On Standing Brooms

The other day the wife-unit showed me a picture of a broom that was standing on its own by its bristles. She said that people were posting them on Facebook saying that it was caused by a phenomenon associated with the Spring Equinox.

A bit dubious, I ran to the laundry room and grabbed a broom. The first broom I tried to balance didn’t work because (I thought) the broom was newish and the bristles were too stiff and it was too small. I went back and grabbed a different broom and tried it. The second broom had a bigger head and is older and more worn than the first. Without too much trouble I was able to get that broom to stand up on its own.

This is not trick photography nor is it “Photoshopped.” The broom is actually standing on its own. The only thing that was done in Photoshop was to re-size the picture so it would fit on the page. You can get the original, complete with EXIF data here.

I had originally thought that the first broom didn’t balance because it was too new and the bristles were to stiff. My theory was that an older more warn broom would have softer bristles that would spread out to support the broom. While this may still be the case, after looking at both brooms, I found that the older broom actually has stiffer bristles than the newer (green) one.

In fact the newer broom (a dollar store special) has significantly softer bristles than the older one; it can’t even support its own weight. I also think that the size of the broom head may play a role in being able to get it to balance. I think you actually need a broom that has bristles stiff enough to hold it up but not so stiff that they don’t spread out to support the broom laterally.

So What?

Broom standing seems to be a relativity recent offshoot of the old Equinox egg balancing hoopla. The claim with the eggs is that during the Spring Equinox there is some special gravitational mojo going on that allows one to balance an egg on its end. In reality, with a little trial and error you can get an egg to balance on its own any day of the year. It has noting to do with the Equinox. The standing broom is the same thing. It’s a cheap parlor trick. Noting more.

A few things to keep in mind:

  • None of the planets, not even the Moon, exert enough gravitational force to cause eggs or brooms to stand on end.
  • You’ll note that the Spring Equinox for 2012 is March 20th. If broom standing is related to the Equinox how then was I able to get my broom to stand on March 10th?
  • If you look at my picture above you’ll note that it’s showing the profile of the broom and on the left side you can see bristles sticking out that look to be helping prop the broom up. This might be why all the pictures that I’ve seen show the face of the broom, rather than the profile.
  • I actually had to work to get the broom to balance. Unlike what many are claiming, it didn’t just stand there when I let go of it, it was more like playing a game of Jenga.
  • I’ve heard that new brooms work best but I had better success getting an older broom to balance.

I think that this kind of stuff is important to debunk. It’s a fun trick but that’s it. It’s just just a broom balancing on its bristles. There is no need to invoke pseudo-scientific drivel to explain this “phenomenon” and to do so is disingenuous.

I See Your Standing Broom and Raise You A Floating Broom

After I posted my standing broom picture to my Facebook with a short explanation a friend replied: “Call me when you make it float.”

Challenge accepted:

DIY Power Supply

Adjustable Power Supply

Retail an adjustable power supply like this would go for ~$50. You can make one for ~$10. If you salvage parts from stuff destined for the trash, you can make one for free-ish.

Everything with a red arrow pointed at it was salvaged from old hardware, mostly an old TV set.

This is how you recycle.

The power supply uses the LM317 voltage regulator. The input voltage can be anything from 9v to 30v. The output is adjustable from 1.25v to within a few volts of the input voltage. A good guide to follow for making your own can be found here: http://www.ladyada.net/library/equipt/diypsupp.html

Motorized Pinewood Derby Car

I woke up the day of the Pinewood Derby race and decided that I wanted to run a car in the “outlaw” class. Using spare parts I had lying around I made a remote controlled Pinewood Derby car in about five hours.

The car would have done really well (especially since the CO2 car malfunctioned on both official runs) except for a couple of issues. On the first run the rubber band on the driver’s side wheel came off and wrapped around the axle, jamming it. On the second run the limits of the cheep transmitter/receiver became grossly apparent as I had to chase the car down the track to keep it going.

In case your wondering (and why wouldn’t you be?) the axle, motor, gears and belt came from an old printer. The wheels were cut from a piece of acrylic, and the transmitter/receiver parts were “borrowed” from a dollar store RC car.

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2012 – Pinewood Derby

This year the youngest child-unit participated in the Cub Scout’s Pinewood Derby. He did all the design, build, and paint work. He outsourced some of the electronics work to me.

The light is a BlinkM programmable LED. It was programmed (per the child-unit’s request) to blink like a police light.

The BlinkM light was powered off a 9v battery that was housed in the “bed” of the car. Because the BlinkM can only take a maximum of 5v a 7805CT (that was salvaged from an old TV set scanner) was used to regulate the 9v coming from the battery to a safe 5v.

While his car did not do very well in the races (5th place was the best he got in any of the heats) it was easily the coolest looking. And it was the only one that had working blinky lights!

Here is a video of the car racing (sorry for the shaky teenager-shot video):

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Made – STOP Sign Binder

I first came across the metal binder idea from Instructables. I then came across the traffic sign binder via Make. Having a middle schooler who can’t seem to keep a binder intact for longer than a week the metal binder idea appealed to me.

The Build

At first I was going to use sheet metal but came across an old STOP sign at a construction recycling center. The rest of the materials consist of a piano (continuous) hinge, a donor binder, and some rivets.

Final Thoughts

As mentioned before – if I make another one I’ll use a jig so that the cuts with the jigsaw are straighter. Also, as can be seen in the picture above, I used washers to makeup for the hinge holes being too big for the 1/8″ rivets. I have some doubts about how robust this will be. For now I’m going to see how it works but I may need to either use something else besides washers or track down bigger rivets.

Freezer Door Alarm

UPDATE

The freezer door alarm has been working great, except for one minor issue. When loading the freezer it was often open for more than the 27 seconds the timer was set for. So while loading the freezer (or staring blankly into it deciding what you wanted) you’d either have to close the freezer door to reset the timer, or suffer through the buzzing.

Not wanting to increase the length of the timer, I added a momentary reset button. Now if you want to have the freezer door open for longer than the timer allows, all you do is press the reset button which gives you another 27 seconds to do what you need to.

The reset button is a Normally Closed button that is wired between the battery and the timer; just like the reed switch is. When pressed it cuts power to the whole timer, just like the reed switch does. Since it’s a momentary button as soon as it’s not being pressed power to the timer is restored, turning timer back on. This allows you to reset the timer without the risk of leaving it in an off state.

I did not update the schematic shown below but to add the reset button just place it in-line with the reed switch. The pictures below show the reset button (which was salvaged from an old computer case) added to the alarm.

END UPDATE

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.

Schematic

Reed switches are really cool. In a Normally Open reed switch two contacts are aligned very close together in a glass vial, so close that when a magnet is placed near the reed switch, the contacts touch, completing the circuit and allowing current to flow. However, I needed the reverse, I needed a reed switch that completed the circuit (i.e. turned it on, let current flow) when the magnet was taken away from the reed switch. This can be done any number of ways but the simplest is to use just use a Normally Closed reed switch.

The whole Normally Open, Normally Closed thing can be a bit confusing. In the case of reed switches they are in their normal state when a magnet is too far away to have an effect on them. So a Normally Open reed switch does NOT complete a circuit when the magnet is removed, where as a Normally Closed reed switch DOES complete a circuit when the magnet is removed.

In any case I used a Normally Closed reed switch as I needed the circuit to be completed (the timer to be turned on) when the magnet was removed (i.e. the freezer door was left open).

The Build

The buzzer I used can run off 3-12VDC and is rated at 100dB at 12VDC, I’m not sure what the dB level is at 9VDC but it’s plenty loud enough to be heard even on the other side of the house.

The alarm works great, the reed switch is sensitive enough (the magnet needs to be within ~4mm to open the reed switch and turn off the alarm) that the door has to be purposefully closed in order for the alarm not to sound. The buzzer is loud enough that we can here it from any room in the house and when the freezer door is closed (which is most of the time) the circuit does not draw any power, so the battery should last a good long while.

Parts List

Part Supplier Part # Quantity Price (ea) Total
555 Timer IC DigiKey 497-1963-5-ND 1 $0.50 $0.50
555 Timer IC Socket DigiKey ED2680-ND 1 $0.26 $0.26
470 ohm resistor DigiKey CF14JT470RCT-ND 1 $0.08 $0.08
33k resistor DigiKey CF14JT33K0CT-ND 1 $0.08 $0.08
100k resistor DigiKey CF14JT100KCT-ND 1 $0.08 $0.08
1M potentiometer DigiKey CT2271-ND 1 $1.55 $1.55
220uF capacitor Digikey P13131-ND 1 $0.71 $0.71
0.1uF capacitor DigiKey 493-1329-ND 1 $0.25 $0.25
Green LED DigiKey 67-1063-ND 1 $0.41 $0.41
Red LED DigiKey 67-1069-ND 1 $0.42 $0.42
9VDC buzzer DigiKey 668-1029-ND 1 $4.51 $4.51
Reed switch DigiKey 59140-040-ND 1 $4.81 $4.81
Reed switch magnet DigiKey 57140-000-ND 1 $2.86 $2.86
9V battery clip DigiKey 377-1549-ND 1 $1.20 $1.20
Enclosure (mint tin) Supermarket check-stand Cinnamon 1 free(ish) free(ish)
TOTAL $17.72

Windows 7 Remote Desktop Scrollbars

A couple of weeks ago I upgraded to Windows 7 and I have to say that compared to Vista it’s actually a usable operating system and I’m quite enjoying it.
However, there was one issue that was bugging me – I have several remote desktop sessions for various servers set and saved to open in a 1024×768 window, in Windows XP those RDP sessions worked great.

Windows 7 seems to have a bug where, no matter what the windows size it set to the window opens slightly to small, causing you to have to stretch the window to get it to the proper size.

Windows 7 Remote Dekstop scrollbars

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Label Maker Ripoff

Is there a legitimate reason why label makers leave such a huge margin between the text and the ends of the label; no matter how much text is printed? I’ve seen this on every label maker I’ve used. The one used to make the labels pictured is a Brother PT-1000. You can configure the PT-1000 to use a smaller margin but it still prints the same 1″ tail on either one side of the label. The only thing setting a smaller margin (either 1/2″ or 1/6″) does is print dots as a guide to cut the excess label off.

Seems like an awful waste and a good way to keep label refill sales going strong.

Update: July 27, 2010 – I added an image showing how a label comes out of the PT-1000 with the smallest (1/6″) margin set and corrected an error in the above text.

Label Maker Ripoff

Label Maker Ripoff

Label Maker Ripoff

Monster Cable – Monster Rip-off

Companies like Monster Cable were walking a fine line with their high priced analog cables because most people can’t tell the difference between gold plated, gas injected cable and coat hanger. But when the switch to digital started Monster was quick to cross way, way over that line by duping people into thinking they needed an overpriced cable to connect their HD devices. The problems is, HDMI is a digital signal and unlike analog signals (like composite video), it’s either there or it’s not. So, whether you have a $250 cable or a $6 cable your TV is going to look the same.

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iMac Digital Picture Frame

iMac Digital Picture Frame

Ok, there are a gazillion DIY digital picture frames out there, this is nothing new. I figure I’d share it though because it shows a good use for outdated hardware but it also serves as documentation so six months from now when I’m asking myself “how did I do that?” I’ll have somewhere to look.

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