Project idea
Vary the DC motor’s speed by changing the PWM duty cycle so the average voltage across the motor changes, which directly alters motor speed.
An 8051 reads two buttons for speed up/down and generates timer‑based PWM to a motor driver that handles the motor current safely.
 
Project description
An AT89S52 board creates software PWM using timers and sends the signal to an L293D driver, with two tactile switches mapped to increment/decrement the duty cycle for smooth speed control.
The L293D provides a dual H‑bridge up to 600 mA/channel at 4.5–36 V, allowing a 12 V DC motor to be driven reliably under PWM control.
 
Total list of components
8051 development board (AT89S52)
L293D motor driver module
12 V DC geared motor (160–180 RPM), 
12 V 1 A DC adapter SMPS, 1 pc
12×12 mm tactile push buttons, 2 pcs 
40‑piece jumper wire bundle, 1 set 
Note: The L293D module includes screw terminals for easy motor hookup, reducing extra connectors needed.
Breadboard and PCB
 
Features
Button‑based speed up/down using 8051 GPIO with debounced tactile switches for discrete duty‑cycle steps.
Timer‑interrupt PWM on 8051 for smooth, software‑defined duty‑cycle control without dedicated PWM hardware.
Dual H‑bridge driver supports up to 600 mA/channel and motor supply up to 36 V for robust 12 V DC motor drive.
 
Applications
Student labs and training kits for learning PWM and motor control fundamentals on 8051.
Small robotics and conveyance mechanisms needing reliable variable‑speed DC drive.
Fan/pump prototypes and process demos requiring duty‑cycle based speed regulation.
 
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.
 
Shipping dimensions (cm)
Typical compact kit boxing: about 20 × 15 × 10 cm to accommodate the dev board, driver module, motor, adapter, and cabling safely.
 
Weight
Approximate net assembly: ~0.30–0.40 kg considering a small 12 V DC motor, 8051 board, driver module, adapter, and wiring in a desktop setup.
 
Estimate project weight: 1 kg
 
Notes: All the products are made by LearnElectronics India and not for re-sale.