Intro: UV LED Torch
In this tutorial, I will show you how to construct a simple, cheap, and powerful Ultra-Violet Torch for all your UV illumination needs. This project is beginner friendly and requires only basic soldering skills.
Lets get started!
Step 1: What You Will Need
Components you will need for this project include:
- x2 Ultra-Violet LED's. (I purchased mine from Radio Shack for under 2 bucks.)
- x1 100-Ohm Resistor (Again, from Radio Shack. 99cents for a pack of 5.)
- x1 DEAD 9v Battery (or purchased 9v battery clip)
- x1 WORKING 9v Battery
- Basic Soldering Equipment.
Step 2: Extracting the 9v Terminal Clip
Using your pliers, Carefully peel the shell of the 9v back, and expose the cells inside the protective covering. In this step, we are going to extract the terminal clip, which will be the base of our project.
Step 3: Warm Up the Soldering Iron- Construction Begins
The first part of this step includes determining the Negative (-) contact on our freshly extracted clip. When dealing with 9v batteries, the large contact is Negative, and the small contact is Positive. But beings that the terminal clip is going to connect to our working 9v battery, the contacts for the clip we extracted are reversed. The small contact connects into the large contact, and vise versa. Identify the Negative (-) contact on the clip we have just extracted (the small contact of the two) and begin soldering the 100-Ohm Resistor to its corresponding contact point on the back, trimming the resistors leads as needed. Refer to Picture.
-Note: Be generous with the amount of solder to get the resistors lead firmly connected. I had a hard time getting it to stick well with minimal solder. Adding more will do the trick.
Once the Resistor is secured, bend it downward also bending the un-soldered lead parallel to the resistor. This keeps the circuit organized and compact.
Step 4: Soldering the LED's
Once you've determined the Negative terminal and have firmly soldered the resistor to the contact, and bent the resistor in a organized manner, we will now start soldering the LED's.
First, with one LED, trim the POSITIVE (+) lead to about 1/4"
Next, with the other LED, trim the NEGATIVE (-) lead to 1/4" as well.
Once you have done this, you'll want to bend the shortened contacts both outwards at a 90� angle.
Last, solder the two shortened contacts together.
Refer to Picture
Step 5: Putting It All Together
Once your LED's are soldered together, and your resistor is soldered and bent strategically, you may now trim the un-soldered LED leads and solder them to their correct terminals. The LED with the un-soldered NEGATIVE terminal is soldered to the un-soldered resistor lead. The LED with the un-soldered POSITIVE lead is soldered directly to the positive contact, or the "big" contact corresponding on the opposite side.
-Note: If you look carefully into an LED, connected to the leads are two pieces of metal. One piece is significantly bigger than the other, that lead would be NEGATIVE (-). Leaving the smaller piece POSITIVE (+).
Step 6: Let There Be Light!
Your finished project should look something like the picture below, and easily clip onto a working 9v battery for a powerful, long lasting UV LED!
If UV isnt your taste, you can duplicate this same project using different colored LED's, but that would require a different resistor suitable for your LED.
How do you find out which resistor is right for the LED you want to use?
When buying LED's, specifications are usually given for the average operating voltage, and mA to illuminate the LED. With those values, you can plug them into a simple online calculator that will give you the best resistor for your needs. This calculator can be found here: http://led.linear1.org/led.wiz
Question: "I have 2 LED's, but they are salvaged, therefor I don't know their operating values to plug into the online calculator."
Answer: A good rule of thumb is not to run a LED on any more than 3v WITHOUT A RESISTOR unless specified to have a higher operating range. For LED's with unknown voltage and mA values, "diode forward" or operation voltage should be 3, and 20mA should work just fine.