LED and IR Remote Tester Using Recycled Parts,Hot Glue and Sticky Double Sided Foam Tape

Hi everyone , I decided to create this Instructables having first created a proof of concept so I could try out my ideas and create something useful. I had a few goals that I set to help with this process.

1. No batteries. Not only do these cost money to replace they are difficult to recycle and when they leak it can often destroy the item they once powered.

2. To recycle a plastic throw away container that would probably not get recycled

3. To recycle electronic components that would probably end up in landfill

4. To use double sided tape and hot glue with no fasteners (Nuts , bolts, screws or rivets)

I think I have met these goals, and the resulting device is very useful and because it never needs batteries it will give many years of cost free service and always be ready to use. The best part is that most if not all of it came from items that are no longer useful and would be thrown in the trash.

There was another goal that I did not include in my list, and that was to use the minimum of bought components to build it. But I can see that this depends on the resources of the individual and there is as I found one 'critical'component. The solar cell. But more on that later. I can't say that the basic idea of using the energy from the piezoelectric element to flash an LED is original, but perhaps the idea of using it to do something useful is.

I found hot glue and double sided foam tape to e a great way to make something from soft plastic containers and shall use these methods again in future projects.

1. A suitable plastic container, I found that a mints container that is used by a famous manufacturer that is well known in most countries. These are generally made of a soft plastic that cuts and drills easily and has a pop off top. It only needs to be big enough to fit every thing in.

2. A red LED preferably a high brightness clear type. But pretty much any LED should work regardless of color. The LED I used in the final version was a clear yellow one and it worked well.

The size isn't critical either 5mm or 3mm will be fine, so whatever you have to hand.

3. A holder for the LED: the size will depend on the diameter of your LED, mine is 5mm so I used a 5mm holder. This is of the type that pushes through a pre-drilled round hole.

4. A small solar cell, I had mine in stock and I am including the DIGI-KEY part numbers KXOB25-12X1F-TR (lowest cost) or better still SM141K04LV (Higher cost but much better output voltage - so louder) as these work well. These are as of this week current part numbers available at Digikey. There is a more detailed explanation of this part and why I did this in the construction details.

5. Hot glue gun and self adhesive foam tape (double sided).

6. A slide, rocker or toggle switch, It needs to be single pole double throw (SPDT) or Double pole double throw (DPDT). Whatever type you have will be OK provided its contacts meet these specs a two pole on/off switch won't work it needs to have 3 or 6 contacts. it basically needs to have change over contacts.

7. Hook up wire as needed this can come from a scraped electronic device the exact color or colors is/are not important. I needed very little as my piezoelectric element came with wires attached, so only the solar cell needed wires adding.

8. Double sided sticky tape and double sided sticky foam tape.

9. Clear flexible plastic to make a small window in the container.

10. A small signal diode 1N4148 etc type not critical. But it must not be a Zener diode or Diac as these will not work in this application. If the diode has a part mark you can google it to find out what type of diode it is. Rectifier diodes such as the 1N400X parts are also OK. I used a BAT85 small signal diode because I had plenty of these in stock.

11. A small 3 contact female connector, This can be cut down from a larger connector. These often come with wire and contacts, If not I have included some notes on this in the construction details.

12. A piezoelectric speaker or passive sounder. A plain speaker or sounder without electronics. This should have a high resistance and you may be able to see the piezoelectric element. Mine came from an old VCR.

13. A piezoelectric element, if you have to buy one they are readily available and low cost mine came from Ebay and cost 39 pence about 54 cents. These are usually a plain brass disc with the piezoelectric material bonded to it. The size I used was 35 mm Diameter as this worked well. But any size will work 27 mm is a popular size and is fine for this application, size is not critical whatever you have to hand.

14. You will also need a soldering iron, solder, long nose pliers and a set of side cutters. A multi meter is very useful but not essential, a labeling machine, hot glue gun and finally double sided sticky tape. I used the glossy plastic labels with my labeling machine as they are very durable and last well plus they look good and are easy to apply of to the surface of the container.. Plus they too stick onto the outside of the plastic container.

15. Some old pens, preferably ones that have run out of ink as we will be needing the plastic tubee inside and the plastic top for the plunger.

As both soldering and hot glue have burn and other health risks, ideally this item should be constructed carefully and precautions should be taken.

Eye protection should be worn.

Gloves to protect your hands from burns

A well ventilated place or better still a fume extractor should be used. The soldering iron solder fumes from the flux are an irritant.

Care should also be taken with drills , scalpels and any other sharp tools .

Regulations on this vary from country to country so you may need to see what the regulations are in your country.

My first effort on this is quite different to the final item. In my proof of concept I used an IR LED on a lead to drive the sounder or piezoelectric speaker. While this did work the volume was very low and this meant holding the device to my ear and moving the sensor to the remote and if that wasn't enough I still had to press a button on the remote. Not impossible but quite difficult.

I wanted a single piece solution that was much louder and that I didn't need to hold to my ear. Put simply: It needed to be louder! So many experiments later I found that the solar cell solved most of the problems and had some advantages. A smaller piezo speaker could be used and it's much louder. By using a separate Piezo element to generate the LED voltage the sound level is higher and we loose a switch. So all good, the solar cell issue challenged me to start with but I overcame that issue too.

I used a recycled mints container for this the size I used was 57 mm Diameter by 72 mm long. In our chosen container we need holes for :

Our solar cell window

Our LED holder (if used) or LED

Our switch

Our connector

A hole to let the sound out of the container

And the plunger to apply light force to the piezoelectric element.

From the description of this I have also included a some images of mine for guidance, but as everyone will have different parts I have not included exact measurements. None of the measurements are critical or the positions chosen for these items. As log as it is wired correctly and the solar cell is behind the window it should work fist time. You can wire every thing up first to make sure it works before securing the parts in the plastic container. As I have fitted my switch in the lid I recommend that this be mounted first along with the LED holder before it is wired up and the joints soldered. These sweets containers are made from soft plastic and drill and cut very easily.

The circuitry is simple and it should not take long to build.

The top of the container

The top of the container is nice and flat. I took advantage of this as this is larger than the bottom of the tub. However space was limited and I did want to use this particular container so the solar cell had to go on the inside of the cylinder wall, but I found a way to do this so I was able to complete the project. Its worth saying that hot glue and sticky pads and tape are really quite good way of using these soft plastic containers which are a little immune to most other types of glue and mechanical fasteners have a tendency to "pull through" the plastic.

The solar cell

I do have a nice solar cell which I had planned to use, it came as part of a rechargeable Key ring, which once the nickle cadmium battery dried out no longer worked, ideal I thought, this will work well. This was however not the case. There was no infra red sensitivity with this solar cell, so no output, I checked this with a volt meter and proved that this was indeed the case, not only that but there was no output from ultra violet light either. But plenty of voltage from visible light. I couldn't see any plastic film filters stuck to the surface of the solar cell either.

Weird but true, I didn't expect this. So I used a solar cell that came from a well known supplier, see part number in the supplies list. The big plus with an off the shelf solar cell is that you can download the data sheet and look at the graphs for spectral sensitivity or " External Quantum Efficiency" (voltage output ) and see what this is before you buy it, ideally it needs to have voltage output in the 600 to 1000 nm ("Nano Meter" light wavelength) range this is usually on the right hand side of the graph with the shorter wavelengths on the left hand side 400 nm). There may be a part number on the back of a recycled solar cell which you can google and see if there is any data too. It just needs to be small enough to fit inside your container and sensitive to infra red (IR) light. The one I used is quite small with good output in the IR range so I hope to be able to extend the functionality to include a 3 way switch and meter to make a simple light meter. But this will be for a later Instructables.

My final solar cell is stuck to the clear plastic window after it has been mounted with pieces of sticky tape or sticky pads to the inside wall of the plastic container.

The Connector

For this I used a "Molex style" 3 pin 0.1 inch (2.54 mm) pitch connector. You may be more fortunate than me and have a connector to hand or a pre-wired connector to cut this from that came as part of some scrapped piece of equipment. This was secured in place with hot glue. Common sources for these (and many other parts ) are old printers, old VCR's and old TVs. You can also add old computers to this list. There are many manufacturers of similar connectors. This is not critical and many different items will work just fine. I have included some images to provide guidance on this and a schematic. My connectors and pins came as part of a kit from Ebay in a small clear container with compartments.

Soldering wires to the LED

This requires some care , I have provided some images of this. The LED is constructed like one of those hard sweets with a soft center . What looks like one piece of plastic is in fact a hard outer shell and a soft clear grease like core material. The reason for this is that the light is bent by the plastic so that the maximum amount of light comes out of the LED. If the hard plastic was used alone the light would not be bent as much this would reduce the amount of light coming out of the LED. To overcome this a clear gel like plastic is used which bends the light more and we end up with a brighter LED. This light bending property is called the refractive index, If you fill a clear glass with water and place a pen in the water it appears to bend where it contacts the water. You may have seen this effect. This is due to the fact that water has a higher refractive index than air, It is an optical illusion but one that in this instance with LED's is very useful. "So what and whats this science lesson about"? You may say, well this is why we need to solder our leads to our LED carefully. We need to grip the leads of the LED close to the body with our needle nose pliers and then solder our pre tinned leads to its wires. This way the heat which is harmful to our LED is absorbed by the metal in the pliers( With the added bonus that we don't burn our fingers). That hard and quite thin "shell " on our LED is all that is holding it together. If it melts our LED will fall apart and be destroyed. We should avoid that outcome if possible. Once we have soldered our leads to our LED we can slide some insulation down the leads and solder the other ends to our circuit. I have included a schematic diagram so you can see both this and the practical layout. The switch should also be soldered carefully if it is a plastic body type.

The Plunger

This sounds quite dramatic like a major plumbing device but its simply an improvised lever to apply pressure to the piezoelectric element to generate the electrical energy to make our LED flash or glow . I used parts from an old pen for this. (the plastic ink tube).The piezoelectric element is attached to the bottom of the inside of the container with double sided foam tape. This allows the piezoelectric element to flex easily My piezoelectric element came with leads already attached.

I mounted my piezoelectric element on a double sided sticky foam pad and stuck it to the bottom of my mints container. So when the plunger is pressed it deforms the piezoelectric element and generates a voltage to light the LED. I also added the top of a retractable pen to the end of the ink tube with a little hot glue to the top of the cut down ink tube. just to keep it in place and make it easier to press.

Wire everything together

Its easier to follow the images than read a description so I have included some images and the schematic to help with this. its not complicated and shouldn't take much time. The schematic shows how everything is connected.

The Remote tester should be tested first

Once completed you can test the device before fully assembling it into the container. with a known good remote control with good batteries. Simpy point the remote with the window on the remote facing the solar cell and press a button a buzzing sound will be heard from the piezoelectric speaker. As can be seen from the schematic there are two independent circuits So both can work at the same time, but the main reason is it saves a switch .

Next test the LED tester.

First move the switch to the internal LED position (INT or INTERNAL ), the internal LED is connected directly to the piezoelectric element. Tap the piezoelectric element with your finger and the LED will flash/glow. Next move the switch to the other position EXT or External and insert a known good LED with its leads going into the outer two pins, tap the piezoelectric element with your finger and that LED should flash/glow the same way the internal one did. Its not critical which way round the LED is inserted into the outer sockets of our connector the LED will flash. glow just as well both ways.

The final test finds out which lead on our LED is Cathode or Anode, Reinsert the LED this time using the center socket (PIN 2) and the outer socket (PIN ), this time you will find that it only flashes/glows in one position. We have now found the Positive or Cathode of our LED in the position where it glows this is the center socket is positive.and that lead is the cathode.

Once this is done we can secure our parts to our container and snap on the lid then we are done. It only remains to apply the labels and we're all done.

This device tests the following:

LED Test:

This tests all LEDs.

Does it work and how well?

What color is this clear LED?

Which lead is which on this LED with two cut leads that are the same length.

IR Remote test:

This tests remote control handsets.

Does it work?

Do all the buttons work?

Are the batteries flat?

And any other use you can find for it.

I think I have asked all the interesting questions here, so lets take them one at a time

LED Test.

Does it work and how well?

To test the tester and so we know what to expect slide the switch to the Internal LED position. Next press the plunger (not too hard}, we should see our LED glow or flash If we then insert a recycled or new LED into the outer two holes in our socket and moving our switch to the external LED position and again pressing the plunger we will hopefully see our LED under test also glow. If not check the LED leads are making contact and try again. This works with all LEDs from IR LEDs to UV LEDs and all colors in between. The IR LEDs wont be visible to the naked eye, but their light can be seen by a smart phone camera. Open the camera app on your phone and point the camera at the LED under test and press the plunger. If you see the LED flashing on your phone screen then you know its an IR LED. The high brightness LEDs will be significantly brighter than standard LEDs.

LEDs are polarized and come with an Anode and Cathode. When new these are of different lengths and the long lead is the Positive (Cathode). But what if these leads have been cut and are now the same length? Well this is where the center connector pin comes into play. We can now insert this LED into the connector two ways, so we can identify the polarity of the LED.

The what color is this clear LED is self evident, we insert the led into the outer pins, press the plunger and as the LED glows or flashes we can see the color.

Finally on testing LEDs

Don't be too quick to throw any device that doesn't seem to work in the bin. It could be an Infra Red LED and not be visible to the naked eye or it could be a photo transistor that doesn't emit light anyway. A multi meter will be needed to check this possibility.

Remote Control Test {IR}

For this you will need to point the remote at the window on the tester and listen. It may not be very loud but you should here a buzzing sound when a button on the remote is pressed. I recommend that you do this for the first time with a known good remote with good batteries just to get the hang of it. You will find that there is a sweet spot for the remote for maximum volume. You can use this to guide future remote control tests. Once it is established that the remote works all the buttons can be tried to see if they all work. It can be the case that not all buttons work which can be a problem if its the on button! The most used buttons suffer the most wear and it can be the case that you can no longer turn that piece of equipment on with the remote. Try the on button on the device , if this works and the remote doesn't then its the remote that you will need to fix or replace,

I created this schematic using Tiny CAD (My fist time using this software) as it is easy to use and can be downloaded from their website and it is free.It replaces the hastily hand drawn schematic. I couln't find a symol for piezoelectric element in Tiny CAD so I used the capacitor symbol and added "piezo(electric) sounder" in the description. Hopefully I will find a way to create PDF files from a schematic easily too.

This took quite a lot of effort, but then it is my first published Instructables. I did have a lot of fun however and it did have its challenges and unexpected issues but all very worth while and I overcame each challenge as I went along. I hope this inspires others to not only write their own Instructables, but also to develop their own products.

I have managed to turn a set of items that would normally disappear into the bin into something really useful and turn trash into a piece of treasure that will be used many years into the future. I have also built a piece of test equipment that is entirely held together with double sided sticky tape and hot glue. No screws or other fasteners. It can however be easily opened and modified if desired. Good luck.