First play with the BitScope Micro

I picked up a BitScope Micro to teach myself a bit about oscilloscopes. So far I've only used the first analog channel to monitor the wave generator, but it seems to do what it says on the box:

The test leads aren't the best quality, but otherwise this looks like a useful tool. You can't expect it to be in the same league as the professional gear, but for the money it's great for learning.

Modifying the (Aldi) Lumina coffee grinder to produce a finer grind

I purchased one of the Lumina coffee grinders from Aldi a few years ago, but only just tried to use it for the first time recently. Even on the finest setting it was producing grinds that were very coarse. The product really should be marketed as a herb grinder in standard form.

As this machine uses burrs to do the grinding I thought I'd try shimming one of the burrs to bring the two closer together, hopefully resulting in a finer grind. This actually ended up working really well, and I've been using it at least three times a week for a few months now for all my coffee grinding duties!

Here's what you will need to do the modification:

• Useless Lumina coffee grinder.
• Suitably sized Phillips head driver (you'll want to make sure it is clean).
• Three 8x1mm washers (again, make sure they are clean).

First of all you'll want to remove the top burr assembly, which you can do by turning it clockwise:

You can see the tabs that lock it into place here:

Once you've removed it, flip it upside down and you should be able to see three Phillips head screws, you'll want to remove these:

Lift the metal burr away from the rest of the plastic assembly and you will then be able to fit the three 8x1mm washers as per the picture:

As you can see this has shimmed the burr by 1mm:

Fit the burr back onto the assembly and fasten the screws, don't go overboard with force though as they are just screwing into plastic.

Adjust the machine to the coarse setting and insert the top burr assembly, lock it into place by turning anti-clockwise.

Test out some grinding!

Fluke 17B+ multimeter review

This is just a quick and honest review of my Fluke 17B+ multimeter.

Pros:

• Excellent build quality and decent/safe input protection.
• Nice large screen with good backlight.
• Continuity tester seems fairly fast and the latching works well.
• Has a diode tester, frequency, thermistor input and can measure in the microamp range.

Cons:

• Hold function is not Fluke's auto hold (as you would get on the 87V), it simply freezes the current display.
• Only 4000 count with 0.5% +3 accuracy (DC volts).
• Not a true RMS meter.

The included TL75 test leads seem sufficient and seem to be of a reasonable quality.

As a hobbyist, this multimeter should serve me well. If you need more precision or you do AC measurements you might want to consider something like the Brymen BM257S.

I had assumed the 17B+ would have featured auto hold, so I was a bit disappointed about that (in fact it probably would have swayed me toward the BM257S) but I'm certainly not disappointed in the overall product.

A potential backup solution for small sites running VMware ESXi

Today, external consumer USB3 and/or eSATA drives can be a great low cost alternative to tape. For most small outfits, they fulfil the speed and capacity requirements for nightly backups. I use the same rotation scheme with these drives as I did tape with great success.

Unfortunately these drives can't easily be utilised by those running virtualised servers on top of ESXi. VMware offers SCSI pass-through as a supported option, however the tape drives and media are quite expensive by comparison.

VMware offered a glimpse of hope with their USB pass-through introduced in ESXi 4.1, but it proved to have extremely poor throughput (~7MB/sec) so can realistically only shift a couple of hundred GB at most per night.

I have trialled some USB over IP devices; the best of these can lift the throughput from ~7MB/sec to ~25MB/sec, but the drivers can be problematic and are often only available for Windows platforms.

This got me thinking about presenting a USB3 controller via ESXi's VMDirectPath I/O feature.

VMDirectPath I/O requires a CPU and motherboard capable of Intel Virtualization Technology for Directed I/O (VT-d) or AMD IP Virtualization Technology (IOMMU). It also requires that your target VM is at a hardware level of 7 or greater. A full list of requirements can be found at http://kb.vmware.com/kb/1010789.

I tested pass-through on a card with the NEC/Renesas uPD720200A chipset (Lindy part # 51122) running firmware 4015. The test VM runs Windows Server 2003R2 with the Renesas 2.1.28.1 driver. I had to configure the VM with pciPassthru0.msiEnabled = "FALSE" as per http://www.vmware.com/pdf/vsp_4_vmdirectpath_host.pdf or the device would show up with a yellow bang in Device Manager and would not function.

The final result - over 80MB/sec throughput (both read and write) from a Seagate 2.5" USB3 drive!

BlackBerry MDS proxy pain

I'm just having a rant about MDS SSL connections through a proxy. Non-SSL traffic will work fine, however SSL traffic appears to go direct even when proxy settings have been defined as per KB11028. My regular expression matches the addresses fine.

Surely people out there want/need to proxy all their BES MDS traffic?

DNS resolution on iPhone

I've been playing with a few iPhones lately and have had trouble getting WiFi working through our proxy. After much hair pulling the problem turns out to be a feature in the iPhone DNS resolver that refuses to look up any hostname ending in ".local". This also appears to be a problem on Mac OS X:

http://support.apple.com/kb/HT2385?viewlocale=en_US

With OS X you can add "local" to the Search Domains field and disable this behaviour, unfortunately it doesn't work for the iPhone.

Data destruction

After cleaning my home office I was left with some old hard drives to dispose of, this got me thinking about data destruction. In the past I cleared my drives with a couple of passes of random data using dd, but is this thorough enough?

This time round I have used a free bootable CD called CopyWipe (great utility, BootIt NG is also worth a mention). Each drive was given 5 passes, and then taken to with a hammer just to be sure. I've linked a picture to the "after" shot.

I can see data destruction being a larger problem as time goes on. I'd be interested to know the techniques others use for this problem.