Looking to spice up your Halloween decorations this year? Learn how to make LED eyes for less than $5 with this beginner electronic project.
This is a fun project that can be completed in an hour. If you have an Arduino starter kit you may already have many of these components, but don’t worry, Arduino is not needed . The end result is a set of battery-powered LED eyes that you can throw at bushes or other objects.
Here’s what they look like in the dark:
What you need
- 2 x 5mm red LEDs ($5.27/50) [ Великобритания ]
- 1 x 27 ohm resistor ($6.16/100)
- 3 x AA batteries
- 1 x SPDT switch ($11.78/20) [ Великобритания ]
- Assorted heat shrink tubing ($6.29/set) [ Великобритания ]
- Assorted 7/0.2 jumper wires ($8.99/set) [ Великобритания ]
Total cost: $44.44. It’s not even close to $5!
Well, the problem with buying electronic components online is that they become very expensive if you only want one or two. It is a much better choice to buy multiple items. These pieces are enough to make 20 sets of eyes for a total of $2.22 each! You also get spare parts for future projects — always a good thing. Be sure to check out these e-learning websites. these learning sites. these learning sites for more design ideas.
tools
You will need some basic tools for this project. You can get by with tape and cable ties, but that won’t make a very secure connection.
- wire cutters
- Pliers
- Wire stripper
- solder sucker
- solder
- soldering iron
- «Helping Hands» (UK)
Don’t worry if you don’t know how to solder, we’ve shown you how to get started. You may already have many of these tools and can do without them all, however this is an easy choice and should be the staple of your toolbox.
Scheme
This is a simple scheme — do not be afraid of this. Three AA batteries connected successively (one by one). This increases the voltage to 4.5V (each AA battery is 1.5V). Parallel connecting the batteries would increase the current — this is not necessary, since the minimum voltage required to light a single LED is about 1.8-2.4 V, which can provide a little more than one battery.
The resistor is needed to limit the current going to the LEDs. Never connect an LED directly to a power source, it will usually burn out. There is a definite formula for calculating the required resistor (although LEDs often tolerate a small difference). This site is great for calculating what you need. If you want to use more LEDs or a different battery setting, enter the following details:
- Supply voltage (in this case 4.5 V from 3 x 1.5 V batteries)
- LED voltage drop — typically between 1.8V and 2.4V
- Required LED Current — Typically 20mA
- Number of connected LEDs
The retail stores where you buy LEDs often list these specifications. click, to calculate, to get the resistor value you need.
Finally, the switch simply turns on and turns off chain. You should not use this, although it will save battery life when not in use.
Link it
First, make sure there are no batteries in the battery holders! It can be dangerous to heat the batteries too much. Solder the battery holders together, moving from red to black to red . You should have a red and black cable (one at each end of your chain) «free» for the rest of the chain.