Project idea
Build a relay-driven star–delta starter demonstrator that powers six lamps arranged to mimic a three‑phase motor, starting in star for reduced voltage and switching to delta at full voltage using a 555 monostable timer delay. The setup illustrates reduced starting current and torque in star and normal operation in delta, matching standard industrial practice for squirrel‑cage induction motors.
 
Project description
At power‑on, a 555 timer in monostable mode energizes a relay set for the star configuration for a preset time; after timeout, the relays reconfigure to delta to apply full line voltage to the lamp phases, showing dim‑to‑bright transition that correlates with VL/3VL/3 to VLVL behavior. The relay logic follows typical star–delta changeover with interlocks to ensure only one configuration is active at a time, aligning with standard starter schematics and timing concepts used in industry and PLC implementations.
 
Project components
555 timer IC (NE555), DIP‑8, 1 pc.
8‑pin IC socket, low cost, 1 pc.
12‑0‑12 V, 1 A step‑down transformer, 1 pc (for relay/logic DC supply).
12 V DC SPDT sugar‑cube relays, 10 A, 3 pcs (main, star, delta).
General‑purpose PCB ~14 × 9 cm or equivalent area, 1 pc.
B22 bulb holders, 6 pcs (lamps emulate three‑phase load).
Assorted resistors set for timing and bias networks, 1 kit (covers 1/4 W values).
Cables and connectors for mains and low‑voltage wiring (quantity per layout).
Fuse and holder for mains input protection, 1 set (ratings per supply).
LEDs for status indication, diodes for flyback (e.g., 1N series), small‑signal transistors for driving coils, electrolytic and ceramic capacitors for timing/decoupling (covered by small‑parts assortment).
 
Features
Soft start via star connection reduces starting current roughly to one‑third compared to direct delta, minimizing mechanical and electrical stress.
Automatic star‑to‑delta transition using a 555 monostable ensures consistent, adjustable delay timing with simple, robust hardware.
Safe visual demonstration using lamps to emulate a three‑phase motor allows clear observation of dim (star) to bright (delta) behavior without coupling to an actual high‑power machine.
 
Applications
Educational trainer for motor starting methods and contactor/relay logic used in industrial control systems and PLC labs.
Pre‑deployment concept validation of star–delta sequencing and interlocks before commissioning on actual induction motors.
Demonstrations of inrush mitigation, torque control at start, and line stress reduction techniques in power and drives courses.
 
Project Includes:
Fully assembled and tested circuit
Circuit diagram
Source code 
(For DIY KITs - only the components will be provided)
 
Project Types:
DIY KIT(Do IT YourSelf KIT) - We are providing only components in this kit for this project
DIY KIT with Code & Circuit Connections - Along with the components, you will get the Code and the Circuit Connections file to help you build the project easily.
Readymade Breadboard - We are providing fully assembled, tested and ready-made project using plug-n-play jumper wires and breadboard with all the other components, code & circuit diagram.
Readymade Soldered - We are providing fully assembled, tested and ready-made project soldered on a PCB with all the other components, code & circuit diagram.
 
Dimensions (cm)
Suggested electronics board footprint ~14 × 9 × 3 cm based on a commonly available general‑purpose PCB of 14 × 9 cm and low‑profile components mounted on top.
Lamp panel (holders in two rows of three) ~20 × 10 × 5 cm depending on enclosure and spacing for safe creepage/clearance and wiring access.
 
Shipping dimensions (cm)
45 x 35 x 18 cm(L X W X H)
 
Weight
The relay weight is about 11 g per unit, and three units contribute ~33 g, while the transformer dominates mass for a 12 V 1 A unit and the PCB and holders add modest weight.
Assembled electronics (board with transformer and relays) commonly falls in a few‑hundred‑gram range due to the iron‑core transformer; lamp holders add additional grams when included.
 
Estimated project weight: 6kg
 
Notes: All the products are made by LearnElectronics India and not for re-sale.