How to Make Adjustable On Delay Timer using 555 Timer IC

Introduction

In the world of electronics, timers play a crucial role in controlling the timing of various processes. An adjustable on delay timer is a device that can be used to activate or deactivate a circuit after a certain time delay. It finds applications in a wide range of fields, such as industrial automation, home automation, and robotics. The 555 Timer IC is a versatile integrated circuit that can be used in a wide range of applications, including timing and oscillator circuits. One of its popular applications is as an adjustable on delay timer. In this article, we will explore how to make an adjustable on delay timer using the popular 555 timer IC, BC547 and BC557 transistors, and a 10 trimpot. By following this step-by-step guide, you will be able to create your own versatile and customizable on-delay timer to suit your specific project requirements.

Introduction to Major Projects:

555 Timer IC:

The 555 Timer IC is a highly reliable and widely used integrated circuit that contains 23 transistors, 2 diodes, and 16 resistors on a small chip. It was introduced by the Signetics Corporation in 1971 and has since become one of the most popular ICs used by hobbyists and professionals alike.

The 555 Timer IC can operate in three different modes: monostable, astable, and bistable. In the monostable mode, the 555 IC functions as a “one-shot” timer, producing an accurate output pulse of a specific duration when triggered. This makes it ideal for applications such as timing circuits and debounce circuits.

BC547 Transistor:

The BC547 transistor is a popular NPN bipolar junction transistor (BJT) that is commonly used in amplification and switching applications. It has a maximum collector current of 100mA and collector-emitter voltage of 45V, making it suitable for low-power applications.

The BC547 transistor comes in a TO-92 package and has three terminals: the emitter, base, and collector. It can be used as a switch to control larger loads by providing the necessary current amplification and voltage switching capabilities.

BC557 Transistor:

The BC557 transistor is a complementary PNP bipolar junction transistor to the BC547. It has similar characteristics, but the current flows in the opposite direction. The BC557 is also commonly used in amplification and switching applications, where a PNP transistor is required.

Similar to the BC547, the BC557 transistor has a maximum collector current of 100mA and collector-emitter voltage of 45V, making it suitable for low-power applications.




10kΩ Trimpot:

A potentiometer, often referred to as a pot, is a three-terminal resistor with an adjustable center tap that allows for variable resistance. The 10kΩ potentiometer has a total resistance of 10,000 ohms and can be used to adjust the timing duration of the on-delay timer.

The potentiometer consists of a resistive track with a movable contact called the wiper. By adjusting the position of the wiper along the track, the resistance between the wiper and the other two terminals can be varied. This allows for precise control over the timing duration of the on-delay timer circuit.

How to Make Adjustable On Delay Timer
How to Make Adjustable On Delay Timer

Circuit Diagram of Adjustable On Delay Timer

This project can be designed using a few basic components. The circuit diagram of this project is shown below.

How to Make Adjustable On Delay Timer Circuit Diagram
Adjustable On Delay Timer Circuit Diagram




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Components List of Adjustable On Delay Timer

Following is the list of all components used in this project:

  • 1X 555 TIMER IC
  • 1X BC547 TRANSISTOR
  • 1X BC557 TRANSISTOR
  • 1X 1N4148 DIODE
  • 2X LED
  • 1x 1uF CAPACITOR
  • 1x 100uF CAPACITOR
  • 1X 10K TRIMPOT
  • 4X 1K RESISTORS
  • 2X 10K RESISTORS
  • 1X 470K RESISTOR
  • 1X 12V RELAY
  • 1X 2 PIN TERMINAL BLOCK
  • 1x 3 PIN TERMINAL BLOCK
  • 1X PERF BOARD
  • JUMPER WIRES

Step by step connections of Adjustable On Delay Timer

Step-1: Insert a 555 timer IC and a 2-pole terminal block on board. Connect positive and negative of power supply to the terminal block. Now connect pin-1 of 555 IC to ground and pin-4, pin-8 to positive supply. Also join pin-6 and pin-7 of 555 IC together. Take a 100uf capacitor and connect its positive side to pin-7 of the IC and negative to ground. Now connect 1k resister to pin-7 of the IC.

Step-2: Now insert a 10k trimpot and connect its pin-3 to positive supply. Also join its center pin and pin-1 together. Now connect the remaining pin of 1k resister to pin-1 of the timpot.

Step-3: Now insert a BC547 transistor and connect its pin-3 to gound, its pin-1 to pin-3 of 555 IC. Take 1k resister and connect it from pin-2 of BC547 transistor to ground. Also connect a 470k resister from pin-2 of the IC to positive supply. Now take a 1uf capacitor and connect its negative to pin-2 of BC547 transistor, positive side to positive of the power supply.

Step-4: Insert an LED and a 1k resister and connect LED's cathode to ground. Connect LED's anode to 1k resister and other side of resister to positive supply. Now take a 10k resister and connect one side to positive supply and negative side to pin-2 of 555 timer IC.



Step-5: Now place a BC557 transister and connect its pin-3 to positive supply. Take one more 10k resister and connect it to pin-2 of BC557 transister. Also connect its other side to pin-3 of the IC.

Step-6: Now place a 12v relay and connect its coil pin-2 to ground. Now connect its coil pin-1 to pin-1 of BC557 transistor. Now take a 1n4148 diode and connect its cathode to pin-1 of BC557 transistor and anode to ground.

Step-7: Now take one more LED and a 1k resister. Connect LED's cathode to ground and anode to 1k resister, while the other side of 1k resister will be connected to pin-1 of BC557 transistor.

Step-8: Now finally, insert a 3 pole terminal block and connect its pin-1 to normally open, pin-2 to common and pin-3 to normally close pin of the 12v relay.

Conclusion of Adjustable On Delay Timer

In conclusion, the adjustable on delay timer we have discussed in this article allows for precise timing control in various electronic applications. By utilizing the 555 timer IC, BC547 and BC557 transistors, and a 10 trimpot etc., you can create a reliable and adjustable on delay timer circuit. With this knowledge and practical implementation, you can now integrate an adjustable on delay timer into your electronics projects, opening up possibilities for automation, precise timing, and enhanced functionality. So, get your components ready, solder your circuit, and immerse yourself in the world of adjustable on delay timers.

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For more project and circuit diagrams, you can go through the Schematics in the main menu where you can find many interesting projects and circuit diagrams like audio amplifier circuits, voltage booster circuitbattery charger circuit and timer circuits etc., which are all beginner circuit projects. Feel free to check them out!

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