Zagadka's Site

Kids are lucky these days.  Hardware is cheap and heavily abstracted in software. USB to TTL serial about $2 AUD. A knock-off Arduino Nano for $4 AUD both with shipping included. Took about 5 mins to get a push button flashing LEDs and sending a message on serial. You can count the lines of code on two hands. Beats the hell out of writing 300 lines of assembler. (but it isn't as fun)

Tonight I fired up the high voltage power supply and had a go at getting this EM84 display tube going.

+250VDC on the anode, The grid is being operated between -20VDC and 0VDC. The heater on this tube is 6.3V.

Positive terminal on an isolated bench supply is connected to the ground of the +250V supply to give negative voltage required to drive the grid. The negative is fed into pin 1 via a 1meg resistor to ground.

As the grid voltage aproaches 0V, the shadow widens. I put up this video demonstrating adjustment of the grid.

Had a small win with some Logitec speakers today. They were exhibiting poor volume and distortion. My first guess was caps, they looked sound, but were cheap crappy caps. I re-capped it anyway, with no result. There was also a suspect SOT-23 transistor which drives the power LED, when touched, the distortion changed. I deleted the LED circuit and connected the LED with a resistor direct to the power rail. No love. Then I noticed that touching part of the board near the power switch caused the volume to increase and the distortion improve. I shorted across the power switch and the unit came to life. I didn't even suspect the power switch, it is a sealed self-contained unit which is built into the back of the volume control. So I shorted the switch with a blob of solder (no chance getting a replacement dual gang + switch unit). Now the unit works great. Just with no off =)

Fixed up a bunch of little annoying non-technical things around the house today. Tap handles, leaking toilet cistern, broken light socket and other random stuff.

I headed out to the Postgres high availabililty meetup. The meetup was really good. They went though in a lot of detail the native replication now built in (as of like 9.1 or something) to Postgres. I will be switching my postgres replication from Slonyl to native for sure.

Somebody managed to snap off the FC to SAS adapter in the back of a set of disk drawers on the SAN. So I cam up with this special tool. =P

I scored this cool little compressor - something I've been missing in the shed for a while now.

Should make a bunch of jobs much easier.

Here is what the power does when you turn on two chassis worth of MicoCloud servers. Click the photo to see other power graphs (turning off an IBM chassis full of HS21s.)

Looks like a trip down to the DC soon to rack up these new drawers. Netapp DS2248. 24x 900G x 4. 86.4TB raw. Drooooool... 

Looool $34.98. Tell 'im he's dreamin...

The kids begged Mummy last week to drag this car off the council strip from up the road. The battery is stuffed and it only goes in reverse (switch stuffed). I've replaced the reversing switch with a relay - all it needs now is a battery and it's good to go.

Random Elasticsearch fact: When running Elasticsearch from within openvz containers - make sure that you give them veth devices rather than just IP addresses. Otherwise zen discovery will not work.

Proxmox is working out great as a home server. I have many small containers performing various tasks - all with puppet managed config.

This makes it much easier to manage and buildup/teardown when experimenting with different things. Much easier than the previous setup which was one monolithic server which had all the services on it.

When working in IT, you often accumulate a lot of hard drives. Here is a box of drives which are going to my mate for scrap. He collects the aluminium and magnets from them.

4 Digit Nixie Display prototype is running with the basics without the BCD-10 (4028) and Shift Register (4094) fitted for multiplexing. Running all anodes on for testing.

Unfortunately the previous NPN transistors which I grabbed to drive the bases of the PNP transistors which control the tube anodes were too small. The leakage from emitter to base on the pnp transistors was more than they could handle. Consequently the 4000 series CMOS chips got nuked too =/ I had no throughhole replacements, so I settled on some SMD transistors which I had stashed rated at 400V. No chance of them breaking down. I will also be addding some opto-isolators too...

I was given an old tube based high voltage power supply. It looks a bit dodgey - so I'm going to scrap it for parts. There were two nice 150V argon voltage regulation tubes in it though (OD3). There is a potted high voltage transformer module which gives a nice range of taps 425V at 100mA and also a 5V 2A tap for heaters. I will probably end up using this potted module as the basis for a bench supply (A much less scary, much more insulated one).

Today I built a chisel sharpening jig loosly based on John Heisz' design, without the trimmings. It turned out pretty well. Fixed 30 degree bevel, not adjustable. Two of the chisels were pretty far gone, so I ran them on the belt sander first to get the bulk of the material removed. This also fixed the leading edge and made it square again.

I've been implementing logstash at work. Interesting stuff. The elasticsearch cluster is up and running and working great. There isn't really anything to give it a really solid workout with just yet. I have been feeding it about 3000 lines a day worth of power data which I am graphing with Kibana, but that's about it. For starters I've got 180-odd machine cluster which I am going to be reading logs from with the logstash agent and sending them over to elasticsearch. There will be a redis cluster sitting between elasticsearch and the logstash agents. I decided to implement two haproxy/keepalived setups with floating IPs for the Elasticsearch and for the redis cluster. I went with this because although Elasticsearch takes care of this by it's self normally, some code does not handle being given more than one IP or hostname to contact Elasticsearch with, the same goes for the redis. So floating IPs will solve this, it will also mean that I can add more nodes and not touch the config on either the logstash agent or on the logstash redis/elasticsearch boxes. I can't wait to try it out, the individual bits are all happy and some of the parts which can communicate are tested. Currently I'm waiting on changes and approvals and stuff to go through so I can open up the required ports and install the logstash agents.

A roof space adventure! I had to get into the ceiling to investigate a noise we were hearing, which sounded like it was coming from in the ceiling. Of course this noise is intermittant and did not occur after all the effort of getting into the roof. I had to cut a piece of pine to fit across the bath tub to hold the ladder up under the manhole. It's in a really stupid spot (see photos). During the investigation I also discovered another reason why the airconditioning performs so poorly in this house. It appears that rather than getting a new AC plant when the house was extended, the owners simply bodged on another duct. I mean bodged, The main outlet to the airco is a trapezium shape with two ducts coming out like normal. They have just cut a hole in the top face and bodged another outlet on - the cutout is still sitting on top of the unit. I may modify this later, it's crap, you have to run every outlet all the time, there is no day/night modes to switch between bedrooms and living areas. I also discovered that there is a massive water heater in the ceiling too.

Finishing up the last day of Puppet training today in the city. It's been good to get a better understanding of how to start out from scratch and fill in a lot of gaps in fundamental knowledge which I missed being self taught. At work I help maintain existing modules, but rarely write new modules - so this is great. Another cool tool for the toolbox.

Racked up an interesting bit of kit today. Very nice in deed. Supermicro Microcloud 5037MR-H8TRF. This beastie fits eight E5-2600 v2 based systems into just 3U height. The units that we have currently are fitted with 32GB of RAM, but can take up to 128GB. The additional dual gigabit ethernet modules were removed and dual 10G SFP+ adapters were fitted. Each blade also has IPMI and the ability to directly plug in KVM (via dongle). They look awesome. The front of the chassis contains 16 3.5" drives. Two disks per blade. Click the thumbnail for more images.