Understanding IC 555. Design note 3


We all used IC 555 in many applications. Why it is called as 555 Timer? There are three 5K resistors inside the IC that makes it as versatile IC for Timer applications. IC555 was introduced in 1971by the Signetics corporation as SE555 / NE555 and was called as IC555“IC Time Machine”. Later its CMOS version IC 7555 and Dual Timer IC 556 were introduced.
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555 Sound Transmitter. Unusual Design 2


Not satisfied with IC 555 design. Now I am going to exploit its Control voltage pin 5. This pin is used to give a controlled voltage to control the working of the Flip-Flop inside the IC. But if it is not used, it will be connected to the ground through a 0.01 disc capacitor. I am going to give a minute voltage into this pin. Let us see what happens.

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Timer with a difference. Unusual Design 1


You know the working of 555 Timer and a number of circuits using the IC 555 are available. But I am experimenting with this unusual design. It will give more time delay than the usual 555 Monostable design which gives only maximum 3 minutes. See the trick.

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Code Reading Lamp


Here is a dual colour lamp to read the code printed on the Transistors and ICs. The code and number printed on the black coloured body of these components are difficult to read if the room light is low since the printing is in faint colour or as impressions. This LED lamp is useful to identify the components easily.

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Clock Controlled Relay


You can switch on a load such as Water pump automatically at the required time through this Clock Controlled Relay. It uses an ordinary clock to trigger the circuit to switch on the load. The load remains on till it is switched off manually.


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Music Bell with In / Out Indicator


Here is a simple Music Bell with  In and Out indicator. The bell as well as the display turns on for 2 minutes and stop automatically. The circuit uses the popular ROM IC UM66 to generate music tone and a common cathode 7 segment display to show In or Out.

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