OK! I need the help of you electronic guys again. As I said in an earlier post I received an Antec Basiq 350 ATX switching power supply for Christmas and received some helpful info about the chassis ground with the power supply commons.
What I didn`t ask was if I could join up the 2 +12 volt rails and take all the + leads coming from these two rails and join them together under 1 terminal post. I cut off all the connectors and have 6 wires coming from these 2 rails that are +12 volts.
How about all the commons from the 2 12volt rails, the 3.3volt rail and the 5 volt rail? Also the commons from the -12volts and the +12 volts SB. In other words can I join all the black wires under 1 terminal post also?
Thanks
Bob D As long as you surface as many times as you dive you`ll be alive to read these posts.
Why do you want to do that? All of the black ground wires can be connected together, but it doesn't gain you anything because they are all connected to the same ground bus inside the case.
Connecting all the red wires together gains you nothing because they're all connected to the same power transistor inside the supply and just one of them has the full +5 Volts at whatever the max Amp rating for the power supply happens to be. Adding more red wires will not give you more Amperage output and the voltage will not be additive.
Same goes for the yellow +12 Volt wires -- just one gives you the full Amperage output and using more than one connected together will still only be the power supply's rated Amperage.
And don't even think about trying to connect a yellow 12 Volt wire and a red 5 Volt wire together to get 17 Volts -- all you'll get will be a lot of smoke and maybe some schpitzen schparken.
Cacole. I see your point but the wires coming from the ps are of a large gauge (I`m assuming 20 or 22 gauge and to get the full output of 23 amps for the +12 VOlts and 20 amps for the +5 volts I would think that I would have to use more than 1 wire for each of these voltages. I realize that this wire would only be about 5" to the TB but using the logic that we should keep our track feeders to 6" or so to reduce voltage drop wouldn`t the same apply to the ps leads? I wouldnt even think about combining a 12 & 5 volt lead to get 17 volts. I don`t need that voltage anyway and have enough of an electrical knowledge to not even try this.
Do you think you will ever be drawing the full 23 Amps on the 12 Volt output? If you do, then you can use two or three of the yellow wires connected to separate devices or separate circuits instead of connecting them together.
I use a 250 Watt computer power supply on my HO scale home layout for signals and building lights, and we have a 550 Watt computer power supply on our large HO scale club layout, but neither one of those supplies has more than perhaps 70-80 Watts of actual load at any one time.
The Ohms law for DC Power in Watts is expressed as P=EI, or Power in Watts = Voltage times Amperage, so your power supply with a rating of 23 Amps at 12 Volts has a capacity of 276 Watts. It's probably actually rated at 250. And if you also draw 5 Volts for something, the amount of Watts consumed by that output has to be subtracted from the 276 max capacity.
Wire gage is really determined by power or watts, ie basically roughly volts times amps. Your household uses 14 gage for about 1600 watts. You're looking at around 240 watts. So, 20 gage should be more than enough. BTW, for model railroading 20 amps seems like more than normal by a lot. Normally when you're talking that kind of amperage you divide up the PSs to something around max 10 amps to avoid shock/damage issues. Note that all DCC mfgs recommend you have power blocks for extremely large layouts. Most wattage is around 70(5A x 14V) or less for most MRR users. I use a 10A PS for an 8A system, but fused to reduce total wattage allowable to DCC system.
Richard
One thing you do NOT want to do is group all the wires together and make one monster power bus under your layout. 23 amps at 12 volts is a LOT of power, and can cause a lot of damage is something shorts out. Instead run individual lines fused to a more reasonable 2 amps, that way if somethign shorts out only that one line will go down, and the fuse will blow rather than the power supply. There's no need to group 6 or more wires to each terminal, 2 from each voltage is plenty. All the grounds are PROBABLY common - some newer power supplies only provide a single voltage fromt he switching supply and use regulators to get the other voltages, but that model is not one that I think does that.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks Cacole, Randy & Richard again good advice that will be implemented on this power supply. I particularilly like the advice of breaking up the i2 volt (also the 5 volt) into smaller fused circuits.