K
Ken E
In reply to Bill Sturm:
> I do like the idea of internal power for the I/O, I guess. It is certainly seems simpler to use for many applications. <
I mostly agree, but I go back and forth. You might want to limit the current so you don't pop your backplane or connectors. The power required for output cards is rather huge (even at 100mA per channel) though and you would need some kind of reasonable power budget. Nowadays with 1Watt valves being very common you don't need 250ma per output.
At a minimum, Power supplied through the backplane should have Logic and IO Power separate!!!
> I do not like the idea of a wire duct for a rack enclose, they are way too flimsy. We need a better idea here, IMHO. <
Agreed.
> What about a bracket that holds the cards solidly to the backplane, who needs an enclosure? We could ultimately use a <
Some folks make a card guide that bolts to your backplane. These would have to be relatively cheap to compete with a sheet metal enclosure IMHO. For the 8 slot chassis you would have to be probably under $2 a piece to keep it competitive with cheap card guides and simple sheet metal. I had only really considered this for OEM (and hobby) types of applications where cost was king. For professional life I'd spend the extra $20-$30 and get an enclosed sheet metal box to help prevent stray wire strands and screwdrivers from landing on my boards. This is a personal/professional choice and really there is room for both approaches in the spec as long as the boards stay the same for both.
How would you accomplish board retention with simple card guides bolting to the backplane? This was what stumped me on this idea.
KEJR
> I do like the idea of internal power for the I/O, I guess. It is certainly seems simpler to use for many applications. <
I mostly agree, but I go back and forth. You might want to limit the current so you don't pop your backplane or connectors. The power required for output cards is rather huge (even at 100mA per channel) though and you would need some kind of reasonable power budget. Nowadays with 1Watt valves being very common you don't need 250ma per output.
At a minimum, Power supplied through the backplane should have Logic and IO Power separate!!!
> I do not like the idea of a wire duct for a rack enclose, they are way too flimsy. We need a better idea here, IMHO. <
Agreed.
> What about a bracket that holds the cards solidly to the backplane, who needs an enclosure? We could ultimately use a <
Some folks make a card guide that bolts to your backplane. These would have to be relatively cheap to compete with a sheet metal enclosure IMHO. For the 8 slot chassis you would have to be probably under $2 a piece to keep it competitive with cheap card guides and simple sheet metal. I had only really considered this for OEM (and hobby) types of applications where cost was king. For professional life I'd spend the extra $20-$30 and get an enclosed sheet metal box to help prevent stray wire strands and screwdrivers from landing on my boards. This is a personal/professional choice and really there is room for both approaches in the spec as long as the boards stay the same for both.
How would you accomplish board retention with simple card guides bolting to the backplane? This was what stumped me on this idea.
KEJR