Category Archives: Electronics

DIY solar panel from cheap solar cells – Does cheap solar cells works from eBay

Solar energy is the coolest energy source in the world. But because of its cost of energy harvesting systems, it’s not very popular among a lot of people. However, while I was looking for some cheap option for a DIY solar system, I found some sellers on eBay, selling solar cells for considerably lower prices. So after careful consideration, I ordered 100 pieces of solar cells, which cost me a 8.38$ with free shipping. It was branded as AIYIMA 100pcs Solar Panel Solar Cells. However, it’s specification says one cell provide 0.5V 320mA of current with an efficiency of 17.4%. And with that specification I could have maximum of 16W (0.5Vx320mA) from all of the cells combined together. Which isn’t much, but since 0.5$ per a watt is really a cheaper option for me. I’ll add a link below the post to eBay seller if anyone needs to take a look.

In a few weeks I received it with a well protected package including nothing but 105 solar cells. I had to check several of them to make sure they are working and all of them was given me an acceptable result.

Once I had satisfied with cells I had to decide what kind of panel I had to make. After a quick research I found for 12V system I had to make a Panel with peak voltage around 18V and for a 24V system, it’s going up to 36V. The reason behind that is, when a load is connected to the panel, voltage is going to drop as our setup. The more current draw from the load, the more voltage drop is occurring depends on various factors. At least if I am going to charge 12V or 24V battery for storing energy, I need a larger voltage than battery voltage for make it work.

In my situation, I went for 24V system for oblivious reasons. First one is preventing energy lost while transferring. Second one is I have planned to use inverter which work with 24V. The first reason is valid for everyone and in every system, unless if you use bigger wires or something. If you transfer the same amount of energy through wire in different voltage, According to P=IV, lower the voltage, current become higher and because of resistance of wire most of energy become a heated and lost way through the battery. So prevent that happening, we can use wires with lowest resistant, which is thick wires. Or use higher voltage to lower the current which is more likely less energy wasted as heat. In that way we can use thin wires which is more cost effective.

Here are 2 panel systems I planned. For 12V, Its use 36 cells in parallel to create around 18V. And for 24V system, it should be used 72 cells in parallel to get around 36V.

First, I had to solder each cell for connecting them each other. I used, excess pins from LED’s for my previous project for connecting each cell. However, in this process I had to scratch the back side of welding tape a bit of a make surface more appealing to soldering.

However to finish this process you might need tons of patience because of cells are very fragile, you most likely broke every one of them in this process. In my case I broke 20 of cells before the work done. So this might not be very cheap after all. But after a few practice rounds it can handleeasily without breaking.
After prepare 4 of 18 cell panels I used a plain glass to mount them using glue and connect them together for complete the panel.

In testing I was able to get 40V max in direct sunlight average to 38V. To be honest, I wasn’t expecting that much result from it. However, when I connect to load which is 12V DC cooling fan with 0.15A rating on it, the voltage drops 17.6V max to 3.6 V min depend on light intensity of the sun. But at the end, I could able to run that cooling fan with a maximum speed (I guess) without paying any electricity bills.

These cells are working and provide sufficient power for small scale projects. But preparing these cells is very hard. However, I’m planning to go for complete system with batteries, charger, controller and so on, and then I’ll be able to tell whether this cell are cost effective than commercial products or not. Then I can accurately calculate the maximum power they can provide and hopefully I will do that soon.

How Did I Fix Samsung Thin 64gb USATA MLC SSD Hard Drive – Revive From Dead

Months ago I was experimenting with USATA SSD hard drive and use it with my PC for a while. After a few days, I went for a driver update on my system and then System was suddenly frozen. So I had to restart the PC and after that HDD wasn’t recognized by the PC. So I did the almost every trick in the book to get it back to work again, but it was a really dead and nothing could detect that hard drive again. However, I thought it’s a driver update that kills the HDD, but later I found out my power supply is not good as I thought and I had to replace it later.

However a few days ago I had time to look at that SSD Drive again and as expected, it doesn’t show any response when connect to the PC, even BIOS couldn’t detect it. So I assumed it had hardware issues and went to find some resources over the internet. I expected to find datasheet and check it’s for possible faulty units. But unfortunately I couldn’t find datasheet, so I went to check the HDD board without any clue.

First, I checked USATA power unit for getting an idea and I got a low resistance reading for both polarities around 200 ohms and it was odd because of it should be having a one way resistance if it use any of rectifier diodes in the circuit. And I was guessing 200 ohms is acceptable because its drive in only 3.3V so it need lower internal resistance to get more power inside to get to work done. So, according to V=IR it’s draws 15mA in ideal but I had no idea it’s good or bad without any reference.

So I went further on the path for something looks bad and for my luck, I notice something looks like a capacitor, in the middle of path of +3.3V, given me readings of resistor but when the polarity change it’s given me a different reading than first one. So I immediately remove it from the circuit and check it and it’s again given me to the same result.

Since I didn’t have any reference I couldn’t find what that was exactly. So I draw the paths so I can see clearly what it could be.

As it’s clear it could be diode or resistor or inductor or fuse to go DC current through it. Anyway, there is no point of adding a resistor in this place so I could remove resistor from guess list. And also, no point of using inductor here unless frequency filter is needed. Since it’s getting already smoothed DC voltage it could be eliminated from the list. Then there is a possible chance to be it a diode but because of the same reason it doesn’t make any sense. Also adding diode here would add a voltage drop, possibly between 0.7V – 0.3V and it doesn’t seem right. However, it does look like capacitor, but it’s not possible to be a capacitor, so my only guess was it could be some sort of fuse. And it was acting as 1st line defense and my faulty power supply blow it. That all makes perfect sense. The only thing bothering me was, if it was a fuse and it is blow up by higher current it shouldn’t be giving me resistance reading between its terminals.

Anyway, I was out of options and I could not find anything similar to that in other hard drives I had. So I decided to go for fuse and take a risk for already dead SSD Drive. Then I short the paths like if it was a fuse. Then check the internal resistance between GND and +3.3 terminal and make sure nothing shorted in the paths. And then connect SSD Drive to the power and check for unusual heating. At this point I could have tested how much current it draws from the power supply and compare it with before, but I forgot to do that. So I connect SSD HDD to the PC and turn it on. Boom! It worked!

After that, I install windows 10 on the drive, test benchmark and everything was looking good. Unfortunately, I didn’t have any reference about how it was performed before, so I could have compared it. In my test, it was heat up around 400C without any cooling. I’m guessing it’s ok to be heating up without blows up anything.

In summary, this is not universal fixing method for fixing everyone’s SSD hard drives. My point is, you could possibly fix your SSD hard drives by following something similar steps. But you have to be extremely lucky.

DIY LED Computer Cooling Fan – For Light Up Computer Case

LED Case Cooling Fans are a good deal of nice looking clear PC cases in any type. And you can replace those fans with ordinary fans without any problem. So I went to upgrade my ordinary PC into cooler PC and then I find out good quality LED fans are quite expensive and lower price fans are not quality enough. So I decide to make my own LED fans and see how hard it can be.

First, I thought use handmade LED arrays for the lightning, but then I decide to use ready-made LED strips which is more suitable and very easy to work with. And you have to go with bigger cooling fan, because they have bigger space between the fans and housing than smaller once. Or you have to cut some fan blades to make enough space to put LED between them.

So here is the list I needed for the job.

1. LED strip (12V is better, make sure they can cut in the middle)
2. 120mm Regular cooling fan (Transparent ones are better)
3. Some white/ silver paint (If you couldn’t find a transparent fan)
4. Wires, Soldering iron, Glue or Double tape (you might want to check LED strip with that)
5. Paper cutter

Step 1
Dissemble cooling fan by removing the fan from its housing. Usually in the middle of back side you can find the lock for the axis. Removing it by safely you can remove the fan blade along with the magnet. Some of the fans are sealed and you may want to use some force to break, but if it’s sealed try to do the next step by skipping this.

Step 2
Measure the outer diameter of fan cover and cut the LED strip. Some strips contain transparent rubber cover for its looks and protection. You can remove it carefully to make LED strip more thin.

Step 3
Attach required wire to strip by soldering and attach LED strip into the fan housing as you planned. It’s better to use the thinnest wire you could find. Or use some coil instead.

Step 4
Check for any conflicts between fan blades and LED’s. If needed, use a paper cutter to peel off some material from the blades. when do that, make sure all the blades are getting the same amount of cuts or otherwise unbalanced load will be make vibration when the fan is rotating.

Step 5
Connect LED strip to power. If you use 12V LED strip and 12V cooling fan you can simply connect together with correct terminal. Or you may need to have different power sources to power them up.
After finishing this, I replaced my power supply fan with this and find out my power supply use 5V to power up the fan in initial state and only use 12V when the system generate more heat. So I had to connect separate 12V power to lighting LED strip. You can always get 12V from directly from PC power supply.

If you are not using a transparent fan, you should apply some paint over the blades. It will add a nice effect to the fan. And that’s it. Enjoy the new look of your PC.

Building 8 inch ported sub woofer box – Full size enclosure

Having a good sound system is fun, but what else is fun is making one by own. However, I already have a basic sound system and I needed to improve its quality.

When talking about quality, subwoofer is obviously the main factor because it’s pretty hard to get it right. As humans, we are less sensitive to lower frequencies so it had to be very powerful and to do that, we need precise technology to achieve maximum efficiency. For the any kind of subwoofer, enclosures is must for lots of reasons and it will help to reduce cancelation, distortion and improve ton of other stuff when get it right.


There are many types of enclosures, but Sealed, Ported and Bandpass enclosures are the most popular ones. Thus, each one has its own advantages and disadvantages. In short, Sealed enclosures are provided more accuracy output while Ported providing more loud output and Bandpass will focus on the specific frequency range and amplify it’s better than others.


So in my project I’m going to make a ported enclosure with 8” subwoofer for the several reasons. First one is my amplifier is based on TPA3116D2 which is capable of a maximum output 100W for subwoofer alone, but my power supply only capability to provide 65 watts max, So I’m not getting very good power output so I’m not going for sealed enclosure because it need more power to get the same loudness comparing to other types. Also, I already have a sealed enclosure box, so I’m not going to make it. And about Band pass, it would require some precise calculations or otherwise it would be sounds bad. Since I’m going to use cheap subwoofers I found on the market, I’m not going to get it right calculations and it’s a lot easier to build ported one without messing with those.


There is lot of designs you can use to make something like this. You can always find some good designs and helps, out there on the internet with tons of resources. With days of research I got this plan of enclosure from this site It is very detailed and looks accurate to me according to my research.

You can download PDF file from this link from their website.

First, I have to make cuts plan for MDF board. For the board I’m using 8×4 standard size ¾ inch MDF board. From one board I could have made 3 boxes, so I planned to make 3 of them for more fun.

I convert retard units to metrics, so I’m not getting any confuse. However since I do not have the correct tools for getting the job done, I asked help from professionals for cut the board.

After cutting is done, I used simple plain nails and glue for the keep it together build. At this point you can use screw drives instead nails, but you have to drill the holes half way through. In both cases there is a huge chance to board get cracking, so avoid that possibility much as I can, I used thinnest nails I could find.

Halfway through the building, I started painting work. Because it’s very important to seal MDF board completely, or otherwise toxic that leaking from MDF board might get you a cancer or something. However the painting MDF board could be a hardest part of the whole process. For any kind of finish you have to use some kind of primer base. In my case I used a generic wood sealer to the first coat. Then sand it and apply paint on it. For glossy finish or better looking finish you may have to go for more layer of coatings and sanding. But in my case I don’t need to get nice look, so I end up with just a painting box with minimum effort. you can clearly see how bad is my paint job. 

After painting I attached speaker terminal, connect wires and tape loose wires in to the box or they will make rattling sounds when box works.

When finished the wiring I attached the speaker and seal the box. When you attach speakers to box use sealing material between speaker and enclosure to ensure an airtight seal between it.

After finishing, check for air leaks in box and seal them properly with glue or any other material. You can easily spot the leaks when playing some high base from amp, you can feel the air coming through.


For the whole process it cost me at around 9000 LKR to complete 3 subwoofer box with drivers. My expenses as follows.

For MDF board LKR 3750.00

Cutting LKR 800.00

Paints LKR 1000.00

3 Subwoofer Drivers LKR 3000.00

Nails and other costs LKR 500.00


Total cost is LKR 9050.00 which is around 56$. For one Subwoofer it cost less than 20$ and that’s so much cheap considering other options in the market.

With this subwoofers I will attempt to make complete surround sound system in a later post.

Something To Do With Broken Screen – Turn LCD Panel in to Illuminated Backlit Picture Frames

When you have some LCD panel from old laptop or monitor or TV, there are lot of interesting projects you can try to do. However lot of projects are limited on usability of panel and it’s condition. Anyway last week I got 2 broken LCD panels from laptop and I was too excited to do something interesting with it. Since both panels are broken I’m going to make good old Illuminated Picture Frame or Backlit Picture Frame withing those. So if you got working LCD panel you can try some other projects like, Smart Mirror or Secret Monitor and projects like those. 

So my plan was remove LCD or TFT panel from it’s back panel and power up that backlit panel alone and make picture frame withing it.

My LCD panels are comes from Dell inspiron series laptops, so it’s contains LED back lit panel which is suitable for my project. Unless your panel is too old or too good, model number isn’t going to be problem. If your panel too old it will contain florescent bulbs to illuminate back lit panel instead LED’s on newer panels. It won’t be problem but those will consume more energy than LED panels and unlike LED’s you will need special driving circuit to use it. If your panel is too good, if it’s something like OLED or AMOLED panels, you won’t be able to find separable backlit panal and you have to go for another project to try. 

If you got separate your panel from it’s housing or from whatever it’s source like these you are good to go.

First step is separate back lit panel from whole unit. It’s depend on type of panel and usually panel is stick together by tapes or ticks. In this panel, it’s easily separated after all tapes removed.

After separate you can see there is some connectors coming from back lit panel witch is used to power up panel. Usually those connectors connected to LCD control board by somehow. You should be carefully separate those from each other. 

Next thing is find paths and power up back lit panel. In my case there is 5 lines comes from panel and I assumed widest line for V 0 ( Ground ) and others are different set of led +V Lines. Anyway in this step I have connected this to the power supply and tried to power up panel by starting with 3V but couldn’t get anything up to 19V. So I deiced to break through panel and see what it’s made of.  

After break through I found one LED strip with 3 set of 9 LED series, which is total 27 Led’s on the line. And also I found out I need  27V (3V * 9LED) for the power up this strip in rough estimation and unfortunately it’s turns out I don’t have the right equipments to make enough voltage to run this panel.  


So for now I’m stuck with this step but I’m going to find solution for that pretty soon. So if you have same problem and couldn’t power up panel, remember that dissemble back lit panel will almost screwed the panel. It will be not same as before it was.

Something to do with classic phone

Use classic phone reciver with your mobile phone

Everyone loves some classic stuff in our houses not in use at all. we never things to throw them away because that feels sad. and it’s not bad because there are plenty of things to play with them. lets begin with old phone that we are not use anymore. here I had that old CDMA phone. not much old but it’s kind of old stuff. I like it’s receiver more than modern mobile phone because it’s feels good. today I’m gonna use this with my mobile to make calls.


For this project we need 

  1. Solder
  2. Soldering Wire
  3. Old headset or 3.5mm audio jack with 4 channel
  4. wires
  5. multimeter

We are going to just easy stuff. first we identified paths of receiver. in this case receiver has 4 pins and it’s basically divided for 2 pins for mice and another 2 for speaker. Just remove cover in receiver and use multimeter to identify paths. 

If someone not interest in keep this and whole other phone in this case just skip next step and cut this wire and move to next step. for me I like keep whole thing so I dissemble old phone and identified connector paths in there. 

After identified correct paths it’s time to connect those in to 3.5 mm jack. just remember if you are use regular 3.5mm jack, you have to know it’s pats which support to your mobile phone. different mobile phones use different wiring. so it’s depend on what kind of mobile you use for this project. here is some diagrams that use common mobile manufactures. however if you have working headset you can check your self what are the paths are like that.

After done that you are ready to directly connect those in to receiver. just solder those in to correct places. Use left or light one channel and ground for speaker. and use mic and ground channel for microphone in receiver. and it’s done.

if you are smart enough you can use switch from old phone to answer and reject calls. let’s do that later.

However there are few drawbacks in this way. speaker is not loud enough and other person hear what he said again. and sounds quality was terrible. So after all this become useless ^^

Anyway I have find some solutions and I could reduce those problems.

  1. I disconnected all the paths that connected in old phone main board via receiver jack. 
  2. I used another speaker and mic taken from broken headphone and headset.

Those reduced my problems to almost zero. so I have classic phone receiver to answer any call with pleasure. 😀