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Screen Shot 2013-05-28 at 12.39.01 PM

This is a great project to do with your kids, grandchildren, students, etc. It’s a small circuit that uses a battery to light up two alternating flashing LEDs. My kids who are five and seven loved working on it together in the garage. They enjoyed doing a project with dad, and learning about soldering and electronic circuits. They show their LED flashing circuit to everyone that comes to the house. So if you want something to do with your kids that involves some hands on ‘maker’ activity this is good for you. Also, if you have kids in a class or group of any sort such as scouts or summer camp and want a building activity, this project would be ideal for you.

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Posted by: Glen | Tuesday May 28th, 2013 12:40 PM

Bio: Father of 2 boys, Long Term Tinkerer, Likes to spend time in the garage messing around. Welding, Electronics, Computers, etc.

Categories: Electronics, Fun & Games, Kids & Family | Comments

Comments

  1. Dean says:

    can you give a quick description of the basic principal why it flashes?

  2. Glen says:

    The circuit is a multivibrator circuit. The two transistors switch on and off in an alternating fashion which allows current to flow through each of the LEDs. When the circuit is first powered on, one of the transistors will turn on due to slight differences in the characteristics of the components. The first transistor to turn on, say T1, will have bring the collector, and base to 0 volts. The capacitor connected to T1 at the collector (C1) starts out with 0 charge, so acts like a short at the start – this keeps T2 off. Once the C1 capacitor starts to accumulate some charge, the C1 connection to T2 base begins to rise in voltage potential until it reaches the on point of T2. When T2 switches on, the collector of T2 goes to 0v allowing C2 to discharge to 0, T1 turns off, and the LEDs switch, until the reverse happens. You can adjust the speed of flashing by changing the 4700 ohm resistors and the capacitors.

    Hope that helps. For a way more detailed description look up multivibrator on Wikipedia.

    Thanks for checking it out!