Hobby Circuits

Astable Multivibrator is also called ‘Free Running relaxation oscillator’ and is commonly used to create square wave generation. As a hobby circuit, it is used as LED running circuit.

Components Required

Light Emitting Diodes : 2

Resistors: 470 – 2 and 47K – 2

Capacitor: 10µf – 2

Battery: 9V

Transisitor: BC548 – 2

Figure shows circuit diagram of a Astable Multivibrator.

Astable Multivibrator with LED | LED Running circuit | Fancy LED circuit

The Resistors used in the above circuit are very common in the market.

Capacitor values are not mentioned in the above circuit because you can use any amount of capacitors (both should be same value). As capacitance changes, the delay between ON and OFF of LED’s also be changed. Use capacitors of 10 µf for standard delay.

The working principle behind the Astable Multivibrator is, turning ON and OFF of transistors, ie, when transistor Q1 is ON, the Q2 will be in OFF condition. The delay between ON and OFF of transistors are determined by the capacitors.

Need any Assistance? Have any doubts/comments on the construction or working? Feel free to add it as comment below.

Thanks for reading and sharing 🙂

Today, We are discussing about a circuit which is suitable for middle school and high school students. It is funny and involving hand-on learning.

About the Simple Wire Loop Game.

This game may familiar to you. It is available in market or on some carnival fests, it is introducing as a competition. Its is simple eye-hand coordination game involving a wire on hand and a small hole. The game is, the player need to hold the wire and attempts to guide it through the small hole. When ever the loop touches the sides of hole, Game will finished and a RED LED will starts lighting. We can improve its hardness by reducing diameter of the hole.

Wire Loop Game Construction Using 555 IC

Here, The player have to touch the point C, via the hole B without touching its sides, using the point A ( Should be covered its touching side by an insulator). While successfully touches the point C, you wins the game and a GREEN LED will blow. If the handle A touches on side of B, the ckt will be OFF and and a RED LED will start lighting.

It is best to reduce the diameter of B (hole) to make the game more interesting. 🙂

Working of Wire Loop Game.

The main component of this circuit is a 555 IC. The 2nd pin ( Trigger ) of IC 555 is connected to +ve and pin 6 ( thresh hold) is connected to –ve. While the circuit is on, IC output will be on OFF state. and RED LED lights. While getting –ve pulse on pin 2, circuit will be triggered and GREEN LED will start lighting. At this time, if pin 6 gets a +ve trigger, the circuit will be OFF.

Update: You could also give a little electric shock if someone failed the game.

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If you have any doubts/comments on the construction or working of this game, Feel free to add it as comment below 🙂