Apr 23

I got my sticky hands on some very nice vintage LED-displays, and some days ago i got a pack of nice prototype-PCB’s from eBay, so of course i had to make two small test-boards for these displays :D

This one is for 4 pcs. of TIL311, intelligent Hexadecimal display (shows 0-9, A-F)

TIL311 LED Display

TIL311 LED Display


The next board is for a DL1416 display. It can display all numbers and some Alphanumeric digits. It has a 7-bit Data-bus.

DL1416 LED display

DL1416 LED display


The plans for them? Well i have enough of both types to warrant the time needed to layout a design for a very limited-edition wristwatch :)

Nov 23

EDIT: Read bottom of post!

I have been toying around with GSM modems for some time – working on the Rotary Cellphone project, i settled on the SIM900-module from SIMCOM.

Milled SIM900-board

Early in my quest, i mistakenly read, that the SIM900 was Quad band, and the SIM900A was Dual band. As I decided that i did not need the Quad-band capability, i ordered the SIM900A-modem, as it was a few $ cheaper.

Ordering the first module from far east (AliExpress) my choice was the SIM900A model. I milled a breakout-board for the GSM-module, soldered it on, and everything “seemed” to work, but i could not register the modem on the Danish GSM-network. It acted like it was locked to a specific GSM-vendor.

The modem being brand new, ruled out the option that someone else had a go at it, so what was happening ?

I trawled the documentation at SIMCOM, and couldn’t readily find any information on what the differences between a SIM900 and a SIM900A-model were.

Some helpful people at the local Hackerspace mailing-list soon found the culprit (i guess their Google-fu was better than mine)

The SIM900A-model is locked to these regions:

  • China
  • India
  • Singapore
  • Malaysia
  • Thailand
  • Indonesia
  • Cambodia
  • Vietnam
  • Laos
  • Burma
  • Brunei
  • Philippines
  • East Timor

Official documentation is mirrored here: SIM900A Supported MCC List V1.00

Why SIMCOM makes this module, locked to specific regions, i do not know, if you have any idea why, please leave a comment.

User [] had luck upgrading the Firmware on his module – you can read about his findings here - i have not tested the firmware file, as i destroyed my 900A-model in frustration and anger.

Jul 13

Finally got time to shoot a vide of the cube working, what do You think ?

Feb 08

First initial testing, after fixing some minor errors i made in the layout (Swapped RX/TX, not first time) and swapped D & S on the Fets. Grrr…

Feb 04

I’m in the process of building a 5x5x5 LED Cube like many others. The firmware is designed by [SiGNOUT] and [knielsen] from the local Hackerspace.

Their Cubes use a Seperate Arduino, and TLC5940 LED-drivers in TSOP housing. I would like to push the limits on my version of it, so i ordered the TLC5940 and Atmega328P in the smallest possible cases available. I would like to try BGA some day, but BGA requires more than dual layer PCB, so that’s impossible without professional PCB’s. The Atmel is 4mm² and the TLC5940 is 5mm².

The board is 2-layer and has holes through plated chemically. It is made on our Protomat & Minicontac II.

Here’s some pictures of the milled PCB:

Some more pictures in the Gallery

There’s pictures of another PCB in the folder, an Infrared LED exposure device for Playing with a Laser printer.

Dec 17


I am in the process of installing a Nexus 7 Tablet permanently in my Car – Using it for Navigation software and playing music.

I need to be able to tell the Nexus 7 to pause playback of music, and go to sleep. The easiest and most simple way is to touch a NFC tag to it, that tells it to do just this (Using a combination of NFC Task Launcher & Tasker)

But, how to enable the tag at will ?!

Solution: Put a CMOS switch in series with the antenna of the tag – this way it will only be readable when i tell it to!

A good solution is the 74HC4066 or even the DY411DY, but those are just too big an complicated. Why not resort to a single CMOS switch – Enter the 74LVC1G66.

A small SOT353 device that does it all, albeit a bit small for most soldering irons, but nothing my Weller WD1000M can’t handle.

I drew up a board in Eagle cad and milled a PCB. It didn’t work in the first try, it seems I damaged the RFID chip when removing it from the blob of glue inside the tag, so next chip i mounted sits on a big glob of glue, no need to risk damaging another chip!

I the second try, it works perfectly! – The chip needs a supply voltage of 3,3 or 5V and a logic high signal to trigger the Tag “ON”


Here is a Video of it in action!:


Attached is the Eagle files for your perusal.




Feb 12

Recently, i purchased a big lot of Philips ZM1000 Nixies, and needed a test PCB to test out if all was good – i got sockets for a number of the tubes, so i settled on making a PCB with the correct socket, so I easily can test them.

Being fond of the Arduino, i just thought, why not make it an Arduino shield – this way it’s a nice compact solution, powered by the USB-port, and no extra cables needed.

I earlier on aquired one of the real nice high voltage supplies, perfect for nixies from Taylor Electronics

So i made a single PCB that fits the small power supply module, a socket for a 74141 Nixie driver, and a socket for the ZM1000 tube.

I milled the PCB on our PCB milling machine in the local hackerspace where i frequent, Labitat

I did not mount all the headers on the finished PCB, since they are not in used. The use of stacking headers are a little waste, since there is no way I can mount anything on top of the Nixie PCB, but they make the PCB headers more mechanically stable, since they are soldered on on the bottom side of the PCB.

A small video of the circuit in operation, running a simple counting program, testing all digits: Youtube



You can get the Eagle PCB files for the project here: ZM1000_Shield

Jan 24

Wow, i didn’t expect being featured on Hacked Gadgets with my *ugly* LCD ribbon connector hack, but what the hell.


Thank you guys!

// Per.

Jul 17

Programming Arduino Mini’s and similar units with no on-board USB requires a USB/RS232 adaptor for the computer (unless you really have a RS232 port on your PC, then you need a MAX232 Level Translator)

I scoured eBay to find the cheapest converter, and i found this.

Looking a bit further, for a bit more you can get this that is housed in a nice case [link]

These units use the CP2102 USB to TTL converter chip [Datasheet]

Funnily enough, the RST pin is brought out, this pin, when taken low will make the CP2102 go into low power mode and de-enumerate. You can wake up a computer in sleep mode by toggling this pin.

But i do not need to do this, i’m more interested in using this for programming Arduino’s.

Arduino’s use the DTR pin for the reset of the bootloader, and this pin is fortunately at the very corner of the QFN chip so it’s easy to get to.

Removing the pullup resistor [R2] and soldering a small wire from the DTR pin to the RST pin brings out the DTR pin for Arduino programming.

I cut the original trace for the RST pin on the underside of the PCB, but i was too lazy to take a picture of that.

When i was modifying the unit i replaced the header pins too, since they looked like they were soldered on the wrong way round, they don’t really fit in the cutout of the case…

Some pics of the modification:


Jun 22

Hi folks. A fellow member in Labitat, Peter assembles electronics for Makerbot, at the moment he is making:

  • Makerbot Motherboard v2.4
  • Extruder Controller v3.6
  • Stepper motor driver v3.3
  • Mech endstop v1.2


I bought a set of electronics for my RepRap Mendel that is in the making at the moment.

Peter was foresighted and fitted an Atmega328p instead of the bog standard Atmega168 that is a bit old today, this way the EC will have room for improvements which is not bad!

The standard ReplicatorG software cannot program the Atmega328p at this moment, but you can modify it by compiling the code your self, and add something in the firmware.xml – but i don’t see this as a good solution, since you won’t get updated firmware from Makerbot this way.

If you want to program your Extruder Controller fitted with a Atmea328p, follow this guide and it will work out for you:


A beginner’s mistake was writing

scons -f SConstruct.extruder
scons -f SConstruct.extruder port=/dev/SERIALDEVICE upload
It didn't work because i had not read all the instructions. It defaults to compiling
the code for the old Extruder Board 2.2 and not the Extruder Board v3.4
So running this made it work:
scons -f SConstruct.extruder platform=ecv34
scons -f SConstruct.extruder flatform=ecv34 port=/dev/SERIALDEVICE upload
This compiles the code from source to your Atmega168-fitted boards. To compile for
the Atmega328p you need to do these changes:

inside the /G3Firmware/v2/src/Extruder/ there is a SConscript file, edit this.
if platform == 'ec36':
platform = 'ecv34'
default_baud = '19200'
Edit it so it says this:
if platform == 'ec36':
platform = 'ecv34'
default_baud = '57600'

Further down the file change this:
elif (platform == 'ecv34'):
default_baud = '19200'
So it reads like this:
elif (platform == 'ecv34'):
default_baud = '57600'
With these changes you can compile for the Atmega328 ;-)