How to wire 4 of the same 12volt devices to a single on/off switch

[Joseph Parkhurst]

I have 4-12volt devices that draw 11 watts each at what I calculated to be 0.91amps each. I want to wire these to a single on/off switch. Would a 12volt/4amp power supply be sufficient and would I wire them in series or parallel or combination. Also, could I just connect them to my PC's PSU 12 volt rails after the on/off switch instead?

 

[clutchc]

It's going to depend on what the devices are. For instance, if they are motors (i.e. fans) you will want to allow for starting (locked rotor) current. A larger PSU than their total wattage will be required. And they need to be wired in parallel.
If the devices require 12V, you will want to wire them in parallel. Series wiring will divide the voltage between them depending on their impedance.

 

[Joseph Parkhurst]

It's going to depend on what the devices are. For instance, if they are motors (i.e. fans) you will want to allow for starting (locked rotor) current. A larger PSU than their total wattage will be required. And they need to be wired in parallel.
If the devices require 12V, you will want to wire them in parallel. Series wiring will divide the voltage between them depending on their impedance.

Thank you Clutchc for the fast reply. The devices I'm using are small VFD Spectrum analyzers. I assumed I would wire them all in parallel but wanted to confirm 1st. I'm also assuming there wouldn't be much more amps, beyond the rated, drawn from such a device. The power supply I was looking at are 12v,4amp,48watts. that's 4 more watts than the total of 44watts from 4-11watt devices. Should I go larger? Thank you in advance for any help

 

[clutchc]

It may depend on the PSU that you are using. (1) Most have an 80% efficiency rating, meaning that beyond that they are less stable and cost more to operate. (2) Not all PSUs' total wattage is rated as continuous*. (3) Where are you finding a PC PSU that is only 48W? Or is that just the rating for the +12V rail?

*Cheap PSUs usually use their peak wattage as their "total" wattage. Either way, you will be cutting it close.

 

[Alabalcho]

Computer power supplys are not that happy when you (over)load one rail only. Go to place like this one, and get fixed-voltage 12VDC power block, rated for like 6/8 amps (so you have some reserve).