Thursday, November 26, 2009
The clock is finally completed and in an enclosure. I thought for a long time before deciding what the enclosure should be. I searched for aluminium ones from farnell and also RS, but could not find one of the form factor that I am looking for. I then decided to do one from scratch.
I remembered that I have some aluminium sheets in my cupboard. I found a suitable 3mm thick piece that can be used. There was a pair of them, but I could not recall what I initially wanted to use them for. I just need to saw off one end to have a suitable form factor for the tube clock. Time for some muscle power to do this... Sometimes I wished I had one of those rotary blade grinder to do the cutting... ok, I'm hardcore... I even wanted to learn welding so that I could fabricate my own enclosures.
Nice real wood of the size that I wanted would be difficult to find; or maybe I had no idea where to look for pine, ash and such wood in Singapore. For simplicity, I decided to go for MDF. I arrived at the dimensions while on the way to Syed Alwi Road for the MDF which would be used as the base. I always go to this shop as their cut is very precise. Down to the mm. The dimensions of the MDF would be 3/4" thickness and 67mm x 40mm (2 pieces) and 185mm x 40mm (2 pieces). I also wanted to go to Lam Chuan to get some nice wood grain veneer to cover the MDF base in order to achieve look that I wanted. But I am not sure if they would sell just a piece to me... and the office is real far off... in Sungei Kadut area.
While I was at Plaza Singapura shopping around, I walked into this scrape book supply shop. I've noticed this shop for some time, but did not pop in to check out their stuff. They always seem to be packed when I walk past. There were lots of very nice paper there. I liked it so much that I decided to use the paper instead of veneer. I thought it would look real cool. Lucas chose the colour of the paper for me. I actually wanted a darker green, but in the end, we settled for a lighter shade of green of "Embossed Polka Dot Cardstock" from Made with Love. I liked their sparkly paper too... and their other one... and... well, you get the idea...
I went to Robert's place to have the 3mm aluminium plate cut using a 20mm hole saw. There was this dot punch that I used there. Just needed to push it in and it will punch down. Very neat... I should get one of these. The drilling turned out much better than I expected. I think I surprised myself at the accuracy of my markings. Hahaha... after drilling the first hole, I thought the second hole would overlap into the first, but it did not. All 6 holes are very well done. Thanks Robert, for loaning the bench drill, digital vernier caliper and the hole saw.
The aluminium plate was sanded using my orbital sander. Hah... this I bought, cos sanding by hand is really very tiring. It was then sprayed using a metalizer spray that I found in my store. It did not give the super gloss effect that I wanted. I think I should buy one of those Mr Hobby Super Gloss and redo the surface. The MDF with the polka dot covering was sprayed using a flat matt lacquer from Mr Hobby.
Not everything went smoothly... Murphy's Law always seem to hit me... First, there was not enough clearance length-wise for the pcb to be fitted into the enclosure after all the sides are glued to form a frame. Luckily it was MDF and cutting slots along the edges are not too difficult. This can be done easily with a pen-knife with a large blade. Just be careful when doing so. This proves to be an advantage as the pcb can be "slotted" into the MDF frame without having any screws to hold it in place.
Second, an angle connector for the SMPS had to be used as there is just not enough clearance width-wise for a straight connector. I went to Sim Lim Tower to hunt for one. I could not find any new ones, but I eventually found some in a section where the connectors were taken from some other equipment.
Third, don't believe the markings on the wires of different SMPS devices. They are obviously not universal. I soldered the SMPS to the angled connector by observing the markings on the wire. I matched the same on each, but apparently, the polarity was reversed... Only suspected this after I turned it on and the tubes were not lit. I then checked with my meter and it was confirmed... Turned out that the on board fuse at the pcb was blown. It could have been worse. After replacing the fuse (well, i need to get the correct one later... 800mA fast blow), it worked.
Overall, this is a fun project. I'm tempted to get the GPS unit, but there would be no space for a GPS adaptor... unless I wire out that connector... Guess I will pass. I know of 3 more guys who are gonna get this kit from Jonas. Have fun guys!
More pics here.
Thursday, November 19, 2009
I've got the Nixie Tube clock from tubehobby since June I think. I just did not have time to build it and also did not have the mood to enjoy my DIY stuff.
Recently, I finally tried to build the kit. When testing the power for the B+, I did so without the PIC in place and without the tube as I needed to adjust it to 160V. However, when doing so, I could only get close to my input voltage from my 12v SMPS supply. I looked at the circuit and tried to trouble shoot according to the circuit diagram, focusing only at the high voltage section. No clue... I then emailed Jonas from tubehobby as a last resort. He replied promptly in the evening. He mentioned that the PIC would be required in order to generate the voltage.
With this tip, I retried with the PIC connected and viola! B+ is there! After adjusting for 160v, I worked on the tube board, mounting the tubes to the sockets and then connecting them onto the logic board. Plugging in a 12V 2A smps supply, I turned it on and the tubes are lighted. I noticed that on most tubes, there is ghosting of the seconds display over itself. Initially i thought it could be that the B+ was not high enough. Actually, I think the components were running in. After around 10 mins of operation, the digits were clear.
In that time, I configured the time and date and also the "sleep duration" of the tubes. I got this particular board from Jonas because it is has better features compared to what's available out there on ebay and the web. The neat features are the sleep mode and the battery backup. I'm so tempted to get the kit for the larger tubes. ;)
In the meantime, I'm gonna build an enclosure for this baby.
More pics here.