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Topics - TomKeddie

Project logs / Dirty PCBs rocks at Vancouver Mini Maker Faire
Each year we do a large how to solder workshop putting about 120 people per day through assembling a simple led flasher.  Thanks to the affordability of dirty pcbs, it's also a fundraiser for us.

The design and instructions are all on github at http://

The faire and hackspace got a good write up in a local paper at http://

DirtyPCBs support / Are you paying DHL on receipt of your PCBs?
I've talked to Ian about this, it's not a big issue, I'm trying to see if this is worldwide or local to Canada - I think it is the latter.

On a $US29 PCB order inc DHL (which is a bargain BTW) I pay about $US14 on receipt of the order.  The duty/taxes is 12% which is minimal, DHL add about $US12 of processing fees.  This not limited to DP, the google reviews of the local office are full of similar complaints - they're over zealous on collection of duty to profit on the fees.  Fedex/UPS/Post will let through up to $US200 with no duty.

I'm curious if anyone else eg. Europe sees issues like this.  I'm not expecting Ian will add Fedex et al just for little Canada, but if there's a bunch of people seeing this it might be worth his while.
DirtyPCBs support / HOWTO : Panelising for dirty pcbs
One of the best features (other than the cool guys that run it) of dirtypcbs is that they choose to let you explore the capabilities of the board house without vetting what you submit. Some times that's garbage in garbage out (I've had to de-panelise boards with a metal shear). Some times the result is golden.

I've had two very successful runs at panelising using apeture scripting. ... -pcbs/3000



Project logs / Arduino Zero using a DP xQFP 50/80 prototyping board
I need more processing power than an AVR for an upcoming project so I ordered an Arduino Zero to take a look at the SAMD ARM processors.  Unfortunately my son coveted the box it came in, once the two were separated the Zero was never seen again.  I had separately ordered the processor part, I realised I could build a Zero using a spare DP xQFP 50/80 prototyping board.

The schematic is fairly simple, doesn't even need an external crystal ( ... ematic.pdf).  I was extra pleased when I realised the 1.27mm header fit the SOIC pattern on the board.

The bootloader is programmed using an Atmel ICE pod and openocd.  This is super easy using the Arduino GUI (instructions at  There is a PCB only version of the ICE available for $US35 ( ... L-ICE-PCBA).

Tools of the trade / PCB inspection stand for Chinese Magnifier
On the last hacker camp I picked up a magnifier with HDMI output on Taobao (or more expensive but no airfare needed http://

I find myself needing to peer into and under packages a lot, I got sick of holding the pcb and trying to focus so I laser cut this little stand.  It has two angles on it for different views.  I find it is especially useful for usb connectors.

Source files are at ... fier-stand

Project logs / MakeyMakey from Dirty PCBs, hell yeah!
MaKeyMaKey was a very successful Kickstarter from some smart guys at MIT ( It uses capacitive touch to stimulate USB HID devices using a Arduino Leonardo compatible programming environment.

We ran a workshop at VHS in Vancouver Canada last night building these using PCBs from Dirty PCBs. The design is open hardware, the Eagle files, bootloader and sketches can all be found on github (

I've contributed a layout photo, parts list and basic instructions at ... akey-makey.

I'm selling the leftovers at on Tindie at ... -pcb-only/

Project logs / Logic Pirate ICSP jig
This week at VHS (http:// we're building Logic Pirates in our SMD workshops.  The LP is an awesome little open hardware logic analyser design from DP.

The ICSP header is a tiny 0.05" pitch, I struggled with this a little until I came up with this top and bottom 0.1" jig (obvious in hindsight).

The LP is currently OOS at Seeed (http://, I'm selling the extra PCBs on Tindie (http://

The doco page on the LP is at http://  As above you need a pickit to program the initial bootloader and firmware image. The hex file can be found at http://

The Mouser project is at http://

Project logs / My kids are happy I shopped in Huaqiangbei

  • The lights are from the security buildings
  • The buttons are from SEG
  • The wiring is from SEG
  • The barrel connector is from one of the random component buildings

All purchased on the recent hacker camp trip.  Neither I nor my kids are sorry I went.

The circuit is a simple attiny driven toggle control/debounce for the button.  The led in the button flashes but is barely visible due to the heavy diffuser (removing it didn't work any better).
Project logs / SMD March - Tweaks to Ishan Kehribar's ethernet gateway

For our SMD March workshops I chose Ishan Keribar's Embedded Ethernet Gateway.  I added an FT230X and usb port with a Arduino uno style reset on CTS (230X has no DTR but avrdude toggles both).  I also used a SOB 5050 template to make cases easy to design.  By adding an 8MHz variant to the Arduino board config you can then download sketches like a Arduino - this is a little more accessible than a STK500.

Unfortunately I made two errors on the PCB, they're fixed by cutting tracks as seen in the photos.

The files are all at github including assembly photos, instructions and 8MHz/57600 bootloader. I make assembly easy by colour coding the strips of components to match the colour highlights in the photos.  I distribute the photo printed as standard 4x6 images.

I've been running workshops most months since September, it's a great way to get people interested in a hack space.  All the instructions and pcb designs are open source, feel free to repeat these at your hackspace.

I have some spare pcbs.  Given the errors I'm not selling them, but am open to offers of trade etc.  The version on github has the errors corrected but has never been fabricated.
Project logs / Simple USB Isolator

In one of the earlier SMD workshops I've running at http:// I managed to temporarily kill my new macbook pro when I plugged in a partcipant's prototype.  I revived it by removing the back cover and disconnecting the battery - all the time chanting to myself, must get a usb isolator, must get a usb isolator, must get a usb isolator…..

This is a nice simple soldering project that does exactly that, isolates your USB port from connected devices.  There are two input usb connectors, one carries data and power from the computer the other supplies power to the output.  The output comes from a 3rd USB A connector.  There is no power/ground/data connection between the computer and connected devices other than through the isolator chip.  This board has two grounds, two power supplies etc.

The isolator chip is an ADUM3160, it is most of the cost of this workshop – “The ADuM3160 is a USB port isolator, based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, this isolation component provides outstanding performance characteristics and is easily integrated with low and full speed USB-compatible peripheral devices.”

I did manage to get some samples from ... oduct.html.  We’ll be getting the ADUM3160 from Farnell/Element14, you can see more details on the isolator at http://

The isolator chip is limited to 12Mbps speeds, which are fine for development boards like Arduino etc.

PCB design is at ... b-isolator

I've put some on Tindie at http://
Tools of the trade / LED ring based illumination for american optical microscopes
Based on a recommendation in these forums I bought an American Optical 570 stereo microscope on ebay some time back.  I added the illumination shown below, I thought it might be useful to others.  I cut 3 pieces from a right angle piece of aluminium section, coated them in heatshrink, attached them to the lense with zap straps and then used tiny zap straps to attach LED car headlight rings (80mm, 100mm, 120mm - also from ebay).  They're powered through a pwm dimmer as the glare can get too much from very reflective surfaces.

General discussion / Hacker Camp Shenzhen April 2014 Participants thread
Name: Tom
Arriving: Hong Kong 2/Apr ~06:00AM
Attending: Days 0-3 and Maker Faire
Background:  In my mid 40s, trained in s/w, currently working in fpga, hackspace director, running monthly smd workshops at local hackspace.  Soldering since I was 8, first PC was a system 80 (trs-80 clone).
1) Meet a bunch of fellow hackers and have fun
2) Get better at soldering BGAs/QFNs and have fun
3) Stock up on switches/connectors/leds/wire/ etc for the next few years ;-)

(I've started this for people to voluntarily share information.  Pls share as little as you want, don't share enough for someone to find out where you live and when you're gone).