Friday, October 31, 2014

Reboot! Join a hacker space.

How time flies!

It has been a year since my last post. The project has been at a complete standstill while other things happened in my life - like repapering the kids' rooms and restoring the front of a rotting caravan.

All the while I have longed to continue the project but continually failed to actually *do* something. Eventually I decided to join our local hacker space Hal9k. I get around-the-clock access to the facilities, and - more importantly - club night every Thursday. Tonight is the third time I attend - and I love it. The other members are doing all kind of great (and weird) things, and are ready to tell about their projects. I have added a repeating weekly appointment to my calendar, so from now on Thursday night is dedicated to the AccessThing project. Great!

So far I have spent the time remembering where I left the project a year ago, assembling my HDMIPi screen, and finally tonight made an LED blink when connected to the GPIOs of the Raspberry Pi. I really like that the pins can be manipulated by writing to device files under /sys/class/gpio/.
My HDMIPi connected to a breadboard - and my first LED connected to GPIO25.

Two weeks ago I also decided to order another kind of MOSFET. The IRL540N I had bought last summer needs a higher gate-source voltage than 3.3V (from the GPIOs of the Raspberry Pi). So I ordered a roll of 50 low voltage IRL2502 MOSFETs from eBay. When they arrived today I had to pull out my magnifier - they are kind of tiny: 2.9mm x 2.3mm including the legs! Max ratings are 20V Drain-Source and 4.2A (at a higher Gate-Source voltage), so they should easily handle the 12V/220mA I need to drive the Ruko/Abloy EL582 solenoid lock. But it might take a little practice to solder them.
IRL540N and IRL2502.

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