Maker Pro
Maker Pro

Where there's smoke...

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
In electronics we do not use pictures, we use schematics. Here:

upload_2017-1-20_22-26-8.png
Bob
 

davenn

Moderator
Sep 5, 2009
14,254
Joined
Sep 5, 2009
Messages
14,254
Are schematics normally drawn with open circuits and no positive or negative indicator?

in Bob's schematic, the POWER is positive, the ground (triangle) symbol is negative

his circuit shows you that the positive and negative line ring wires are unbroken
but that the resistor and the LED are in series with each other and are mounted
BETWEEN the two ring wires

Your photo with your drawn in resistors ( red rectangles) show the resistors in series
with the ring wire and as Bob said, they are breaking up the continuity of that wire
 

davenn

Moderator
Sep 5, 2009
14,254
Joined
Sep 5, 2009
Messages
14,254
Are schematics normally drawn with open circuits and no positive or negative indicator? I'm a novice and I'm trying to learn, I'm not sure how this would help me

Did you understand that ?
or do I draw a pic ?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
I think Dave was just offering to draw a picture of what he said in words to explain in pictures.

In many respects schematics are just stylised pictures. They follow a set of conventions which allow information to be presented in a clear and unambiguous manner.

Unfortunately that convention, if not understood (and perhaps many of us don't even remember when we didn't) means the schematic can be just a collection of carefully drawn, but meaningless squiggles.

In particular, you have identified the drawing of the power supply (or more correctly, the convention of NOT drawing it) as something that is confusing.

I have been very busy for the last few days, and haven't had the time to respond until after others. The problem that has arisen, I think, if a misunderstanding of a request by us for you to place the resistors in series with the LEDs, which are then wired in parallel. As people who have done this forever, the phrase rolls off the tongue, but the concepts are among those that confuse beginners.

Alas, I am answering this on my phone whilst in bed (again), and I have to be somewhere shortly, so I can't draw you pictures. I will try to draw them in your mind...

"Parallel" and "series" are usually applied to elements with 2 connections, or if there are more than 2, we can refer to just 2 of them.

In your case, the LEDs have 2 connections, and so do the resistors.

"Parallel" means that when drawn in schematic form, the elements are in parallel, and will appear somewhat akin to rungs on a ladder, with the connections between them as the uprights of the ladder.

In your case the LEDs have been wired in parallel. Whilst your construction is circular, you could possibly either imagine a small person holding your supply wires and using the LEDs as rungs to climb around your ring light. You could probably also imagine your ring cut at some point and (assuming the wires were elastic) the circle straightened out to become a straight ladder.

"Series" is like taking all those rungs of a ladder and making a tightrope with them. The electrical connections are now the attachment points at the ends of the rope.

Do what we suggest you need to do is to connect each LED in series with a single resistor. That means that one end of the LED is connected to one end of a resistor.

You will now have 20 compound elements, which have 2 free connections, one being the disconnected end of the LED, the other being the disconnected end of the resistor.

What you need to do now is to connect them in parallel, with each of the compound elements acting as rungs in your new ladder.

Practically speaking, this means removing one of your power supply rings (say the outer one) and connecting a single end of a single resistor to the now disconnected end of each LED. The next step is to make another (in this case probably larger) ring of wire to connect all the free ends of the resistors together.

Electrically, it doesn't matter which side you place the resistor. You don't even have to be consistent with the side the resistor is placed. Again, practically, it would be far easier for you to place them all on one side because you've put a lot of work into those rings, and removing both would make the job twice the size.

One thing you'll need to consider is that the wires on the resistors will not provide the same level of support to the power supply ring as the more rigid LED connections. You will probably need to add some form of insulated support for the new ring.
 
  • Like
Reactions: Ian
Top