Diary of a geek

February 2014
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Andrew Pollock


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Monday, 03 February 2014

Yep, I'm still a geek

I did some soldering tonight, and it felt good.

I haven't really done much soldering since I built my cat water bowl monitor, and that's going back to the last decade.

My apartment building has an intercom-triggered release to the common front door, and the latch has been sticking a bit lately. It stuck today when Megan's Dad came to pick her up, and it stuck when Sarah came to pick up Zoe. It's annoying to have to trek all the way downstairs to let them in and then walk back up again. I decided I'd try and look into what the problem was today after everyone left.

A visual inspection of the latch showed nothing obvious, and no one else was home to push the door unlock button for me while I was at the front door, so I decided to have a look at how it worked from within my apartment.

I pulled the intercom phone off the wall and identified the two wires that got shorted when you pressed the unlock button, and shorted them by hand with a wire, and sure enough, I could hear the door solenoid releasing.

I was thinking to myself, "if only there was a way to trigger this with my phone". I have a RaspberryPi and an Arduino board at my disposal, but I didn't really want to risk frying either of them. Then I remembered that I had a BoArduino that I'd bought at the Maker Faire years ago, but never assembled. I figured it'd make a good sacrificial lamb.

So I rummaged around and found it, and busted out the 240v soldering iron I bought recently, but haven't used yet, and set about slapping it together. Man, it was fun. I had it half built before yoga, and finished it off when I got home. It even worked first go. I felt such a sense of accomplishment.

The problem is, my general electronics fu is so weak, I'm not sure where to go from here, and my multimeter needs a new battery. I think the voltage on the wire for the intercom is higher than the BoArduino likes. I'd naively thought I could just connect the two wires of interest, one to ground and the other to one of the digital I/O pins, and have the BoArduino act as a switch, but that's not working. If I wire it one way, it unlocks the door instantly, even with the board powered off, and if I wire it the other way, it seems to half power up the board just using the power of the intercom system. So I'm obviously doing something wrong.

My plan is to just have the BoArduino simulate pressing the button for 5 seconds at a time, every 10 seconds or so. Then I can be downstairs wiggling the latch to see what's up with it.

Or I could just place a maintenance request with the Body Corporate.

At least I had fun assembling the BoArduino, and now I have a spare one. It was nice to be able to go from problem to idea to execution in one night, even if the execution failed.

[05:46] [geek] [permalink]

Day 7, Kindergarten again

Today was a pretty quiet day, because Zoe had Kindergarten again. Nominally, I'm supposed to be doing Debian stuff today, but I had some work presentations I wanted to watch while I still had the chance, so I mostly watched them for four hours while blowing the cobwebs out of my development environment.

Zoe slept well last night and slept in a little bit to a whopping 6:30am. We got out the door at about 8:05am and by the time I'd got the bike trailer on the bike and made it to Kindergarten it was about 8:30am. Drop off went pretty smoothly.

I decided to go for a run after I got back home, so I banged out 5km. My running fitness has been a bit off of late, partially because of the heat, and partially because I just haven't been doing it enough. I need to get back up to 10km as soon as possible so I can try increasing the distance.

Both of Megan's parents work, and so I'm helping them out with picking her up on Mondays and Wednesdays. Today was the day of doing that. It was certainly an interesting experience having to wrangle two kids instead of one. Megan's a good kid, so it was no trouble.

To kill time, we went to the car wash, where I bought the girls babyccinos while we waited, and then we headed into the Valley so I could check my post office box.

After we got home, I attempted to do something I'd seen on Mister Maker. He basically squirted some PVA glue, some paint and some detergent into a cup and then mixed it all up and then blew into it with a straw until the bubbles rose over the top of the cup and pressed down on it with some paper. I used bubble mix instead of detergent because I figured it would have to be as good, but only Zoe's cup really worked as intended.

Then, despite much discussion about it, Zoe decided to suck on the straw instead of blow it and so I had to race her off to the bathroom to rinse her mouth out.

After that the girls played a bit more on their own, then Zoe wanted to watch TV but Megan didn't, so we painted a butterfly together and then Megan's Dad arrived to pick her up, and Sarah arrived not long after that.

I killed some time doing a spontaneous electronics project before yoga and that was my day.

[05:25] [life] [permalink]