TechGuise Posted January 18, 2013 Report Share Posted January 18, 2013 I'm trying to build a desk toy that has three small LED bulbs that come on automatically when the object is turned 90 degrees.Assumming that a small mercury switch between the bulbs and the battery would do the trick.... but I have no clue on following items. How do I determine what size bulbs to get and approx how many hours of life the battery would provide with a certain size bulb? (looking for something that would run a minimum of 10-20 hours)Is there another option besides a mercury switch (something a little more "shock resistant" would be nice)Where would I look to purchase these items (bulbs, switch)Pardon my ignorance, I am more of a woodworker than an electonics wiz. I appreciate any help I can get.. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted January 19, 2013 Report Share Posted January 19, 2013 A "Joule Thief" circuit can be used to power white LEDs from a single 1.5V battery.Mercury switches are banned in Europe. I don't know about the US. Fortunately, non-mercury tilt switchs are available. Quote Link to comment Share on other sites More sharing options...
TechGuise Posted January 19, 2013 Author Report Share Posted January 19, 2013 Thanks Hero! That helps a lot getting started. Looks like lots of instructions available on building that circuit.I guess I'm searching for the wrong thing... but I'm having trouble finding a place to purchase the small LED bulbs. When I do find them is there going to be a choice of voltages? Does it matter?Also could you tell me a search term to use when looking for the "non-mercury" tilt switches. I seem to be finding things used in thermostats. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted January 22, 2013 Report Share Posted January 22, 2013 LED stands for light emitting diode and is not a bulb but a semiconductor chip which produces light when an electric current is passed through it. The voltage across the diode is dependant what the chip is made of and the current flowing through it. You need to limit the current which can be done using a resistor or a circuit such as a the Joule Thief discussed earlier. A white LED has a forward voltage of between 3.2V and 3.8V and an AA cell provides between 1V and 1.6V so a boost converter is required: the joule theif does this too. Quote Link to comment Share on other sites More sharing options...
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