The automatic street-cum-porch light integrates the functionalities of street and porch lights into a single unit, optimising space and reducing clutter. By using LEDs, it offers energy savings and allows users to customise the lighting according to their needs. The use of LM358 and timer 555 ICs provides sophisticated control and automation features, ensuring a seamless user experience.
POC Video
Fig. 1 shows the author’s prototype.
Automatic Street-Cum-Porch Light – Circuit and Working
The circuit diagram of the street-cum-porch light is shown in Fig. 2. It is built around a 12V adaptor connected across JACK1, op-amp LM358 (IC1), timer NE555 (IC2), two BC548 transistors (T1, T2), 12V SPDT relay (RL1), and a few other components.
The NE555 timer is configured in monostable mode to generate a preset time output, thereafter, going low. One op-amp from the LM358 is used to compare voltages and the voltage developed by the LDR when light is falling on it. The NE555 timer IC2 is triggered by the output of IC1A and transistor T2 based on the light falling on the LDR. The output of the op-amp LM358 is connected to mode change switch S1. The output of the NE555 timer is also connected to mode change switch S1.
| Parts List | |
| Semiconductors: | |
| IC1 (IC1A-IC1C) | – LM358 operational amplifier |
| IC2 | – NE555 timer |
| T1, T2 | – BC548 npn transistor |
| D1 | – 1N4007 rectifier diode |
| LED1 | – 5mm LED |
| Resistors (all 1/4-watt, ±5% carbon), unless stated otherwise: | |
| R1, R2, R5, R6, | |
| R9, R10 | – 1-kilo-ohm |
| R3 | – 15-kilo-ohm |
| R4 | – 100-kilo-ohm |
| R7, R8 | – 10-kilo-ohm |
| R11 | – 270-kilo-ohm |
| VR1 | – 100-kilo-ohm potmeter |
| Capacitors: | |
| C1 | – 4.7µF, 35V electrolytic |
| C2 | – 0.2µF, ceramic disk |
| C3 | – 0.01µF, ceramic disk |
| C4 | – 1000µF, 35V electrolytic |
| Miscellaneous: | |
| LDR | – Small size |
| JACK1 | – DC socket |
| CON1, CON2 | – 2-pin connector |
| S1 | – SPDT switch |
| RL1 | – 12V, 1 changeover (1CO) relay |
| relay230V, 100-watt bulb | |
| relay12V adaptor for power supply | |
| 230V AC mains power supply | |
Timer IC2 with RC components decides the on time at output pin 3 to switch on the porch light via relay RL1. Here, in RC, the time-deciding components are resistors R10 and R11 as ‘R’ and capacitor C4 (1000µF) as ‘C.’ These time-deciding RC can be set to around five minutes to switch on the porch light.
The transistors and relay RL1 are used to switch the street and porch lights on and off based on the output of the LM358 as well as the output of the NE555. A common relay RL1 is used to drive both the street-light and the porch light.
Construction and Testing
An actual-size, single-side PCB layout of the street-cum-porch light circuit is shown in Fig. 3, and its component layout is shown in Fig. 4. After assembling the circuit on the PCB, enclose it in a suitable box. The street-cum-porch light circuit will then be ready for use. After powering on the circuit, keep the SPDT switch S1 towards either street-light or porch light based on the choice.
After assembling the components, install the unit near the porch, if it is to be used as a porch light. On the other hand, if it is to be used as a street light, install it near the street light.
Bonus: You can watch the complete step-by-step video tutorial below:
S.C. Dwivedi is an electronics enthusiast and circuit designer at EFY
