Introduction: 9V IR Detector

This is a great, simple project to make a small and robust 9V IR detector. It can be used to seek out security cameras that use infrared light to "see" or to check if your remote control is still working.

Step 1: What You Need

For this project you will need:
-A 9V battery clip with a flat cover made of plastic
-A 9V battery
-LED (any color although it should be clear in order to see it better)
-330 ohm resistor (orange-orange-brown-gold or silver)
-Infrared Phototransistor
-perf board (see 2nd picture)
-double sided mounting tape
-needlenose pliers
-wire snipper
-dremel or hack saw to cut perf board
-clear epoxy-like glue
-Soldering equipement:
      -soldering iron
      -solder with flux core

A shematic is given in step 12, picture #4.

Step 2: Assembly Part 1

First up is putting the LED in. Bend the leads over and insert it in the perf board like in the picture (note that you should start in the corner to make our application as small as possible)

Step 3: Assembly Part 2

Next, put in the 330 ohm resistor like in the two pictures.

Step 4: Assembly Part 3

The last step is to insert the IR Phototransistor like in the pictures. Pay attention that with this part the long lead faces the negative pole.

Step 5: Soldering

After step 2-4 you'll need to solder the parts to the perf board to make your detector usable.
If you're a first-time solderer, you should watch this video: .
(I didn't make the video, thanks go to CuriousInventor)
After soldering, your project should look like the example in the first picture.
Then, clip off the excess component leads, making sure not to break the solder joints.

Step 6: A Bit More Soldering

To finish off the soldering part, you'll need to connect two soldering pads like in picture 1.
For the bridge you can take a snipped off lead from one of the components. I first bent my lead to put it through
the holefor stabilisation like in picture 2, but you don't have to. The result is all that counts.

Step 7: Cutting

After soldering, you'll need to saw/cut off the excess perf board.
Make sure you leave space for the negative & positive wires that are connected to the battery.

Step 8: Attaching the 9V Battery Clip

Take your hardcover 9V battery clip and cut it's wires to about 1/2 inch (1,4mm) lenth like in the 2nd picture.
Then solder the battery clip to your detector and make sure you get the polarity right!
After soldering your gagdet should look like pictures 3 & 4.
To prepare it for the next step, twist the 9V battery clip so it can be bent under the circuit like in picture nr.1.

Now is a good time to check if your device works. Carefully clip it on a 9V battery.
If you try it out during the day, the LED will be partially on depending on how bright it is where you are.
To be sure that it works point the Phototransistor to the sun/roomlight and put your finger over it.
The LED should get dimmer when your finger is in the way. If nothing works, check out the last step for possible solutions.

Step 9: Using the Mounting Tape

Next up is fastening the circuit to the battery clip, the most efficient way I found is to use double sided mounting tape.
To keep everything in place for the tape to stick and for the next step I used wire to wrap it up.

Step 10: Glue Is the Solution

To ensure the detector's long life, glue is used. Just cover up the circuit (except for the LED and the IR Phototransistor), the border on both sides of the mounting tape and the wires from the battery clip with a thin coating of epoxy glue. Let the glue dry over night.

Step 11: Last Step!

After letting the glue dry take off the wire used to let the mounting tape & glue bond.
If you have problems taking off the wire then you've put too much glue on, but that won't affect the
functionality of your device.

Step 12: You're Done!/Problemfixes&circuit Diagram

If you jumped to this step because you have problems with your devices:
1. Check if your battery has enough juice (the "putting the contacts on the tongue" trick will work)
2. Make sure all the solderconnections are nice & smooth
3. Check if there any shorts in the circuit (solderbridges that shouldn't be there)
4. Check if any leads/wires from the parts or battery connector are broken, sometimes too much stress
    on the parts makes them break.
5. Did you put the LED & Phototransistor in the right way around / did you get the polarity right?
As a help I added a circuit diagram as pic #4.

For all the others:
Fetch a 9V battery and try your IR detector. Clip it on and... you're done! Have fun!

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