I recently moved our family’s personal storage from a ~14 year old QNAP TS-219P NAS to a new Synology DS224+ NAS, with roughly 2x the storage. The data migration went pretty smoothly, after a couple of false starts. I tried a “restore from USB drive” approach first. After all, both NAS types can back up to ext4 filesystems, so it should read OK, right? Unfortunately these copies take a looong time to complete, and the web UI provides no measure of progress to give confidence that it’s working.

I recently moved our family’s personal storage from a ~14 year old QNAP TS-219P NAS to a new Synology DS224+ NAS, with roughly 2x the storage. The data migration went pretty smoothly, after a couple of false starts. I tried a “restore from USB drive” approach first. After all, both NAS types can back up to ext4 filesystems, so it should read OK, right? Unfortunately these copies take a looong time to complete, and the web UI provides no measure of progress to give confidence that it’s working.

I recently moved our family’s personal storage from a ~14 year old QNAP TS-219P NAS to a new Synology DS224+ NAS, with roughly 2x the storage. The data migration went pretty smoothly, after a couple of false starts. I tried a “restore from USB drive” approach first. After all, both NAS types can back up to ext4 filesystems, so it should read OK, right? Unfortunately these copies take a looong time to complete, and the web UI provides no measure of progress to give confidence that it’s working.

Linux includes a bench calculator called bc, which can achieve remarkable arbitrary-precision results in very few lines of code. For ease of running, code can be embedded in a here document: fib.sh #!/usr/bin/env bash BC_LINE_LENGTH=0 bc -q <<end 0;1; for (i=1;i<1000;i++) {g=last;last+=f;f=g;last} end The BC_LINE_LENGTH environment variable is used to prevent long lines from being split with a \ continuation character. The -q flag suppresses the welcome prompt. The 0;1; bit just prints the first two results.

Swift 3 has a “decimal” number type that can represent values such as 0.3 that are inexactly represented in Double or Float types. According to this article: An instance can represent any number that can be expressed as mantissa x 10^exponent where mantissa is a decimal integer up to 38 digits long, and exponent is an integer from –128 through 127. Note this is not the same as Python’s arbitrary-precision integer arithmetic.

Linux includes a bench calculator called bc, which can achieve remarkable arbitrary-precision results in very few lines of code. For ease of running, code can be embedded in a here document: fib.sh #!/usr/bin/env bash BC_LINE_LENGTH=0 bc -q <<end 0;1; for (i=1;i<1000;i++) {g=last;last+=f;f=g;last} end The BC_LINE_LENGTH environment variable is used to prevent long lines from being split with a \ continuation character. The -q flag suppresses the welcome prompt. The 0;1; bit just prints the first two results.

Linux includes a bench calculator called bc, which can achieve remarkable arbitrary-precision results in very few lines of code. For ease of running, code can be embedded in a here document: fib.sh #!/usr/bin/env bash BC_LINE_LENGTH=0 bc -q <<end 0;1; for (i=1;i<1000;i++) {g=last;last+=f;f=g;last} end The BC_LINE_LENGTH environment variable is used to prevent long lines from being split with a \ continuation character. The -q flag suppresses the welcome prompt. The 0;1; bit just prints the first two results.

We have this wonderful sewing machine from the mid eighties, a New Home Memory Craft 6000 - instruction book is available here. The brand is also known as “Janome”. This machine can stitch letters and symbols using microprocessor control, sewing “emojis” before that word was widely known. When it was recently powered on after a few years sat idle, it was completely inert (apart from the work light). A local sewing-machine repair place took a look, said it was blowing fuses repeatedly, indicating a fault on one or other of the PCBs.

The following circuit is a very simple water leak detector, which I made 25+ years ago (!!) following my fiancée having a washing machine go wrong and leak all over her apartment. The circuit is not ideal - there are better designs out there. It was built with ‘what I had in my scrapbox at the time’. It’s purely analog, relying on the gain of the Darlington pair to provide reasonable on/off behaviour.

We have this wonderful sewing machine from the mid eighties, a New Home Memory Craft 6000 - instruction book is available here. The brand is also known as “Janome”. This machine can stitch letters and symbols using microprocessor control, sewing “emojis” before that word was widely known. When it was recently powered on after a few years sat idle, it was completely inert (apart from the work light). A local sewing-machine repair place took a look, said it was blowing fuses repeatedly, indicating a fault on one or other of the PCBs.

I still like my PMC GB1i speakers a lot. They are slim and sound great, but have one practical disadvantage in our house: our cat is heavy enough to knock them over. The relatively narrow spiked bases don’t offer much resistance against toppling. Sully, 6+ kilos .. no contest How are the steel spikes meant to “isolate” speaker cabinets from the floor, i.e. what’s the physics behind this hi-fi orthodoxy? Steel conducts sound quite well.

The voices (and tech) used in Amazon Alexa, are available for anyone to play with, free of charge - search for Amazon Polly. Update: Here’s the voice of “Brian” (British English) reading Lewis Carroll with the “Neural” engine setting eanbled. Jabberwocky Poem. Try Polly yourself here.

I seem to have collected a few old BBC Micros - approx 1983 vintage, so coming up to 40 years old. Before powering them up, I took the advice of Retroclinic and replaced the power supply X2 capacitors that are known to fail (damaging the power supply in the process). Retroclinic can also be found on eBay. Rather than use an old-style CRT, a Samsung LCD TV provides a much steadier picture, using an RGB to SCART lead such as this.

I seem to have collected a few old BBC Micros - approx 1983 vintage, so coming up to 40 years old. Before powering them up, I took the advice of Retroclinic and replaced the power supply X2 capacitors that are known to fail (damaging the power supply in the process). Retroclinic can also be found on eBay. Rather than use an old-style CRT, a Samsung LCD TV provides a much steadier picture, using an RGB to SCART lead such as this.

This time, it’s a Sony Vaio VPCEB4L1EWI, with i3-380M CPU. About two years old. Running Prime95 stress test, the cores were reaching 85 deg C and the fan was rather noisy. 1. Strip off the back plate, undoing all the visible screws, taking careful note of where they all go back - there are several different sizes and types. The back plate then snaps off - be careful with the small white lugs on the upper side here.

My work laptop (a Sony Vaio VPCF13M0E) had become very noisy, with the fan running full speed as soon as it did any actual work. A bit of googling found that this was a common problem. The original heatsink paste becomes dried up, and doesn’t conduct heat well. Here’s some pictures of the steps I took to fix it. Obviously ONLY ATTEMPT THIS if you know what you’re doing, and the machine is out of warranty.

More on the SATA / Acer T135 saga. Having got the PC to “see” the drive in the BIOS, it should be a simple matter of restoring the system volume onto this drive (or cloning it from the old drive), making it a primary, active partition (so it’s bootable into Windows), and off we go, yes? So I created 1 large partition for the system and restored onto it. Did this work?

Just came across a nasty little snag with SATA disk drives. I thought I’d write it up, in case you run into something similar. One of our family computers is an Acer Aspire T135, around 3 years old now. The 80GB hard drive is getting rather full and slow. Time for an upgrade. Step 1 - check what the existing PC can do. It has a spare SATA connection on the motherboard, so that seems like the best way to go.

Swift 3 has a “decimal” number type that can represent values such as 0.3 that are inexactly represented in Double or Float types. According to this article: An instance can represent any number that can be expressed as mantissa x 10^exponent where mantissa is a decimal integer up to 38 digits long, and exponent is an integer from –128 through 127. Note this is not the same as Python’s arbitrary-precision integer arithmetic.

Swift 3 has a “decimal” number type that can represent values such as 0.3 that are inexactly represented in Double or Float types. According to this article: An instance can represent any number that can be expressed as mantissa x 10^exponent where mantissa is a decimal integer up to 38 digits long, and exponent is an integer from –128 through 127. Note this is not the same as Python’s arbitrary-precision integer arithmetic.

If you go to the search bar in Windows 10, and type “settings” - there are now at least three different places you might end up: The one on the left is “System Information”. It’s been around a while. You’ll notice it reports “version” as 10.0.15063. Top right, you get to from the classic Windows control panel / System. It shows we are version 10, but gives no other information.

A friend lent me their Shure PSM300 P3T in-ear monitoring system today. This is a top-of-the-line piece of kit for weekend-warrior type bands, costing over £600 for just one monitor mix. http://www.shure.com/americas/products/personal-monitor-systems/psm-300-stereo-personal-monitor-system/p3t-half-rack-single-channel-wireless-transmitter Turns out that the actual RF signal being transmitted is straightforward analog FM. A £10 USB TV stick and the free SDR# software http://www.rtl-sdr.com/rtl-sdr-quick-start-guide/ can decode the signal and play it out of the sound card output in stereo.

Ages ago, I built a John Linsley-Hood design of phono preamp, first published in ETI magazine in 1992. This was considerably better than the phono stage in the integrated amp I was using at the time (a Creek CAS4040). For a couple of decades I ran this from my bench power supply, so it was definitely time for its own PSU. Rather than etching my own circuit board, nowadays kits are available via eBay that save a lot of that messy work.

Prototype receiver circuit based on AM26LV32 chip: The MagJack - a Bel Stewart SI-52008-F has datasheet here: http://www.farnell.com/datasheets/1731561.pdf The IC cleans up the edges of the incoming signals. With some level-shifting and AC coupling, the signals are OK to pass into an SPDIF receiver.

Here’s a graph showing the write performance to a Sandisk Class 10 memory card. The reason for the sharp dips in performance, are that the FAT filing system has to go off and allocate a new cluster every N writes. For example 512 byte sectors, 32Kbyte clusters, means a new cluster is needed every 64 writes. Another factor on the XMOS board is whether the code is running in ‘debug’ or ‘release’ mode.

Being able to read/write information from an SD card is probably the easiest way to get large amounts of non-volatile storage into an embedded project. I’m using XMOS StartKit, with the code from here The card reader is a part from Wurth Elektronik, Farnell / CPC part number CN18143 available here. The data and clock lines have 120 ohm series resistors, as this can help to absorb transmission-line reflections on the connecting wires (even though they are fairly short).

I recently got one of these great little digital scopes. It has a few serial bus decoding packages (on a try-before-buy basis). You get 36 hours to play with them. Unfortunately they don’t include I2S bus decoding. I2S is a bus standard commonly used for transferring digital audio around, for example between ADCs and DACs. No matter! You can capture and export full-resolution traces of signals via a USB memory stick.

An extremely simple yet capable compressor circuit is published by Elliott Sound Products,here (link updated 31 Dec 2023). Compressor Mk I I built the circuit exactly as-is (in an Altoids tin). Care was taken to optically couple the bulb to the photocell (LDR), using a perspex rod, wrapped in smooth tin-foil. The perspex came from eBay: http://stores.ebay.co.uk/thewholesaleposco2009 as did the miniature “Grain of Wheat” bulbs: http://stores.ebay.co.uk/GnA-MODELPARTS?_trksid=p2047675.l2563 This was put together, and sealed in heatshrink tubing, to make it fairly lightproof from external light sources.

I have an Ashdown Little Giant amp. Several reviewers have mentioned that this amp is not at loud as it should be (e.g. here). It all depends on whether the output levels coming from your bass are enough to drive the output stage fully. I have an active bass, but even with the input set on max, to get a decent output level I need the output volume control set to around 3 o’clock.