Hi.
I designed a circuit, on the left. I then decided to redesign it, and you see the result on the right.
Are these circuits "equivalent" to each other? Are they the same circuit?
The only difference that I can think of is that the one on the left, you can put an ammeter into the horizontal wire in the middle to detect whether there's current flowing.
Richard
Hi there,
Because you have drawn the circuits differently and also in addition to that asked the question about asking the designer of the circuit for permission to change it, the implication is that your intention is to wire it differently than what was normally expected. The short answer then is, "Yes", you do have to ask permission to wire it differently.
That's because there are subtle yet important differences in the way some things are wired. It depends what kind of circuit it is of course as an RF circuit would be different than a pure DC circuit and different than a Power circuit or Control circuit, but in most cases you have to pay attention to how long the wires are and where they are placed and things like that. This is involved in the transition from schematic to a real-life product. Other issues come up such as parasitics.
Most of the time the schematic does not show the wiring details, but sometimes it DOES. This is to put an emphasis on the way the circuit should be wired, even though it is not in great detail.
For one example, if that short center 'wire' in your right-hand side schematic was drawn as a thicker line than the others, that would indicate that that wire should be of larger diameter (heavier gauge wire). This technique would be found in various Power circuit like power supply circuits and the like.
For another example, sometimes you will find several wires that come in at various angles and form a single 'point' where they all connect. That is to put emphasis on the fact that there should be a single point in the real-life layout where all those wires are ONLY connected at that single physical point. This would also be found in Power circuits such as power supplies. The intention circuit wise is to control current flow through the various wires so that the current in one wire does not affect the current in another wire by altering the voltage at some node other than that one single point. Schematic wise, the intent is to put emphasis on the need for this kind of attention to the wiring detail.
Those kinds of drawings are usually also accompanied by a note explaining the importance of such a wiring scheme.
It's interesting to note that a simulator may not show any difference, but if you substitute the parasitic values in for the wires you then can see a huge difference in circuits involving higher currents especially if they are constantly changing.
You can see the difference if in your right-hand side schematic you substitute some arbitrary resistance values in for each wire. The node voltages will change. If they change a lot it could be a big problem. This is a very significant issue in power circuits like in power supplies.
This as all why the short answer I gave was "Yes", you have to ask if the change will be acceptable. Sometimes there are notes that specify how the wiring is to be laid out too though so you don't have to ask any questions. A long time ago when wire wrapped prototype circuits were still being used, we had to lay out the entire wiring plan so the assemblers would be sure to get all the wires (every one of them) in the right place. This was to manage current flows and also noise issues and EMI. That required a completely separate diagram though.