As a reminder, all of the supply links I provide are just there to help. If you have something on hand, or pick out something cheaper, that is perfectly fine. That said, things you’ll want on hand for this part:
- Your circuit so far
- Some sort of flippy switch
- Your soldering iron
- Some solder
- Wire strippers
Now, this time we will be modifying our circuit by adding this switch. Our new circuit will match the circuit diagram below.
“Wait! But there are TWO circuits!” you cry. Yes, yes there are. If you look at them carefully, the only difference between the two is whether the switch is connected to the battery’s positive or negative terminal. In practice, and for safety with higher voltage and current, you would connect the switch to the battery’s positive terminal, so that you don’t accidentally become the grounding component in your circuit.
However! These are floating ground on a very low power system, so in practice, for our purposes, it does not matter which side you connect your switch to. I will reiterate though: for safety, the best practice is to connect your switch to the positive terminal on your battery.
Now that that is out of the way, you may be wondering why both of these circuits could be treated as being the same. The correct answer is in the picture itself! The image for a switch is an open or closed line of wire (showing it’s default “safe” state). Since the purpose of a switch is to “break the loop” that means that it will break the loop in either position, and since current wont draw to an open end, the LED wont get power, and the circuit will be “off”.
So! On to the practical exercise! First and foremost: Remove your battery. I know that seems obvious, but getting a spark will definitely make you jump, and with larger circuits can be dangerous! Even if your battery has run out of juice, please, please remove it. It’s a good practice to get into.
Once you’ve de-powered your circuit, we’ll move on to incorporating the switch! If you were smart and labeled the positive and negative wires on your circuit, then now is the time to cut the positive wire in the middle. (If you don’t have them labeled, that’s alright! As we just saw, this will work no matter which side you connect, so pick one of your wires and cut it.)
Strip the now open ends and solder them to the leads on your switch like so:
Note: If your switch has three leads instead of two, this means your switch is what’s called an ON-ON switch rather than an ON-OFF switch. This is okay, it just means you will have an unused lead in this situation. Flip the switch to the “on” state you want, and then insert your battery into the holder. Then, just like when we were looking at battery leads, carefully touch each wire end to a different lead until your LED lights up. When the LED lights up, you know you have the correct pair of leads. Label them, then REMOVE THE BATTERY before soldering the wires to the lead pair.
Does it matter which wire you solder to which lead in the pair? Not for this scenario, and not for an ON-OFF switch. It basically functions the same as you physically tapping your wire to the battery when in the ON state, and removing it when in the OFF state. If you have an ON-ON switch like discussed above, and wanted to connect something (say… A different color LED) to that third lead, THEN it would matter which wire is connected to each lead, but that’s beyond the scope of this tutorial.
Once all is said and done, you should have something that looks kinda like this:
Perfect! Stick your battery in and flip the switch to “ON” aaaand…
Ta-da! There is light once more! Be proud of yourself, because you have functionally made a flash light, and honestly? You should be proud! You’ve gone from zero circuit knowledge to building your own flashlight! You’re now armed and dangerous, and from here the sky is the limit!
I will be making a couple more follow-up tutorials of more complex circuits, but consider yourself armed with the basics, and at this point you have all the skills you need to start making a LOT of different electronic projects.
Something Something Tutorials 