Simple Smoke Alarm using Photo Interrupter Module

This is a really simple smoke alarm circuit design. The circuit consists of two important modules that are sensor module using a photo interrupter module and alarm module using a tone generator IC NE555 with astable multivibrator configuration and then connected to the speaker, so you can hear the alarm sound.

Digital Fan Speed Control

This is the digital fan speed control circuit design that can be utilize to control the speed of 220V fans using induction motor. The speed control is nonlinear, i.e. in steps. The current step number is displayed on a 7-segment display. Speed can be varied over a wide range because the circuit can alter the… Read More »

250W RMS Power Amplifier Legend Stage Master

Here is the 250W RMS power amplifier circuit called Legend-Stage Master. This is the previous version of Legend-Stage Master MK2. The circuit is based on power MOSFET and give a great output performance for indoor audio sound system.

Unipolar Stepper Motor Driver

This is the circuit design of unipolar stepper motor driver to control unipolar stepper motors with 5, 6 or 8 wires. It uses four MOSFET IRFZ44. This circuit can be operated in free-standing or PC-controlled mode.

500W RMS Power Amplifier Based MOSFET

This is 500W RMS power amplifier circuit design, build based on MOSFET. The circuit is very popular in EE audio hobbyist as “LEGEND stage Master MK2”. It is a very good and powerful amplifier. It uses 12x power MOSFET IRFP240.

Simple Electronic Siren Based LM358

This is a low cost, simple, yet a surprisingly powerful electronic siren powered by just a 9V battery. The circuit may provide the final circuit block module in an alarm circuit using a relay to activate it.

Bipolar Stepper Motor Driver

This bipolar stepper motor driver circuit will drive a bipolar stepper motor using externally supplied 5V levels for stepping and direction. These usually come from software running in a computer or from a microcontroller unit. The circuit uses IRFZ44 and MTP2955 MOSFET’s.

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