Project idea
Build an 8051‑driven single‑phase cycloconverter that outputs F, F/2, and F/3 by gating a pair of antiparallel SCR bridges; the microcontroller selects the division and generates phase‑synchronized gate pulses to the power stage.
Opto‑isolated triac‑driver devices such as MOC3021 are commonly used to interface low‑voltage controllers to mains‑side thyristor gates for motor speed and AC power control, aligning with the project’s isolation and trigger‑drive needs.
 
Project description
The controller detects mains zero crossings and schedules firing angles to alternately enable positive and negative bridge SCRs so the output fundamental is effectively reduced to F/2 or F/3 while preserving isolation and robust gate drive via optocouplers intended for motor and lamp dimming control tasks.
 
Hardware specifications:
8051 Microcontroller
Thyristor
Crystal Oscillator
Resistors
Capacitors
Transistors
Cables and Connectors
Diodes
PCB and Breadboards
LED
Transformer/Adapter
Push Buttons
Switch
IC
IC Sockets
Bulb
Software Specifications
Keil µVision IDE
MC Programming Language: C
 
Features
Three selectable speeds (F, F/2, F/3) via front‑panel switches with isolated gate drive to SCR bridges for safe AC interfacing.
Uses 12 A class SCRs suitable for single‑phase motor control and AC power switching with robust surge capability in TO‑220 packages.
Opto‑isolated triggering designed for 115/230 VAC operation to protect the 8051 logic domain while driving inductive loads.
 
Applications
Educational demonstration of cycloconverter‑based speed control for single‑phase induction motors in labs and workshops.
Variable AC power control use cases such as lamp dimming and fan/motor speed controllers with microcontroller selection and safety isolation.
 
📦 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)
Typical on breadboard: about 12 × 10 × 6 cm assembled around a 400‑point board footprint and ancillary power/gate modules (breadboard core is 8 × 5 × 1 cm).
PCB build can match a 10 × 10 cm layout if consolidated, with height depending on heat sinks and terminal blocks (estimate aligned to breadboard footprint).
 
Shipping dimensions (cm)
Packed unit with cushioning and bulb: approximately 20 × 14 × 10 cm to accommodate board, wiring, and protective padding based on compact board sizes cited.
Allowance ensures safe transport for through‑hole TO‑220 devices and fragile lamp while keeping package volume low for courier rates.
 
Weight
Assembled prototype weight ≈ 0.35–0.45 kg, anchored by board (≈40 g), multiple TO‑220 SCRs, passives, and wiring, with small components in gram‑scale ranges (e.g., 1N4007 ≈ 0.35 g/pc).
 
Shipping weight: with packing and bulb typically ≈ 1 kg depending on enclosure and heat‑sink choices for the TO‑220 SCRs
 
Notes: All the products are made by LearnElectronics India and not for re-sale.