breadboardground
I need to connect an input signal from a function generator to a circuit I made on a breadboard.
If I use a BNC to Banana cable, then would the "ground" of the function generator (the ground on the banana clip) be the ground for the entire circuit?
I suppose my question is, is the ground voltage just something I choose so long as I keep it consistent, or is there a literal ground on the breadboard somewhere?
The breadboard looks like this:
It is a pretty low parts count design, but it is by no means simple. It helps to understand how the chip works inside to see what pins are more sensitive to stray EMI than others before doing a layout. Then you can determine where coupling to ground is useful and when it can interfere. ( This is just learning curve info not specific to your layout) Although many students use the physical layout approach, it defies logic and when you want to understand how it works, you need to use logic in your schematics not just physical layout. This is most useful when it doesn't work.
vs
When you discover the load regulation is poor due to the layout of the external transformer in relation to RFB feedback, which schematic will you follow and how will you discover why it fails in your layout. Unfortunately what schematics do not show is the equivalent circuit of a ground plane and its coupling. This is why a more "Logical" schematic is important and rules for small inductive loops is important and coupling to ground planes. Although I concur with your aadvice given, this design will be very noisy and suffer in regulation becuase of how the boundary mode processing works inside the chip. A more reliable design will use large voltage feedback thru a tertiary winding (which they use in msome aqpplications)
It may work, but how well is the question.
EMI radiation, Load regulation, Step response and ripple are important measures of performance which are affected by this clever chip's internal processing of the current waveform using the MOSFET resistance. When it fails you can try to understand how it works. With your schematic, all you can do is see that the parts are connected to the right pin.
These basics although may seem tedius to you, they are critical to getting the perfromance offered by the chip. Layout is critical in this design because of the simplified external feedback of transient switching. I would use a small planar SMD torroidal transformer such as the one used by Linear Technology and follow their layout guidelines.
Simply connect the breadboard/wallwart ground to the Arduino ground. As long as you don't connect the wall-wart positive to the Arduino, there should be no problems.
Best Answer
There are four common types of ground:
Realistically, all of these grounds are the same, but they are usually kept separate for the most part, only being connected together in a single place to avoid loops, and often using an inductor.
To connect any two circuits together, they have to share a ground connection. While this does not always mean "earth" ground (such as battery operated devices) it does mean a common node for the voltage return. In the case of a function generator, there are two connections from the device: signal and ground return. The signal will have your "function" being generated such as a sine wave. The ground connection is necessary to complete the circuit. Without it, no current can flow.
As far as connecting it to a bread board, there is no specified ground connection. Any pin could serve as ground. Often, there will be a common column of female headers to be used as a power or ground rail. In your bread board, there are four of them in the very center. You need to connect the ground of the function generator (the black plug, or the outer shell of the BNC) to the common node (ground) of your circuit.
Ground is not a "voltage" but a reference to the level of voltage. The voltage level of ground is said to be 0, so all other voltages are measured with ground (0V) as the reference level. Some circuits use "virtual grounds" which can be levels other than 0V, but that is a bit more complex.