Diode question

[problemman]

I am that familiar with electronics so was hoping on some help. I have one contact closure (discreet alarm) and need to drive two separate interfaces (one at 24VDC and other one on 48VDC). I will be using back to back diodes. Previous I have seen them use 1N4003 diodes which are rated at 1amp. I know that I will drive double ckts and wanted to use 2amp rated diode and preferably not too big in size. Does anyone know if I can use diode #2A03
Thanks

 

[MikeMl]

The diode ratings depend the current flowing through them, and the reverse voltage they will be subjected to. If the contact closure completes a path to ground to turn on both the 24V and 48V circuits, then the reverse voltage across the diode in-series with 24V load will subjected to 48-24-0.7V = ~23V, so even a 1N4001 would work.

Each diode only passes the respective current it takes to turn on its own load (not the sum of the two currents).

 

[problemman]

Thanks. The 2A03 (or 2A01) has a Average rectified output current of 2amp (versus 1amp for the 1N400x diode). The contact closure will complete a path to ground. And I wondering if with the 2amp rated diode, can I switch twice as large load with it?

Thanks

 

[MikeMl]

Depends first on what the relay can switch? Second on what kind of load? Resistive vs Inductive?

 

[problemman]

I think that it would be a resistive load. Is the 2amp Average rectified output current rating able to continuosly drive a 2amp DC resistive load? Or does this need to be prorated because of DC or something else?

 

[MikeMl]

It needs to be prorated to ambient temperature. For a pure DC Load, the average is the same as the actual current...