Simple Automatic Doorbell Light Circuit

This automatic doorbell light circuit is like a helpful friend for your doorway.

When someone rings the doorbell, it automatically turns on a light right next to it.

This makes it super easy to find the button especially at night or in the dark.

So you can greet your visitors quickly and safely.

Circuit Working:

Parts List:

This circuit utilizes a 6V battery operated doorbell light that can be paired with an existing AC230V doorbell in parallel.

When the doorbell switch is pressed the bell rings as usual and the AC mains supply available across the doorbell is directed to the circuits input through an opto coupler IC1.

When IC1 conducts it triggers a monostable circuit based on the 555 timer IC2.

This action causes the high brightness white LED D1 at the output of IC2 to turn on briefly.

This feature proves particularly useful at night providing enough indoor light to locate switches for room lamps or porch lights etc.

The duration of the LED lights ON/OFF cycle can be adjusted by changing the value of C2.

This electronic doorbell light circuit is entirely safe as it is effectively isolated from the potentially hazardous AC mains supply by IC1.

However, it is crucial to avoid accidental contact with the circuits front end which is directly connected to the AC supply.

It is advisable to house this doorbell light unit in a sturdy and convenient ABS enclosure for safety reasons.

Formula:

In reaction to a trigger signal, a monostable multivibrator also referred to as a one shot pulse generator produces a single output pulse.

An LED may be set to illuminate for a certain amount of time in an automatic doorbell light circuit by pressing the doorbell.

Formula for Pulse Width T:

In monostable mode, the values of the resistor R and capacitor C define the pulse width T of the output pulse produced by the IC 555.

T = 1.1 × R × C

where:

• T is the pulse width in seconds (s).
• R is the resistance in ohms Ω.
• C is the capacitance in farads F.

His method and formula offer a fundamental structure for creating an automatic doorbell light circuit with a monostable circuit utilizing an IC 555.

Modify component values according to desired functionality and particular requirements.

How to Build:

To build a Simple Automatic Doorbell Light Circuit follow the below mentioned assembling steps:

Prepare the components:

• Gather all the components listed in diagram.

Design the circuit:

• Connect the doorbell switch in parallel with the existing AC230V doorbell.
• Connect the opto coupler IC1 to the doorbell switch and the AC mains supply.
• Connect the 555 IC IC2 and the high brightness white LED D1 to the output of the opto coupler.

Assemble the circuit:

• Place the components on a PCB and solder them together following the circuit diagram.

Test the circuit:

• Insert the 6V battery into the battery holder and test the circuit by pressing the doorbell switch.
• The LED should light up for a short duration.

Adjust the LED duration:

• If needed, adjust the ON/OFF duration of the LED light by changing the value of capacitor C2.

Enclose the circuit:

• Place the completed circuit in a suitable ABS enclosure to protect it from accidental contact and environmental factors.

Install the circuit:

• Install the doorbell light unit near your doorbell, ensuring it is safely connected and mounted.

Note:

• Please note that working with electrical circuits involves risks.
• If you are not familiar with electronics, consider seeking assistance from someone experienced or consulting a professional.

Conclusion:

An Automatic Doorbell Light Circuit is a practical and convenient addition to any doorbell system, offering improved visibility and usability, especially in low light conditions.

By automatically illuminating the doorbell area when the doorbell is pressed, this circuit enhances convenience and helps occupants locate the doorbell switch more easily.

With its simple design and effective functionality, an automatic doorbell light circuit is a useful enhancement to any home or buildings entryway.

References:

Doorbell

Datasheet IC 4N35 optocoupler