post by: Babybearjs on December 07, 2022, 07:10:34 PM
I'm in the process of setting up diode ringing and need to know what diode is supposed to be used? will any diode work? or are they like resistors, and have certain values that need to be followed. I understand that I need to bypass the capacitor in the phones as the diode replaces that function. any help is appreciated....
Title: Re: will any diode do?
Post by: countryman on December 09, 2022, 02:18:05 AM
I have no clue about diode ringing  ;) but  a diode is a "valve" that lets electrons pass only in one direction.
What you normally get today are silicon diodes, which are quite robust. They are classified by the current capacity in forward direction and the allowed inverse voltage. In the forward direction there will be a voltage drop of 0.6 or 0.7 Volts. This is a material property of silicon.
A very common type would be 1N4007 for 1 A and 1000 V, but many many other suitable types exist.
Formerly, selenium rectifiers were often used in telephone and radio applications, but they are no longer made. They are doing basically the same job but the characteristic curve is different, the forward voltage drop starts around 0.4 V but rises over 1 V when the current increases, heating up the element more.
Title: Re: will any diode do?
Post by: dsk on December 09, 2022, 05:29:46 AM
Does this film help: https://www.youtube.com/watch?v=03Gvk6mm13Y
Title: Re: will any diode do?
Post by: Babybearjs on December 11, 2022, 12:35:54 AM
yeah, I looked at phils video about it already.. quick question is, does this work on regular land lines, or is the diode ringing dedicated to ringing voltage from the PSU only.... I have 3 landlines coming in and 10 extentions I'd like to setup on this system if it can be done....
Title: Re: will any diode do?
Post by: dsk on December 11, 2022, 05:30:34 AM
I don't know, some exchanges does allow you to use a diode instead of the capacitor, but none of mine.

Whats happening if you need a common ground for the ringers is even more complicated so that will probably need a lot of thinking before you are finished ;)
Title: Re: will any diode do?
Post by: Stubbypylon on December 18, 2022, 04:24:34 PM
These should work - 1N4005 also a 446F was  used back in the day.
Title: Re: will any diode do?
Post by: payphone2830 on January 28, 2023, 08:02:33 PM
One trick that you can do is add a one diode to one of the buzzer pairs in the phone. This will make the sound of the buzzer different and sound like a burp.