I have completed the Touchy Feely Lamp project (#13) in the Arduino Projects Book and it all works great, as long as it's connected to my computer via USB cable.
I would like to make this portable. Not for long term use but so I can learn how to do so.
I've been perusing the forum here and it looks like I'd need to use AA's instead of a 9v as the 9v apparently doesn't have enough power.
I've plugged in a 4 AA battery holder and got no response at all.
So I went searching again and it looks like I might have to provide a ground for the arduino board itself. How do I do this?
What do I use as a ground? Does it have to be lead? What household (or readily purchasable) items might work as a ground? This is an indoor project so sinking a rod into the dirt isn't an option. Will aluminum foil work?
Where does the wire from the ground item connect with the arduino Uno itself? On the negative rail? Where does it go in relation to the battery pack wires?
I am a newbie still, just working my way through the project book so I apologize if these are baby step questions.
OK. The takeaway is that Ground is established relatively easy by keeping the sensing pin as a small contact and ground as a much more massive contact - in terms of surface area.
The ground connection on your Arduino is the Gnd pins on the headers which connects to the copper foil on the PC card. If you bring a wire from this connection and attach it to a large surface in the same proximity as the sense pin then when no human is around, both connections have the same "float" potential but when you touch the sense pin your body makes the sense pin effectively include your body.
You can try several configurations, a brass tack in cork for touchwith the Arduino Gnd pin attached to a larger area of aluminum foil on the rear of the corkboard. A rectangular piece of foil connected to Gnd with plastic wrap covering a section where the sense terminal is positioned.
Ground would therefore be something metallic that is physically larger than the touch contact but in very close vacinity to the sense contact. Sense being a wire leading to the Arduino pin and Ground being a wire connected to the larger piece of metal and connected to Gnd on the Arduino.
In some cases, there is not even a need to carry the ground from the Gnd pin of the Arduino external. Lots depends on the environment and the power supply powering the Arduino, etc. Just know that it is possible to design so that ground is simply relative to a neutral charge... almost always, this is where we can secure access to the power company's reference.
Depending on wire length and connection quality, you may have to physically bridge the ground object and the touch wire with your body... Like holding a small cork board with an aluminum frame connected to Gnd. Your hand holds the frame and a finger on the other hand touches the sense contact. When all works as hoped we only need to touch the sense contact.
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