Introduction: How to Make an Illuminated LED Eye Loupe

By www.dvgadre.com

I have been using an eye loupe for viewing small electronic components, inspecting PCBs etc. However I was intrigued the other day when I saw this illuminated LED eye loupe at Sparkfun and I thought I should make my own.

The instructable shows how to adapt an ordinary eye loupe to an illuminated LED eye loupe. After I made one, I was surprised at how much better the magnified objects look due to the illumination.



Step 1: Components and Tools

Components:
1. SMD White LEDs PLCC package - 8 numbers
2. SMD Resistors 100 Ohm 1206 or 0805 size: 8 numbers
3. copper clad board (stock PCB), cut an annular shape (see the next step for the dimensions)
4. ordinary eye loupe
5. Battery holder (4xAA battery holder)

Material:
1. Multistrand connecting wire with plastic insulation, 2 colors - 1 feet each
2. Instant glue
3. Solder iron and wire
4. wire cutter



Step 2: Make the PCB

Once you have all the tools and components, the first step is to prepare the PCB to solder the LEDs on.

Measure the diameter of the lens and the diameter of the rim of the loupe. Let A be the diameter of the lens and B the diameter of the rim. The inner diamater (ID) Of the annular PCB should be equal to A and the outer diameter of the annular PCB should be equal to B.

An eagle brd file for our annular PCB can be downloaded from this instructable and used as is or modified for your particular loupe dimensions.

We used a Modela milling machine to cut the PCB, but with a bit of effort and patience, you can actually do it manually with a drill machine and dremel tool to separate the copper in two circular concentric bands.

Step 3: Solder the LEDs and Resistors

Once you have the PCB made,  its time to prepare the LEDs. I had some white SMD LEDs in PLCC package. But the size is not critical. Any size such as 1206 or 0805 would do too. Although a larger LED package is easier to solder. Similarly, for the resistor, a large package is recommended although I used size 0805 since thats what I had and it wasnt quite easy to solder this tiny resistor.

Solder the LED and the resistor at right angles as shown in the photograph. You would need 8 such LED-resistor pairs.

Ensure that the resistor is soldered to the LED Anode. You dont want a mix of pairs with resistors soldered to the LED cathode.

Step 4: Soldering the PCB

Mark out 8 equally spaced positions on the annular PCB and solder the LED-Resistor pair as shown in the photograph. Before attempting to solder the component, it is a good idea to tin the location with solder. This will allow the component to be soldered with a minimum of fuss and without too much heating of the components. Solder all the 8 LED-resistor pairs.

After you solder each pair, test that the LED lights up with the help of a digital multimeter (diode test mode) so you are sure that soldering hasnt damaged the LED.

Step 5: Glue the PCB and Connect the Battery!

Once all the LEDs are soldered,  Glue the soldered PCB (with the LEDs facing away from the loupe) to the lens side of the loupe using instant glue. Take precaution to alighn the PCB carefully. Now, connect the battery to the PCB copper bands. Observe the polarity while soldering the battery to the PCB.

I did not use a switch to turn the LEDs off and honestly it was an oversight. You could place an On/Off switch in series to turn the LEDs off, I just remove a battery from the battery holder to turn it off.

How does the illuminated LED eye loupe fare?

Check it out yourself in the next slide!

Step 6: Raison D'etre!

See the photographs here for yourself, how well the illuminated LED eye loupe works.

I had great fun building it and even more fun using it. I hope you do too, should you decide to make one for yourself.

Thanks to Nehul Malhotra for the PCB job!