555 Timer Project Ideas – Relay, LED, Lamp Driver Circuits

555 Timer Project Ideas and Driver Circuits

In this post, we will see various real-time projects to be developed using 555 timer working in monostable mode and astable mode.
These are the part of real-time application circuits. Based on these concepts we can develop numerous projects.
All the 3 circuits can be build quickly with minimal changes at output side. The part numbers are not given in the schematic for MOSFET, BJT and diodes.
Because we can use the generally available devices.

555 Timer Based Relay Driver Circuit: Monostable Multivibrator Mode

555_relay_driver_1In the above circuit, the 555 timer is in monostable multivibrator mode.  ie, single pulse generation mode.

  • It is the example of monostable operation in practical applications.
  • This circuit acts as a delay timer which is used to actuate a relay for a particular duration.
  • The delay time period is determined by the values of resistor and capacitor.
  • When the pushbutton switch is in open condition, the output will be low (approx 0.1V), so the relay coil will not be energized.
  • When the pushbutton switch is momentarily closed, the 555 begins its timing cycle;
  • The output goes high (in the above circuit it will be around 10.5 V) for a certain duration.
  • The duration will be determined by the following formula
    Tdelay = 1.1RC
  • The relay coil will get energized for the same time duration.
  • The diodes are used to prevent the current surges entering into 555 timer IC. The surge current may occur when the relay switch becomes ON/OFF.

555 Timer(Astable Multivibrator mode) Based Driver Circuits:

We know that, the 555 timer IC will work in two modes namely Monostable Multivibrator (Single Pulse) Mode and Astable Multivibrator (Multiple Pulse) Mode. The previous circuit is the example for driver circuit based on Monostable Multivibrator mode of operation.

The following circuits are the example for driver circuit based on Astable Multivibrator mode of operation.

In the LED blinking circuit, the BJT is used to amplify the 555 timer’s output current to drive the LED. The 1K resistor connected to the BJT is used to prevent excessive current from damaging the LED.

555_led_driver_Circuit

In the lamp blinking circuit, a MOSFET amplifier is used to control current flow through the lamp. If the lamp requires more current then a power MOSFET required.

555_lamp_driver_CircuitThanks for reading…. If you have any questions about the circuits please leave your comments below…

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