Connect the LEDs to an on/off switch
About this video
The presenter wires the LED eyes of a spout bot through a sliding single-pull, double-throw switch. He loops the white wire around a free switch contact and crimps it tight, bends away the unused terminal, then ties the resistor leads to the negative battery wire. He stresses checking every connection with the LEDs before hot gluing, and insulating the exposed twist with electrical tape.
You'll be able to
- wire an LED circuit through a single-pull, double-throw switch.
- secure a wire loop to a switch terminal without creating a short.
- test a circuit before permanently sealing it with hot glue.
Key words
- Single-pull, double-throw switch
- A switch with one input contact that can be routed to either of two output contacts.
- Terminal
- A metal contact point on a switch or component where a wire is attached.
- Crimp
- To press a wire loop tightly around a terminal with pliers so the connection holds.
- Short circuit
- An unintended connection between two conductors that bypasses the part of the circuit meant to do work.
Transcript
All right. So we're almost there. Now, what we're going to do is we're going to wire our LEDs, so our eyes, so that they light up. And we're going to use the other sliding single-pull, double-throw switch to do that. So we're going to take our needle nose, and again, we'll put a little loop in the white wire that we had remaining from our previous that we made earlier in the videos.
And we're going to loop that around one of our remaining contacts on our single-pull, double-throw switch. And again, it's a little tricky. You want to make sure that you get a pretty tight loop. And then, you'll push it around that contact. And once you've got it on there, you can take your needle-nose pliers and just make sure that it's crimped tightly against the terminal that's exposed from the switch there.
And again, you want to make sure that it's not touching any of the other terminals. So if it is, the switch will always stay on, and it won't work properly. I'm just twisting it very tightly here to make sure that it's very firmly connected. So now what we need to do is we need to connect another wire to our resistor leads from our LEDs that we created earlier in the previous videos.
And I'm going to go ahead and bend this other terminal on the switch out of the way that we don't need. And again, that's the one that's on the far side of the sliding switch there. So now we have our wire from our battery, which is our negative wire. And we're going to connect back to our resistors.
And we're just stripping off a little piece of-- we're using the white wire again. We're going to strip off a little piece of the white wire there. And again, we'll take off about a quarter of an inch on both sides, and 3/8 of an inch will work too. Generally speaking, if you take just a little bit more insulation off, it's a little easier because you have a little bit more wire to loop around.
But it also means that you have more that you have to cover up once you're done. It's kind of tricky, but a quarter of an inch works for me. In any case, you can just use the wire strippers there and pull the wire. If you wiggle it around a little bit, it'll come out and strip off the wire there.
And again, we're going to take our needle-nose pliers, and we're going to loop these around and create the loop to go over the terminal there. Once we have the loop done, we'll use our needle-nose pliers to crimp it in place. OK. So once it's crimped in place, we can hot glue it.
And one of the things I should have done is I should have tested to make sure these contacts were in fact tightly connected before I hot glued it. But I was pretty sure they were, so I went ahead and hot glued it in the interest of time. But when you're making this, you're going to want to test that switch.
And you can use the LEDs there to make sure that everything is connected properly before you hot glue it. Because again, if it's not, it's more of a pain to take the hot glue out and redo everything. OK. So now we're going to connect our LEDs to the remaining wire that we have on our switch.
And that's going to allow us to complete the circuit and turn on the eyes of our spout bot. So we can take the two leads from our resistors and touch them there, and make sure that all the power is flowing how it should be. And so you can see how the switch will allow us to turn that on and off.
And so we're going to twist those resistor leads together. And then, we're going to wrap them around the white wire-- the exposed part of the white wire. And that'll allow us to complete the circuit and light up the LED lights, or the eyes of our spout bot. OK.
So once the eyes have been connected and the wires are twisted together, we want to make sure they're twisted very tightly together. We'll make sure the wires that are exposed are separated, so they don't short. And then, we're going to turn the switch on and off and see if our eyes light up.
And they do. So we cut a little piece of electrical tape, about a half of an inch square. And we're going to use that electrical tape to basically cover over the exposed wire that we just twisted together, to ensure that it stays connected and that it's insulated.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.