cspan wrote: ↑
Sun Apr 15, 2018 1:19 pm
Thanks for your quick reply! Although my understanding of electronics/electricity is low, I don't think there's any DC part of the power supply in my case. Isn't a DC source typically a battery? My current setup is:
Wall AC Power ==> multi-outlet power strip ==> On/off switch (pictured above) ==> Canakit 2.5A power supply ==> RPi3B+.
Wondered if those two switches between the wall socket power and the Pi would result in too much voltage drop. My Q was, would I be better off with:
Wall AC Power ==> On/off switch ==> Canakit 2.5A power supply ==> RPi3B+.
Which though still having a switch would obviate the need to regularly unplug/replug the Canakit power supply if I simply had this arrangement:
Wall AC Power ==> Canakit 2.5A power supply ==> RPi3B+.
Remember the things like the Canakit supply were originally called "battery eliminators". They convert mains AC to low voltage DC. The wire out of the power supply carries DC at 5V. Everything on the mains side is AC at 120V (at least in USA/Canada).
The voltage drop is proportional to the current. Current (supplying a given load, in this case your Pi) is inversely proportional to voltage. So a voltage drop on the 5V 2A line will be possibly 0.25V, which is significany for a 5V supply. The same switch (if it was safe foer mains voltage) at 120V would have proportionately a much lower current and thererefore voltage drop, around 0.01V. That is totally irrelevant on a 120V supply. (I've kept things simple here, there are other factors, but the conclusion is valid.) So switches on the mains side are fine, switches on the 5V line are a potential problem -- they need to be of very good quality to avoid to much voltage drop.