Want to drive a E17 3W UV-C bulb (the germicidal one, generating ozone or not depending of the version of the glass) from USB (or any battery)?

Use this DDTCCRUB 4S-2A Battery Charger Module Step Up Boost Li-Polymer

Change the RCS resistor from 50mOhm to 125mOhm (0.125 Ohm) to change the charging current to 300mA.

Remember, these bulb have to be supplied 16V (min) so the filament starts glowing, but once the arc is established, current has to be limited to 300mA (settling at around 10V)

Don’t let it run more than few sec on the front of your naked eye/skin.

We all experienced it: light flicker! When concentrating on a piece of work or dead tree text, the light suddenly goes berserk and flash like a stroboscope on the dance-floor.

After fixing a TV with LED backlight, let’s dive in different performance of light fixture/light bulbs.

This effect is especially present in LED light fixtures where there is no inertia: incandescent or fluorescent light have a thermal or phosphor inertia and continue to glow a flick of second after the power is cut. But not the LED (even though there is some phosphor in them), this leads to have a close relation of the light intensity and the supply voltage.

Most of LED light bulb are supplied from main, the quality of the AC/DC converter takes a main role here. Because good rectification and filtering cost, manufacturer are cutting them, and you get this effect.

You can find two type of power supply on LED bulbs: simple rectification with LED string to match the AC rectified voltage. Or AC/DC converter with inductor and constant current control (this is what you want).

I wanted to “quantify” it, more that just a feeling, but didn’t want to drop hard cash (k€$ range) for dedicated equipment.

So I used one of the simplest and cheaper photo sensor on the market: a NPN phototransistor, (not a photoresistance as the bandwith is to small), in addition with a 10k resistor, connected to the GND (ring 2) and MIC (sleeve).

Then use a simple Android software, called Oscilloscope

The result is then very straightforward, especially in spectrum analyzer:

I now always have this small 3.5mm 4 ring photo-transistor adapter in my pocket when shopping light bulb/appliances in home improvement, so I can point it and discard the worst devices.

If someone comes up with a better idea, to measure more accurately amplitude and ideal the spectrum (would need a dedicated color sensor though), with an easy to use interface, that would be awesome.

Just found the perfect bag for the awesome tiny portable Bluetooth speaker.

The Reisenthel allrounder S

• Size (W x H x D): 32 x 24,5 x 16 cm
• Volume: 8 l
• Modeled after the traditional doctor’s bag: the contemporary interpretation of mobility!
• Lightly padded lateral walls and bottom
• Opening includes zip fastening and integrated metal bracket
• 6 inside pockets for practical storage
• 2 long carrying straps
• Material: premium-quality polyester, water-repellent
• Item no.: MR7003 EAN: 4012013546136

We love to listen to FIP, as it’s a public radio, without commercials and not so much speaking.
Unfortunately, this radio is FM brodcasted in only few city in France, and here in Grenoble, the only way to get is internet.

So we built this small kitchen radio, music playing in 14 seconds, and quite pleasantly aesthetic, in the same line as my previous nixie clock.

The large solid aluminium knob with amplifier pot ON/OFF produces a comforting click to power ON/OFF the device or adjust the volume.
The shiny stainless steel button is for future upgrade to allow changing from few radio as currently only one is available.

Hardware part

Here are almost all the items needed for this DIY hack:

• Ikea box (4€)
• 4″ coax speaker (scrap)
• 1″ tweeter (3€ on AE)
• Rpi 3b (40€ on Farnell)
• USB sound card (5€ on AE)
• Stereo 5V amplifier (1€ on AE)
• aluminium knob (5€ on AE)
• stainless steel push button (1€ on AE)
• C5 pannel connector for main supply (0.1€ on AE)
• USB wall wart (scrap)
• piece of 5mm plywood (scrap)
• speaker fabric for front pannel (4€ on AE)
• 30cm of leather belt (scrap)
• washed nuts (1€ on AE)

A total of about 60€

Step by step assembly

Let’s remove the USB sound card along with the extra not needed capacitors and jack connector (desoldering station is realy a must here)

Make a slot for the micro SD card on the back: remember, the Wifi credential are stored here.

A XY table on a drill press was usefull, I didnt imagine bamboo being so hard to mill.

Piece of leather bought in Texas, this is what’s left from my buckle-less belt I made few years ago, it could be an entry someday.

With the washer nuts, it look nice.

The C8 pannel connector, wired to the wall wart.

Everything fitted in the box, held in place with double side tape (the brand Multicomp from Farnell is nice).

Adhesive rubber feet add an extra touch.

Piece of plywood for the front panel, black mate painted, with the speaker cloth.

Held in place with thin double side tape.

Finish

Let’s add a small tag to give some identity to this yet unbranded product. A nice friendly name, with our initials to personalize it even more.

Warm up kicad and start just a PCB without schematics, with a beveled edge to add a touch of design:

The result is very good, with this mirror finish!

Once glued on the product, it does raise the bar. (a pitty the manufacturing reference is on the front, next time I’ll do my artwork on the back, just to make sure it’s not on the front)

A quick video:

Software part

Download RPI image

Download a RPI image, in this case, I choose : pipaOS A lighweight, fast, Raspbian based distro for the Raspberry PI

Once the image unziped, copy to a fresh high performance micro SD card

sudo dd bs=4M if=./pipaos-tamarillo-4.7.img of=/dev/mmcblk0

in order to boost performances, I use a Samsung EVO+ for high performance for a very fast boot

ssh sysop@192.168.1.84 (password posys)

Connect to WIFI network

Rpi 3 rev B and Zero W have integrated wifi

Edit WIFI credentials

The file  /etc/network/interfaces should NOT be modified, as it’s overwritten at start.

Edit the file

sudo nano /boot/network.ini

To add your credential:

#
 # interfaces - setup your networking devices here
 #

auto lo
 iface lo inet loopback

allow-hotplug eth0
 iface eth0 inet dhcp

allow-hotplug usb0
 iface usb0 inet dhcp

# pipaOS Will automatically try to connect
 # to wireless ESSID "pipaos" passphrase "pipa123pass"
 allow-hotplug wlan0
 iface wlan0 inet dhcp
 wpa-ssid YOUR_SSSID
 wpa-psk YOUR_WIFI_KEY

High quality sound

Rasberry Pi have 3.5mm stereo jack output but the quality is pure crap, wondering why they even bother populate a jack.

So lets connect a cheap UBS sound card and check what appends

dmesg

sould display something like

[ 106.865142] usb 1-1.2: new full-speed USB device number 5 using dwc_otg
 [ 107.006372] usb 1-1.2: New USB device found, idVendor=0d8c, idProduct=0102
 [ 107.006387] usb 1-1.2: New USB device strings: Mfr=0, Product=2, SerialNumber=0
 [ 107.006395] usb 1-1.2: Product: USB Sound Device

[ 107.042816] input: USB Sound Device as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1-1.2:1.3/0003:0D8C:0102.0002/input/input1
 [ 107.105630] hid-generic 0003:0D8C:0102.0002: input,hidraw0: USB HID v1.00 Device [USB Sound Device ] on usb-3f980000.usb-1.2/input3

and

lsusb

will output:

 Bus 002 Device 009: ID 0d8c:0102 C-Media Electronics, Inc. CM106 Like Sound Device
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Create startup service : webradio

sudo apt-get install mplayer

mplayer `curl -w "%{url_effective}\n" -I -L -s -S http://direct.fipradio.fr/live/fip-midfi.mp3 -o /dev/null`

Webradio player script

create non returning script:

sudo nano /home/sysop/webradio.sh

while true
 do mplayer http://chai5she.cdn.dvmr.fr:80/fip-midfi.mp3
 sleep 1
 done

create init.d service: webradio

#!/bin/bash
 #webradio daemon
 # chkconfig: 345 20 80
 # description: mwebradioapp daemon
 # processname:webradio

DAEMON_PATH="/"

DAEMON=/home/sysop/webradio.sh
 DAEMONOPTS=""

NAME=myapp
 DESC="My daemon description"
 PIDFILE=/var/run/$NAME.pid
 SCRIPTNAME=/etc/init.d/$NAME

case "$1" in
 start)
 printf "%-50s" "Starting $NAME..."
 cd $DAEMON_PATH
 PID=`$DAEMON $DAEMONOPTS > /dev/null 2>&1 & echo $!`
 #echo "Saving PID" $PID " to " $PIDFILE
 if [ -z $PID ]; then
 printf "%s\n" "Fail"
 else
 echo $PID > $PIDFILE
 printf "%s\n" "Ok"
 fi
 ;;
 status)
 printf "%-50s" "Checking $NAME..."
 if [ -f $PIDFILE ]; then
 PID=`cat $PIDFILE`
 if [ -z "`ps axf | grep ${PID} | grep -v grep`" ]; then
 printf "%s\n" "Process dead but pidfile exists"
 else
 echo "Running"
 fi
 else
 printf "%s\n" "Service not running"
 fi

Install startup service

update-rc.d webradio defaults

Start service manually

sudo service webradio start

Check startup time and performance

Startup time with RPI 3 B: Startup finished in 2.602s (kernel) + 4.386s (userspace) = 6.988s

Not bad at all for a full featured computer with wifi and usb audio

Symptoms: the printer doesn’t want to print and ask for a toner change, no override available.

Easy procedure to reset toner counter: open the top cover, hold the * button for 5 sec (beside to keypad, not back-lighted, you can barely see it).

A reset menu appears and voila!

Fuck you Brother! My toner don’t need to be changed, my next printer wont be one of yours.

Source: https://printerthinker.com/brother-dcp-9020cdw/

Very basic feature, yet not present in Linux.

This very simple tool, xbanish, hide mouse’s cursor away when you start typing, and is restored back when moving the mouse.

Rationale: compensate a speaker response curve (gain and phase) on a audio file.

Just came accross REW (Room EQ Wizard) (Linux, Windows, Mac), it let you plot the output of your speakers, then create a filter to compensate the flaws.

Once you created your finely tuned speakers, Export-> Filter as text file.

Then, it’s time to process the audio file with this filter, using the amazing Sox:

sox -q input_file.wav output_file.wav `awk ‘$4==”PK” { gsub(/,/,””,$6 );val=$6;printf ” equalizer “val” “$12″q “$9}’ val=”%’6.3f” REW_filter.txt`

That’s it: you have a outputfile with the correct compensation for your just analysed speaker.

Of course this method is for non-real time need.

If you have access to a simple desktop mill/router, and you are not into mechanical part design, here is a very simple workflow:

Workflow

Sofware

You will only need free/open source program:

• Inkscape
• HeeksCAD and HeeksCNC
• LinuxCNC (optional)

Example

In order to illustrate this example, we are going to make a case for a nice Nixie Clock from PV Electronics

A simple Ikea-hack will do for the wooden box: DRAGAN 2-piece bathroom dish set, bamboo

The front panel is milled

And fitted in place

The 2 stainless steel feet are from Ikea again

Thanks Dan Heeks for the very good software.

Happy milling!

Files are available here.