Plywood Monitor Project aka Upcycling an old laptop display to a new monitor

It is surprisingly easy to build your own monitor for a desktop computer by recycling the flat panel display from an old laptop.

I had an obsolete HP laptop with a nice 17-inch display which was about four years old. It had long since been replaced by something a lot more capable.

From that old laptop I built this monitor..

The monitor I built is on the left, my existing monitor is on the right.

This blog post is how I got from old laptop to new monitor. It was not terribly challenging and I figure most people have an old laptop somewhere and could tackle this kind of project in some shape or form with a minimal set of tools and electronics experience. I do not want to mislead any reader into thinking that I came up with this method for recycling old laptop displays. I know for a fact that I did not, and there are many tutorials on YouTube, Instructables, etc, which I urge anybody thinking of following in my footsteps to view. This is just a record of my attempt at this kind of project.

The first step was to power on the old laptop, and actually check that the display functions and was not faulty. In particular I was looking for those annoying dead or stuck pixels...

image source: http://electronicrepairing.blogspot.co.uk/

I personally can't live with those and I would not put the effort into this project if the donor laptops display had any of these faults.

The next task was to carefully take apart the laptop. There was no point in using brute force here as flat panel displays are quite fragile and very easily damaged, so carefully with screwdrivers I unscrewed anything I thought may be holding the display in position. I carefully set the screws aside in the order in which they were removed in case I wanted to put the laptop back together again or in case I wanted to reuse the display casing for the new monitor as well as the flat panel display itself.

Taking apart the old laptop and display

After taking apart the old laptop and gently disconnecting everything connected to the flat panel display, I had to find out the exact model and who made the display. This step is essential to purchasing the correct electronics I needed to convert the display from a laptop display to a monitor.

The make and model is usually displayed on the back of the panel on a sticker...

Red arrows point to the make and model

It might surprise readers that even though this was an old HP (Hewlett Packard) laptop, the display was in fact made by LG. Just because a laptop is sold by a particular manufacturer you cannot assume that the display was also made by that same manufacturer.

Armed with the make and model I searched Google for lp171wp4 tl n2 controller...

Which returned a load of results. I bought my controller electronics from eBay seller njytouch for US$37.49 including delivery from China. The electronics arrived as promised a couple of weeks later.

The electronics are quite simple to assemble. The connectors only plug in one way, and as long as you do not force anything, it is very difficult to screw that up.

image source: njytouch. Left to right. Lamp board, Main board, Control panel

These new electronics replaced all the electronics from the old laptop. It is simply a case of swapping out the laptops electronics for these electronics. No tools required! The main board supplied by njytouch has a number of options for connecting to your desktop computer.VGA, DVI-I and HDMI. Of these three options the lesser is VGA which is an old school analogue signal. DVI-I is a better quality pure digital video signal and HDMI is digital video and sound combined. I opted to use the HDMI connector.

The black cable with the golden connector you can see attached to the main board plugs into the back of the flat panel display. The only other connection to be made is the tiny 'lamp' cable coming from the back of the flat panel which plugs into that orange/peach coloured connector on the lamp board. Two connections are all that are required to complete the electronics part of this project. It was now a question of connecting my desktop computer to the mainboard with a HDMI cable and powering the new monitor with a DC power adaptor and I had a working if not very pretty monitor.

Njytouch recommends powering the controller with a 12 volt, 4 amp DC adapter, and sells an adaptor to do this from his eBay page. I actually had a 12 volt 1 amp adapter in my spares box from an old Netgear router. Although this adaptor could supply less current than recommended, it worked and saved me having to buy another adaptor.

Now that I had a working and functional monitor, I had to decide what I was going to house the electronics in. 

My choices were:

1. Do nothing and leave it all hanging out.
2. Reassemble the display half of the laptop and cut a few holes for wires, etc,.
3. Build a simple and functional case from plywood.
4. Go all out and hand carve a case from hardwood.

As there was no need to make a rush decision, I actually opted for choice #1 for two weeks. As this would be a second display on my gaming battlestation, this enabled me to position the new monitor in various locations and orientations. For a week or so I had the new monitor in the "portrait" orientation instead of the traditional "landscape" orientation. This was not as useful as I hoped with software applications optimised for viewing in landscape. Those two weeks were useful in determining that the best location was at the same height as my existing display and the best orientation was landscape. 

After toying with the idea of building an elaborate and beautiful hand carved case, I decided to build one from some nice Baltic Birch furniture plywood I had in my workshop. Before I get into that the simplest choice would have been choice #2, to re-assemble the display half of the laptop, and this is in fact what most people who do not have access to a woodworking workshop actually do. This is illustrated quite well in this lifehacker post, where the original display case has been reused and augmented with a Mecanno stand. I have also seen Lego used like this to build a stand.

image source: lifehacker / gawker. Reusing the laptop display casing.

I decided to build a case with the 18mm thick plywood with very simple and clean lines. the look I was going for was "if Ikea built monitors". The main tool I used was my home built CNC Router Robot which I have described in an earlier post. I could have made this just as well on my bandsaw and router table.

After making detailed measurements of the parts, I designed the casing in Siemens Solid Edge ST7 and imported the DXF drawings into CamBam...

Display Surround, Back Panel and Control Panel

Tilt adjustable legs

Base plate

From there I exported the toolpaths to G-code and cut them on my CNC Router...

Cutting...dust everywhere!

Finished Cutting

I cut all the parts like this then finished them by hand with a Japanese pull saw, then 80, 180 and 400 grit sandpapers. All that was left to do was assemble the parts with wood glue, let that dry and then give the entire assembly a rub down with Danish Oil.

Starting the assembly of the plywood case

The base and case assembled, and clamped while the glue dries

The tilting mechanism is some washers, 6mm threaded wash and some nylon lock nuts

The electronics were stuck to the back of the monitor with double sides foam tape then screwed to the back panel for extra robustness.

The completed monitor in-situ

Here you can see the monitor as it is today, including the control panel that I also made from plywood attached to the bottom of the display.

This was quite a satisfying project, and while I appreciate that not everybody has access to these kind of tools, the actual process of converting a laptop display to a monitor is within most peoples abilities. Your choice of casing doesn't need to be as elaborate as mine. I hope you enjoyed reading about it as much as I enjoyed explaining it.

Thanks for reading. :)

You can download my DXF files here.

Airsoft hit detector prototype

I had this idea for an electronic hit detector that would register a hit of an airsoft beeb and could be used in various props. This post is about the sensor circuit itself. In later posts I will detail the use of this sensor circuit.

Spoiler alert: If technical stuff bores you, skip straight to the video near the middle of this post.

I thought the most likely candidate for such a sensor would be to base it upon a piezoelectric transducer which is a little ceramic disc that outputs an AC voltage when squeezed.

Piezoelectric Transducers
image source: Wikimedia Commons

I'm pretty sure I am not the first to have this idea, and for the record I am not claiming to be the inventor of such a sensor. In fact I would be surprised by anybody alive claiming intellectual property rights as the circuit which I am about to describe that makes such a sensor possible was invented by Karol Pollak in 1896.

If I could build such a circuit and link it to a logic board which would contain some airsoft 'game' logic, it might make for an interesting prop. For example it may be used as a target which must be hit X number of times for the objective to be won or more than one of these linked sensors may need to be hit in a particular order. I'm sure you get the idea and can think of possibilities of your own.

As a logic board containing the game logic will run on DC voltage, the AC output from the piezoelectric transducer must first be converted to DC, and this is done with a variant of Karol Pollak's bridge rectifier circuit.

Diode bridge rectifier circuit
image source: Wikimedia Commons

I will explain in lay terms what is happening in this circuit from left to right. On the left the piezoelectric transducer (denoted by a tilde ~) is squeezed as it is struck by a beeb which outputs a a wavy AC signal. The AC output travels along the circuit until it hits the diamond shaped arrangement of four diodes, which act like one way valves. These four diodes convert the wavy alternating voltage to a one directional direct voltage which can be used by the logic board.

The usual way to experiment with these things is to first build the circuit on a reusable experimentation board known as a bread board, and this can be seen in the next photograph.

I added a green LED to the circuit and turned the lights off while tapping the piezoelectric disc (on the left). The LED just lit up for the briefest of moments, indicating that the circuit worked and could be used as a sensor. Luckily I found a superbright red LED which I fitted and made this short film, following an earlier fail (I will come to that), I protected the sensor from the direct beeb strikes with a temporary sheet of 3mm Lexan.

The previous film was a failure as I can confirm that piezoelectric sensors are not very robust (duh!) when taking point blank beeb hits. :D

 So with a working experimental version I built this tidier soldered prototype on prototyping board.

The black an red wire tails will be wired to a logic board which will be the brains of the sensor. I have in fact (at the time of writing this) already hooked up this sensor to a logic board and I am getting usable and reliable results. However these results are still in a raw state and I am still working out exactly how I intend it to function. When I have done that I will, do a more detailed post on the logic controller.

In the meantime here is a closeup of the simple prototyped circuit.

As I said at the start of this post, I really only wanted to cover the sensor circuit here. In future posts I will detail it's use as a prop in airsofting.

Thanks for reading and stay tuned, shortly I will have a working application for your interest!  :)

Update 13 Jan 2014, PM
I have been asked for a bill of goods for the circuit. Here is what I purchased from my preferred components supplier, RS Components. The downside is you need to buy significant quantities of the components as they sell in bulk. However this is still more cost effective than buying from Maplin who charge like a wounded rhino. For example the capacitors I bought from RS Components are over ten times more expensive when purchased from Maplin, the diodes over twenty times more expensive.

RS Stock No.	Qty	Unit Price	Goods Value	Description
159-5420	3	£3.84	£11.52	01-0171, Single Sided Matrix Board With 81 x 15 1.02mm Holes, 2.54 x 2.54mm Pitch
116-852	20	£0.042	£0.84	Panasonic 4.7μF ±20% 25V dc Through Hole Aluminium Electrolytic Capacitor
724-3162	10	£0.37	£3.70	Piezo electric transducer 15Vpp
739-0290	40	£0.023	£0.92	Small Signal Fast diode 100V 0.3A DO35

Some things to note:

1. If you are going to make one of these to experiment with you wouldn't need to buy the quantities that I did. I plan to build quite a few of these and will use these components in other projects.
2. You probably don't want the matrix board unless you want to build a soldered version. Instead you probably want the solderless experimental breadboard.
3. You probably want to use an LED to confirm that you get some output from the circuit.
4. Feel free to substitute the capacitor with one with slightly different values.
5. Shooting an unprotected piezoelectric transducer with a beeb will probably destroy it, as can be seen from my fail video.

If I get time I will also post a Fritzing circuit diagram.

...

Here is the Fritzing diagram

Adding radio comms to a German Army field telephone

I was asked a while ago if I could make an old bakelite German Army field telephone work as a walkie-talkie.

Bundeswehr field telephone, circa 1970.

It would be used by a WW2 airsoft re-enactor to communicate with the rest of his team in a more authentic manner. Even though it is no where near as old as a WW2 original it certainly is a very close relative, as can be seen from this photograph.

Wehrmacht field telephone, 1941.
Image copyright: The Museum of Technology 

It's a close enough match that you would need to be close up and knowledgeable of German Army field telephones to know that it is not WW2 era. This is fine for an airsoft prop for a casual re-enactor.

Both of us would have reservations on 'hacking up' an original WW2 object simply for the purposes of an airsoft prop. The 1970's field telephone comes from less important period in history and there are many more of them around, so we felt that it was much less of a travesty.

The approach I took was to externalise the mike, speaker and push to talk switch via the headset socket, which can be seen in this next photograph. The grey circular thing is the mike from the field telephone and the little black speaker is from the radio.

Prototyping the electronics

I later successfully also used the speaker from the field telephone but it was quite large, and I thought the current from the radio would not be sufficient to drive it at acceptable volumes, and this is why I initially used the radio speaker. In the end, it worked perfectly. I also initially used the mike from the radio, but I cooked it during the de-solder process and it was absolutely ruined. With a lack of spare mikes to hand I was (luckily) forced to use the grey one. Note also that in the photo above the black vinyl cable is not very WW2 looking. I stripped out the wire cores from the braided black nylon cable and re-cored it by hand with modern cable, so its olde-worlde on the outside but modern on the inside. ;) I also buggered up my hands with friction burns in the process. It looks like I have been abseiling without gloves :(

The field telephone headset integrated with the radio

In the above photo you will notice a grey bar on the headset. I wired this into the system and it now functions as a push to talk button. The system can be fully used, as pictured in the photo above. The base of the field telephone actually has no function in the rewired system other than looking authentic.

The complete system

With all the components of the system together it is ready for use. Hopefully I can get a pic of it in use to post.

As always, thanks for reading! :D

Airsoft Glock 18C NiMh to LiPo permanent hybrid conversion.

You might have read my first LiPo conversion project where I used the NiMh battery connector wired to a JST power connector to make my Cyma 030 (Glock 18C) run on LiPo batteries. If you haven't read it, I suggest you do as there is some background that I will not explain again here.

Link to my first LiPo conversion project

Again, I am not claiming to pioneer this process, just logging my experiences.

This second post describes my adventures in converting both a CYMA Glock and a Tokyo Marui Glock. Some of the pictures are of the CYMA and some are of the TM, but the process was the exact same for both.

I decided that I would prefer a more permanent connection by directly soldering the JST power connector directly into the wiring of the Glock. This would give a more reliable connection. I did not like the solder joints that I had made onto the stainless steel contacts of the NiMh battery connector in the previous project.

You are probably thinking that soldering the JST power connector would involve a significant strip down of the AEP. Not so, in fact all I had to do was remove and made a minor modification to one part.

For reference here is what I made in the first project. It is the NiMh battery connector soldered to a JST Power (female) connector. The solder is reinforced with blobs of epoxy resin.

The JST leads soldered to the NiMh battery connector.

I wanted to solder the JST leads directly to the wiring of the Glock. To do this I only need to remove one part which is an internal cover. This cover is attached by three screws, one of which is longer than the other two. I used a PZ0 screwdriver to remove the screws on my CYMA and a PZ000 screwdriver to remove the screws on my Tokyo Marui Glock.

The internal cover (CYMA)

With the cover removed I carefully peeled back the heat-shrink and soldered the red wire of the JST power connector to the solder joint where the NiMh battery connects to the AEP.

Soldered positive terminal (CYMA)

Then I flipped the AEP over and soldered the negative terminal. The photo below shows the soldered negative wire. You will notice that the wire runs outside of the battery eject lever with the Q.C. sticker. In order to close the slide I had to put the black wire on the inside of this lever. Otherwise it will be nipped by the slide. 

Soldered negative terminal (CYMA)

Ok, the last thing I had to do in this simple project is to make a minor modification to the internal cover I removed so that the new wires can pass into the battery compartment. To achieve this I simply cut off 4mm (1/8") on each side of the cover with strong scissors.

Snip, snip! (CYMA)

Then it is a matter of screwing this cover back on.

Internal cover on and battery fitted. (TM)

And from the other side.

Note that the black wire runs inside of the battery release. (TM)

I have described this as a permanent conversion, but it might be more realistic to describe this as a hybrid, because I could still use a NiMh battery in this AEP. So long as I was not stupid enough to fit a LiPo and a NiMh battery at the same time everything will work with either battery type. But of course, why would I want to use a NiMh again, when I have the punch of the LiPo?

The NiMh fitted and tested after conversion. (TM)

Another simple project complete with a great improvement in performance. Of course if you are going to sell your AEP on to a NiMh fan, you can always unsolder the JST power connector.

Finally, for those of you who would like to see the trades on the Tokyo Marui Glock...

Left side (TM)

Right side (TM)

Thanks for reading.

Comments

Q. Is the TM worth the extra money?
A. Well I don't really do reviews, but since I own both and can do a side by side comparison I would say yes it is for me. I have also heard anecdotally that the CYMA is more leaky due to the lesser build quality and that parts get loose, but have no evidence of that. The TM does have nice trades, if you are into that sort of thing but this is a fixed slide AEP. If you want realism you would surely be better off with a GBB pistol?
I would expect that the TM has a superior hop, with my previous experience of my other TM weapons. It feels slightly more robust in the hand, the slide and mag make nicer 'click' sounds when they are seated, a sign of build quality and finishing. On the other hand the CYMA is perfectly acceptable, if you are looking for a close quarters pistol that is reliable in colder weather and don't want to spend around twice the price for something which feels 25% better. This is all very subjective. That's why I don't do reviews...usually. ;)

Airsoft Glock 18C NiMh to LiPo Conversion

This post is about my adventures in converting an AEP to LiPo power.

But first, some background...

Airsofters know that cold is not good for gas weapons. The extreme cold makes the gas less gassy and more liquidy and so the beebs fly with much less power, if at all. Of course there are 'winter' gasses and CO2, but they still seem to be very temperature sensitive and CO2 in warmer conditions can make for a dangerously 'hot' weapon and put your pistol under a lot of internal stress.

The last thing you want is to have the airsoft equivalent of brewers droop when you really want to rely on your side-arm. You take aim at the bayonet charge, fire! and the beeb rolls embarrassingly out of the barrel and lands on your boot.

With this problem in mind, cold weather airsofters might want to consider the benefits of an Airsoft Electric Pistol (AEP). The AEP is battery powered, so there are no cold gas issues. Pedants will point out that cold effects batteries too. This is actually true, but generally the negative effect of cold on a AEP is much less than the negative effect of cold on a gas pistol. However if it is *really* cold, and I mean frigid cold, then you can expect problems with any moving mechanical device regardless of the power source.

The choice of AEPs is fairly limited however. Compared to the vast range of gas pistols there are approximately 5% to 10% of the choice of those models as AEPs. Worst still, of that small range of AEP's the batteries they use tend to be the older Nickel Metal Hydride (NiMh) chemistry cells. Now I should declare a bias. I love Lithium Polymer (LiPo) batteries and I do not like NiMh batteries. LiPos are small, powerful, light and contrary to folk myth easy to maintain, charge and manage. The golden rule with LiPos is to use a good balance charger, and don't abuse them.

I couldn't find an AEP that I wanted that was also LiPo powered. I do however like Glocks and I do like Tokyo Marui. So I ordered a TM Glock 18C AEP which is... stuck in f**king Customs. On calling the courier Parcel Force (more like Parcel Farce) I was told to expect a FOUR WEEK delay. The douchebags!  So as an interim measure I bought a clone of the TM Glock 18C, the ASG/Cyma Glock 18C. I am told that it is a very close clone, and can share batteries.

I decided to convert it from running on NiMh cells to run on LiPo cells. I did not invent this process. I have seen other posts on this, but I have found them to be lacking in specific detail.

Here is a picture of the ASG Glock with the original NiMh cell in black with the tiny LiPo I shall replace it with in blue with the protruding wires.

Glock meets modern battery technology

The LiPo cell is absolutely tiny. Here is a closer picture compared to a stick of gum and a UK Pound coin for scale.

So cute, you want to give them pet names!

For those of you who like numbers here are the stats:

NiMh

====

Fully charged: 7.29 volts, 500 mah

Discharge Capacity (C): 2 to 3C

Brand: Unbranded

Weight: 60 grammes 

Size: 91.1mm x 23.8mm x 12.0mm

Connector: Propriety

Cost: £9.95

LiPo

====

Fully charged: 8.49 volts, 300 mah

Discharge Capacity (C): 35C to 70C(peak)

Brand: Turnigy, Nano-Tech

Weight: 16 grammes 

Size: 44.3mm x 16.9mm x 12.8mm

Connector: JST Balance Charge Connector (White), JST Power Connector (Red)

Cost: £6.95

The comparison looks like this. Although the LiPo carries 60% of the duration of the NiMh. It delivers more voltage, for only 25% of the weight and 50% of the size and it can deliver about TEN TIMES the current. DO NOT LICK A LIPO ACROSS THE TERMINALS. ;)

That means the pistol will have a much sharper (immediate) trigger response as you will see in the movie at the bottom of this post, as opposed to the sluggish NiMh trigger response.

So onward with the conversion...

Not wanting to pull the innards out of the pistol  I opted as others have done to convert the battery and leave the gun entirely as it came from the factory. This prevents invalidating warranty or messing with the out of the box perfectness that is Tokyo Marui. There is also an added bonus, that it can go back to NiMh power if you sell the gun to a NiMh Luddite. ;)

The main strategy for the conversion is to remove the proprietary connector and solder it to a female JST power connector which the new LiPo will directly plug into.

First the disassembly of the NiMh.

This photo shows from the top a NiMh in original condition. Below it a battery pack with the outer shrink wrap cut off, and below that the actual shrink wrap.

Cut off the outer heat shrink cover.

Sorry this next image is of very poor quality and I flipped the battery by 180 degrees...

Carefully pry off the propriety connector

I detached the proprietary connector taking care not to break the metal contacts which I will later solder onto.

The proprietary connector detached and unbroken

I then soldered the JST power connector, observing the correct polarity.

Soldering to the steel pins on the connector is NOT easy

Just a bit of soldering and this very simple project is finished...

A LiPo now connected to a proprietary connector.

I felt that the solder might be exposed to movement and therefore cracking, so I reinforced the solder joints with some two part epoxy resin.

The solder joints reinforced with two part epoxy

I deliberately kept the wires long. I like having enough wire to easily remove and connect the battery. It all fits snuggly...

Fits perfectly.

I would not be tempted to buy larger LiPo cells. These are large enough and don't need to be forced which would risk damaging the battery. I bought two LiPos with the intention to swap them at lunchtime should the pistol receive heavy use.

Wanna see the performance difference of two fully charged new batteries?

Impressive, huh? LiPos rule!

Tools and materials used (as requested by Bap1811)

• Soldering Iron
• Solder (containing flux)
• Blade to cut the heat-shrink
• Long nose pliers to carefully tease off the proprietary connector 
• Turnigy Nano-Tech 300mah 7.4v 2S Lipo (from eBay)
• JST Power connector, female (from ebay)

Update 4th April 2013:

I have now created a second project with a permanent connection.

You can read this second post by clicking here.

Geeky LED Christmas Tree Ornament

I've been feeling a little 'Christmassy' lately and I decided to build myself a geeky Christmas decoration.

The idea is to build a wooden Christmas tree that has little blinking LEDs to represent a string of lights.

To this end I set about researching a suitable circuit which I redesigned to make it absolutely minimal in terms of complexity. The wonderful tool I used to do this is Fritzing. Think of Fritzing as a CAD package for circuits. It's free and it's great, I cannot recommend it enough.

So here is the Fritzing sketch of my circuit

Fritzing is just superb!

Designing it first in Fritzing helps you get your head around the design. So then I buit the circuit on a prototype board.

Sorry for the nasty mobile phone camera photo! :-/

My prototype board is a little small for this project, so I only wired three LEDs and not the ten that will be part of the actual circuit.

Next I cut the tree from 18mm MDF freehand on my bandsaw, painted it and glued it to a simple stand. You can see it here beside the prototype circuit for scale.

Feels like Christmas already!

With the prototype circuit copied onto a more permanent stripboard version of the circuit, I drilled some holes in the tree and threaded through the LEDs.

The LEDs 'twinkle' like little Christmas tree lights. Ho-ho-ho! Just in time for Santa Claus!