We have a nice big freezer in our laundry room that we use to store overflow and other “deep freeze” items that we don’t (or can’t) keep in our kitchen freezer. The door on the freezer needs a good shove to get it to close fully and due to the sometimes absent-minded adults and kids in our house it has been left ajar more than once. In one case we had a near complete defrost of the freezer and the loss of quite a bit of food.
After Sandi found the freezer ajar again a few weeks ago I decided that I needed to rig something up to alert us when the freezer door was left open. After some searching I found a simple timer circuit based around the famous 555 IC. I used the timer circuit in conjunction with a Normally Closed reed switch to make an alarm for the freezer.
Video
In the video I completely mixed up the whole open vs. closed switch and referred to the reed switch as a Normally Open, it’s actually a Normally Closed reed switch as explained below. Also, I said that the buzzer was rated at 80dB, it’s actually rated at 100dB.
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by Adam on October 8, 2010
I have a file server (AKA – Enterprise) that I have been using for the past 4 years or so. It’s a modest and simple setup, consisting of four 80GB IDE drives in a RAID 5 array. After the overhead (capacity of one disk) of the RAID array, and file system (NTFS) is taken into account it gives me a modest 223GB of storage space; 70GB of which is currently in use.
The RAID array on Enterprise serves as my primary “archival” storage, I put data there that I want or need to keep but that I’m not necessarily working on at at the moment. Enterprise also has a couple of other non-RAID drives that I use to store non-critical data.
RAID?
For an in-depth discussion of RAID you can check out the Wikipedia page. Simply, RAID stands for Redundant Array of Independent Disks. In a RAID 5 array the capacity of each disk is combined (minus the capacity of a one drive) to form one large disk. Parity is spread across the array (which is why you lose the capacity of one disk) and serves as the mechanism for redundancy. What this means is that any one of the four drives can fail and all I need to do is replace the defective drive; I don’t lose any data. In theory and in practice this is a great setup. In fact last year a drive in the array failed and fixing it was as simple as swapping the dead drive out with a new one.
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by Adam on October 6, 2010
In the past couple of weeks I have watched red light cameras go up in two intersections that I pass through on my way to and from work. It struck me that as law enforcement agencies and governments become more and more reliant on technology, the right of the people to use similar technology is increasingly being attacked.
This isn’t a gripe over red light cameras. No, it’s just me pointing out that since I can remember law enforcement agencies have been using audio and video recordings to protect themselves but arrest people on bogus charges for doing the same. It’s a gripe that as the government is constantly hiding its actions behind a veil of secrecy it seeks a backdoor into the private communications of the people.
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by Adam on October 2, 2010
W3 Total Cache (W3TC) is a great caching plugin. Using it on my modest server (512MB VM from Rackspace) I’ve seen both a dramatic decreased in page load times as well as reduced server load. However, it can be a chore to get it working correctly, I’ve had issues with the Rackspace CDN integration. Fortunately their support is top-notch and the developer listens to you when you submit a bug.
I like to play with the inter-workings of awaitinginspiration.com, which sometimes means that I break things and then have to fix them. I was messing around with the permalinks on the site a few days ago and didn’t notice that as a result I broke several posts, including my original iPhone Call Recorder post (the single most popular post on the site). The issue seemed to be somewhat sporadic, sometimes a problematic post would show correctly, and sometimes you’d get a message saying that the post could not be found. I was not sure what was going on. Eventually, like just about an hour ago, it occurred to my that the issue may stem from my permalink hi-jinks the other day and the W3 Total Cache plugin. Sure enough, it as a simple as clearing all the W3TC caches. Once the caches were cleared posts came up without an issue. So, the takeaway – if you use a caching plugin/system and make changes to your site; clear your cache.