I have many nodes.

Each node consists of an MPU9250 and ESP32. Each node functions independently. They don't interact with each other.

How can I power all of them at the same time, and switch them all on / off at the same time easily ?

  • Do they have a common power source?
    – Majenko
    Aug 13 '19 at 10:14
  • @Majenko Right now they all have their own batteries. I have no electronic engineering background, so not sure how to get started in figuring out how to power all of them from the same source. Aug 13 '19 at 10:15
  • If they're not on a common power supply, and they don't communicate with each other, there's no way you can control them all together. Especially not for turning them on. To power them all from the same source, just connect them all to that source. Then you have one power switch at the source to turn them all on and off.
    – Majenko
    Aug 13 '19 at 11:15
  • @Majenko that’s the design problem. If you connect them all to the same power source won’t they all draw more power? So won’t you have to design some kind of circuit to ensure they all get the same amount of power or something... Aug 13 '19 at 11:17
  • No, that's not how it works. A device only draws the power it needs. As long as the power supply can provide at least the total amount of power for all the devices together, that's fine.
    – Majenko
    Aug 13 '19 at 11:19

You need to provide more details. How many is "many"? How far apart are they physically? Can you run wires between them? Could you use radio control?

You said in the comments that they are each powered by separate batteries.

One possibility would be to put a power MOSFET transistor on each battery, switching the power supply for a given node. Then wire the gates (and grounds) all together and control them with a switch connected to the supply from one of your batteries (or from a 5V logic line.) MOSFETs draw almost no power at idle, and draw very little gate current for switching, so you should be able to drive dozens of them from a single 5V control line. However, this would require that you have a wire running from a central switch to every node, as well as a common ground to all of them.

  • Not more than six feet between any node. About 30 nodes. I can run wires between them. I don’t know what you mean by radio control. This is all new to me. I’m a software dude, so just trying my hand at surgery for fun. I don’t actually know much about the liver, spleen or what the pancreas does.... 😆 Any tips or guidebook I could read really fast? Aug 13 '19 at 15:22
  • There's a lot to learn. It sounds like you're fairly new to electronics and electrical circuits, so you need to learn the basics of voltage and current, power supplies, voltage regulation, and analog circuits. Then you should probably read up on CMOS, since most modern computers including Arduinos are mostly CMOS. Then you should learn about microcontrollers in general, and Arduinos and their quirks in particular.
    – Duncan C
    Aug 13 '19 at 17:13
  • That’s seems like a lot. I’m just going to hook up wires and see what happens. 👍😊 Aug 13 '19 at 17:20
  • Consider what you have to learn in order to develop software. You need the basics of programming, (data types, flow control instructions, etc) OO concepts, data structures, and algorithms. Then you need to learn the OS and application framework(s) for your target platform, and one or more programming languages. Electronics and microcontrollers are similarly complex.
    – Duncan C
    Aug 13 '19 at 17:38
  • Dude I’m like the obi wan of programming... I bet I could lern lectronixs super fast if I had a tutor.... Aug 13 '19 at 17:41

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