An Update On AN8008 Multimeter

I wrote about the AN8008 multimeter.  I have been generally happy with the meter.  But more recently, I started to notice some problems: the meter sometimes does not start up correctly, I have to turn the rotary switch a few times; and more annoyingly is that the resistance measurements seem off: the shorted resistance can be 5 to 10 Ohms or more.  Initially, the meter also displays low-battery sign;  I measured the batteries; it seems that they should be OK.  But I changed batteries anyway, but the things did not improve.   I suspected that the rotary switch contacts might be the issue.  I opened it up and found solder flux residue on the PCB circular tracks that make contact with spring clip on the rotary switch.  I cleaned the board with alcohol; the flux was easy to clean.   After that the problem seems to go away; the probe short resistance is about 0.2 Ohm.  

It is interesting the flux residue that has migrated overtime since it was not a problem initially.

More on Atomic Pi

I wrote about Atomic Pi about two years ago.  Recently, I started using it again as a desktop computer.  I like it for the quietness without a fan.  As a desktop computer, which it is not really intended for, it is under-powered.  The most severe limitation is the 2GB RAM (maximum possible for this Intel Atom processor), which is not enough to support web browsers' full functionality.   The SD card and the buit-in eMMC memory are relatively slow as a swapping device, especially writing (eMMC average  120MB/s read, 32MB/s write and 0.38ms seek).    A solid station disk on the USB 3 is a better alternative; the benchmark shows 417MB/s read, 396MB/s write and 0.24ms seek.  Initially I used a USB3 hub, but the disk is not working properly with the hub.  So the USB3 solid state disk is plugged into directly the lone USB3 port.  We still need a way to connect other USB devices, such as a keyboard and a mouse (although a Bluetooth keyboard/mouse is another option if no other USB devices are needed.). There is a USB2 port, but it is a 2mm JST connection.  So I had to make an adapter to connect with a USB hub.  The 5-pin connector pinout is GND, 5V, D-, D+, GND; I wired it a USB A female connector on a small proto board with a ribbon cable, with the shield grounded.  At least 2GB swap space is recommended.   Now it is usable as a desktop device.   I installed Lubuntu, the lightweight version of Ubuntu; it works adequately with multiple applications running.  I do not think Windows can run adequately.

Another device to explore is the XMOS processor that is used as an audio processor.  It appears programmable.  We'll see if we can do something with it next time.