Constructing a front panel




Taking on the task of building a machine in a customised case is not without it’s challenges. As I soon discovered when I came to designing the front of the machine. With six LED’s, two switches and one illuminated power button. I had plenty to fill up the flat blank looking facia. But how was I going to go about it? I knew I wanted lettering under the various lights and switches to indicate function. But how exactly was I going to do it, without it look awful. Someone with money to burn, might have paid for chemical etching or some method that paints the letters on. On a budget I faced using a label maker and sticking labels on to the front facia. This was definitely not the look I was aiming for. The Altair had a wonder front to it and I wanted something similar.

It was then when I had an idea.

Placing the front panel under the flatbed scanner, I made a reasonably high resolution copy. I then loaded the image up and began designing where all the LED’s and switches would go. Having already sketched a rough design out on paper, with measurements of the panel and the components. I had a pretty good idea where things would be installed, which meant building it on the computer was fairly straight forward.

Printing a template out on my laser printer, I cut it out and taped it to the plastic panel. Then using a dremmel and a drill piece, I bore out holes for all the components. The LED’s where the trickiest part, make the holes to large and the LED’s would fallout, the fitting needed to be snug. With the holes made, I used a file to clean the panel up and removed the paper template. Offering the switches and light up, I found more filing/drilling was needing. So back to the dremmel I went.

It took a good hour of fiddling before all the components slipped in to their designated openings, but soon it beginning to look Altair-ish. I wont deny a sense of pride filled me, when I saw the front panel with all the components sitting in the case for the first time. Up until that point, the project had felt more a less like a pile of components. So seeing it come together for the first time was pretty satisfying.

With switches and light installed, I used a hot glue gun to secure the LED’s. With the wiring I know the chances of them falling out would be inevitable.

The next step was the actual facia or cover. Now this was the clever bit which I mentioned earlier. Having made a template on the computer, I had also incorporated in to the template all the various labels. Printing out another copy, I cut the out the holes for the LED’s and switches and offer it up to the front panel. Almost all the components pushed through the holes where they should. But several of the LED’s did not line up. As I had been cutting out the holes by hand with the dremmel, I guess I should be pleased at most of them aligned at all.

Taking measurements I went back to the computer and altered the layout, spacing the LED’s farther apart. This took me several attempts and many templates before I finally had one that worked. Finally with all the parts pushing through where they should. I was ready for the next stage. Making a final panel cut out, using thicker, high resolution card. When the printer spewed forth the finished version I saw a problem. Unlike normal paper the high resolution card had given the black ink a gloss look. With no way around this, I took a leaf out of my prop making skills and made a gamble. Using some Matt varnish spray I use for for water sealing decal paper. I sprayed the facia with three coats, with 4 minutes between coats. I then used a hair dryer to gentle dry the varnish. After 20 minutes it was dry to touch and had to my joy given the printed panel a Matt finish!

Using some 3M adhesive spray, I mounted the facia to the front of the case. Definitely heart in your throat work, as fowling up at this stage would have meant a big mess. As it where, it went on without a hitch.

One thing I was aware of when making the cover, was the need for it to be 3-4mm smaller then then actual plastic panel. As the panel it self, slid inside channels cut out along the front of the bottom and top sections of the case.
With the card attached the panel would have been to thick to fit. As the facia only needed to cover the visible surface of the front panel, it wasn’t much of a problem. Thou when the lid finally did go on, some trimming was need before everything went on properly. Even the best laid plans can run fowl!

Lets look inside Nomad the final chapter

With a melted PCB the front panel was as dead as an Aqua concert. So now I was faced with the prospect of having to rewire everything with a fresh LED PCB, providing I was able to get one.

Luckily as it was and I ended up buying two, as I knew what my luck was like.

Rewiring the front panel for a second time actually turned out to be very useful. As I was not only able to shorten the wires going from the regulator to the PCB, but also those from the PCB to the 4 LED’s on the front panel. Allowing me this time, the ability to mount the PCB on to the rear of the front panel. Once more using the handy retro 70’s solder/ray gun. I was able to get the whole job done in a surprisingly short space of time, not to mention ease.

Having done my research, I installed a 20 ohm resistor between the voltage out of the regulator and the PCB, preventing the circuit from drawing to much current. I had infact bought a 15 and 20, in anticipation of a 20 ohm resistor making the LED’s too dim. Luckily this wasn’t the case. After a quick test on the low voltage PSU proved the new circuit was working properly, I went about testing the larger Uniross. It was some time after all this, that I was to discover the Uniross was not actually powerful enough to boot the motherboard, not even as far as posting. But now I’m wondering off, so back to hooking things up.

With everything wired up on the kitchen side, I held my breath and press the power button, at first nothing, but then pressing a little harder the front panel came to life. five minutes passed and the blinkers where still working, I flicked through the patterns for a good 10 minutes, waiting for signs of over heating. Not a hint, the 20 ohm resistor had done it!! Hurrah

Powering the machine down, I went about placing the case back together. While the biggest hurdle was now over with, the next challenge, the one I had been dreading was finally upon me. Finishing the front panel. While the LED’s blinked, the Power LED worked, the Reset and Pattern change toggle switches worked. But the one thing which it needed was writing under each LED and switch, indicating what they where. How the heck was I going to do it? Decal’s? No, as I didn’t own a printer capable of printing white ink and yes they do make them. Etching? no as that would cost me a fortune and this was a budget, home brew project. It had to be something I could do myself. So after a lot of thinking, I stole and idea from my prop making skills.

In my next post I shall cover how I designed the front panel, it was a pretty simple job, time consuming, but a project that could be undertaken by anyone.

Lets look inside Nomad

Above is the circuit I built for the purpose of powering the LED PCB. At the heart of the circuit is a LM317 adjustable, three terminal regulator.

Initially setup without a 20 ohm resistor in line with the voltage out. This amendment to the circuit was needed to control the current feeding in to the PCB. Which caused the first setup to overheat and fail. In plain English, the microchip on the PCB melted, well near enough!

For the correct voltage to output from the circuit, the values of resistor’s R1 and R2 had to be determined. As my maths is terrible, I cheated by using an online calculator to figure out the necassery values. Which turn out to be 120 x 150 = 2.81 Volts. This was under the 3v given to the PCB by the 2 AA batteries that originally powered it. But given batteries are a constantly depleating power source, I did not think feeding a constant 3 volts in to the PCB would be healthy in the long term. Which is why I choose 2.8v.

I have to say that when it came to making this circuit, I found it quite a challange. I’ve always had a love for taking things apart, rebuilding them. But that has always been easy to me. It’s like working on a three dimensional jigsaw, where the pieces are components, which all slot together in a specific way. But making a circuit from nothing, this was something else, especially as I did not fully understand circuit diagrams and symbols. Luckily consulting several people online via IRC, proved the most useful thing I could have ever done. It is thanks to those individuals i was able to understand what i was doing and actually turn a rough diagram in to something that functioned.

With it completed, I connected a universal PSU outting 3v 1.5mah and tested the regulator. Nothing, the thing had zero output. except from when i hooked the voltmeter to the V in and ground. So something was wrong. I had nothing coming from the V out and Adjuster. While to this day I’m not sure how it happened. R2 somehow became perminently open, perhaps it was a faulty component, who knows. But for the cost of a few pence, i wasn’t really bothered. In addition to this, i had the feeling that my brief fight with a stubborn soldering iron, which refused to get properly warm. Had resulted in the regulator being damaged. In the end, I bought full set of replacement components. Using my dad’s older 70’s soldering gun, yes a gun with a trigger. I was able to fit the replacement parts in minutes. Honestly i dont know how i’ve managed so long without having this tool, compared the standard wand iron i have. The trigger iron, applies heat when you need it.

With the new components in place, i tested the circuit and discovered huzaar 2.8volts!!  When i saw the reading pop up on the multimeter I was relieved. As i was sure the reason for the fault had been something i had wired wrong. But no, the circuit layout as it turned out was good.

With the circuit tested, I set about putting all the parts together within the case. The end result was a rather full looking box of wires and parts and myself looking ever more worried something would surely come loose.

Switching from the universal PSU to the internal mini ITX power supply did not strike me as anything that would set off a red flag. Having taken in to account the 12v and 5v feeds, I had already worked out that i would steal power from a redundant HDD molex connector. When the machine powered up, it was on the kitchen side. Everything worked! Leaving the system on while I went for my camera up stairs. I thought five minutes turned on would tell if everything was working. I couldn’t have be more correct. On my return i noticed one of the LED’s was nolonger working. Flicking the switch, it came back in to life, while two others had died. Placing my hand over the microchip on the LED PCB to check the heat, the hot glue covering the chip stuck to my hands. It wasn’t warm, it was cooking! Powering down for 10 minutes and then back on, revealed the PCB was indeed cooked beyond repair.

It was at this point i realised something i had overlooked, the current! the universal PSU had a maximum output of 9v 1.5mah. But what rating was the Uniross adaptor i was now using to power the entire system through the ATX power connector? A lot more then 1.5mah.

Houston we have a problem

Yesterday I set about connecting all the jumpers and wires inside the computer, all was going well. Indeed I was feeling rather pleased with myself. This was short lived when I attempted to power the machine up and discovered the LED flasher board was not working. On closer inspection, I discovered two wires has come loose. Quickly out with the soldering gun, I had the wires reattached in no time at all. So back to powering the board. After a little tweaking of various connections and testing for conductivity before I powered up again, I felt satisfied that this time the board would work.

Flashing in to life, it was a sight to see all the LED’s on the front panel light up and working for the first time and being power from the internal ITX PSU as well.

My joviality again was not to last for long as i noticed one of the LED’s had stopped blinking then another, until all of them where out. Taking a look at the PCB, I went to place my finger of the microchip to test if it where getting to hot. Only to find a large glob of hot soft glue come off on my finger. The chip had not just got warm, it had fried itself.

At first I couldn’t fathom why this had happened. During all my bench tests, the pcb had run fine through the regulator I had build. The 2.8v feed should not have killed at all, that’s when it struck me. I had accounted for the constant voltage, swapping from the universal psu to the ITX psu. But I had not taking in to consideration the current, the level of amps from the test psu was 1.5mah, how much was it from an ITX power supply? I wasn’t sure, but if i had to hazard a guess. I would conclude in excess of 1.5mah’s. Add to this that the PCB for the blinkers is a very cheap and simple circuit that does not have a current regulator. So nothing was there to prevent the circuit from drawing more current then was needed. Effectively committing circuit suicide.

So today I am out again to out beloved poundland in the hope i can sauce another flasher unit, if not Thrashbarg has offered to design a circuit that will run from the 2.8 volt regulator i have made.

Fingers crossed i shall have it working this time, fourth times the charm I hope.