Hi,
I'm trying to connect the grounds of all my devices together. I have 9 12V solenoids (max 3 working at the same time), some atmospheric sensors, an SD card reader, RTC, things like that (tell me if I need to list all of them or their current draw). I have the classic cheap little breadboard, could I connect all grounds to the (-) strip on the side? Thanks
Peter
Could be too much current for a breadboard with those solenoids - can they be wired separately with
a single ground connection to the breadboard? You'll have to consider interference from the solenoid
circuitry too, best to keep away from sensitive sensors and the RTC.
Powering one solenoid through a plug-in breadboard is probably "pushing it". You might think about another wiring method for the "high-current" parts of the circuit.
I see, I can find another solution. Thanks a lot!
Hi,
You need to think about "Common Ground Point..."
Especially with high-power devices it's often best to decide the negative terminal of the larger power supply feeding the solenoids or other high-power devices is the "Common Ground Point".
See the info and discussion about this here:
https://arduinoinfo.mywikis.net/wiki/Arduino-Project-Planning-Electrical
Example section:
---------------------( COPY )---------------------
Wither Ground.. What IS Ground?
Ground is a (hopefully single) point that everything electrical is referenced to. When my house was built an 8 foot long copper-coated rod was hammered into the Soil (Ground) and a heavy wire was run inside to become the "Grounding Conductor" for all my house wiring. Your house or apartment or high-rise has a Ground Connection like that somewhere down below. If you have a car or truck, the point where the cable from the negative terminal of the battery is connected to the frame or engine block is "Ground".
Common Ground Point: This is a connection point you create on purpose to help avoid interference problems between different devices.
Current from high power devices like motors that are connected directly to Arduino ground can cause the Arduino ground terminal to "bounce around" compared to other devices like sensors. This is called "Ground Bounce" and it can cause errors. By running separate ground wires from Arduino and other devices to a Common Ground Point they do not affect each other.
Usually the best Common Ground Point is the negative terminal of the high-powered device's power supply.
If your project is housed in a metal chassis or box a good approach is to place a long bolt (perhaps 10-32 or M5 size) in a hole in the metal chassis. Then several different ground wires can all connect at that point, usually with round lugs that fit on the one bolt. A short, heavy wire runs to that point from the negative terminal of all power supplies. If the project has incoming 120V or 240V power, the "Green Ground" of the incoming power cable also goes to the common ground point. That goes back to the building Grounding Conductor which is connected to Earth Ground.
-----------------( END COPY )----------------------
Let us know what you do and how it works out...
And I would still need to connect the ground to arduino, right? I'm powering the solenoids with a power supply and controlling via transistors, so what I do is wire all transistor emitters to a common ground connected to the neutral from the power supply and then wire the ground to arduino? Will it not damage the arduino?
Neutral? Are you mixing AC and DC here? That sounds like a bad idea.
Normally if it's all DC you connect the grounds together - as in the negative poles of the various power supplies in use.
If you mean mains neutral, no no no NO!
Perhaps you meant the negative DC output from the supply?
No no, that's what I meant, I got it.Thanks