There are three doors in my house that open outwards, and I have personal experience how easy it is to walk into the edge of one of them in the dark. After doing this a few times, I decided to build a device for providing a flashing LED embedded in the edge of the door to warn you that it is open.
This is really simple to make, and saves getting blood on the bedroom carpet
This is really simple to make, and saves getting blood on the bedroom carpet
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Signing UpStep 1: Step 1. Make the circuit
The circuit came from my stash of ancient electronics relics, I have no idea where it originated. It will run off a single AA penlight dry battery, although I used a bigger C size battery. The original unit has been running in my house 24/7 for around 5 years so far with no sign of giving up yet.
I etched the circuit board myself and soldered the parts to it. I used BC107 transistors for TR1 and TR2, and a 2N3906 pnp transistor for TR3, but pretty much any npn transistors will do for the first pair, and any pnp for the third one. The LEDs I used are 5 volt types, but I’m not sure that they need to be, and I suspect any standard LED (and any colour you like) would work just fine.
I etched the circuit board myself and soldered the parts to it. I used BC107 transistors for TR1 and TR2, and a 2N3906 pnp transistor for TR3, but pretty much any npn transistors will do for the first pair, and any pnp for the third one. The LEDs I used are 5 volt types, but I’m not sure that they need to be, and I suspect any standard LED (and any colour you like) would work just fine.
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You and your crooked nose are safe with us!
Sincerely,
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We also like your crooked nose.
Nicely done.
This instructable is only useful at night, when there is little light, exactly the same as when you have the door closed and covering the switch.
It could at least be used to have it turned off when it sees light, i.e. when the door is open during the day, then the LED would only light when the door is closed or its night time. It would be worthwhile even if using a reed switch so if the door is open during the day the light won't shine.
I guess this is getting more complicated than its worthwhile, Its a great idea, It looks like it works well and the author doesn't seem to have any problem with battery life. well done!
(Bien dicho bstevenson1!! Cada uno hace de su tiempo lo que se le canta!!!)
There is also a circuit from Radio Shacks optoelectronics projects book I use from time to time that is a dual led flasher, that uses 2 2n2222 transistors and I think 2 2n3906's. (Like a school bus or railroad crossing flasher). Maybe useful to someone.
Stop walking around in the dark, would probably help.
much fun being burned alive either
represents just as much a hazard as an open one...now
lets consider the stairs...assuming you have stairs that is....
ie darkness, staircase...fall...broken neck....yep id happily
take the open door and broken nose : )....lets have some
LEDS on that staircase please...flashing ones. Now youve just
picked yourself up from the fall down stairs, broken neck takes
your mind of your broken nose...still pich black and you bump into
someone !!! well you get my drift lol...just turn on the light
walking out of the window solved lol : )
I know it's not got that tech-cool, but I'm sure it'd do the job.
Seriously!
Let's say you have your saber saw welded to your oak bed leg.
You get too close and it turns on, the sound would alert you of impending pegleg disaster.
This would be great for blind people who couldn't see a red light.
:p
Of course you could also just paint the legs in 5 minutes and then use the remaining build time to make something else entirely... and that could be far more power-tool hungry than this. :D
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Make that "If attached with the right adhesive it also has advantage of being easily removed."
Why don't you just get rid of your doors. As you've got only three I guess you place is somewhat small : you wouldn't believe the feeling of roominess when you trips the doors of a small apartment !…
OK , I'm joking, but it is true : I don't have doors in my house (except a sliding panel for the bathroom).
Low battery voltage leads to more frequent flashes. It is easy to see that the battery needs to be changed. I am using BC547c and BC557c and a high power red led. I used a 470uF capacitor instead of a 100uF. Because the 10k resistors where out of stock I am using 12k, these work as well. The circuit operates from nearly 1V up to 6V. If you go above 3V the flashing frequency gets very low and the led starts glowing right before the flash pulse. Best operation is with 1.5V alkaline cells as grizelli recommended.
I have'nt made any long term test, because I just built it one day ago. It runs on a 1.1Ah NiMH battery since then, without problems.
The way the shematic was drawn reminds me of German magazine called Elektor or Elrad ...