Touch Activated Light
The circuits below light a 20 watt lamp when the contacts are touched and the skin resistance is about 2 Megs or less. The circuit on the left uses a power MOSFET which turns on when the voltage between the source and gate is around 6 volts.
8 Channel software controlled fanbus with PWM
This article is about a software controlled, parallel port-interfacing 8-channel Pulse-Width-Modulated fan controller.
Stepper motor controller
This project allows you to control the speed, direc-tion, and step size of a unipolar four-phase step-per motor. The controller is capable of handling motor winding currents of up to 1.25 amps per phase and it operates from a single supply voltage of 6-30 volts DC.
The Relay Sub Board
The board is now designed so that it may be cut in two to make two separate boards, each with four relays. This should be more than adequate for most purposes.
This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer.
Plants Watering Watcher
This circuit is intended to signal when a plant is needing water. A LED illuminates at maximum brightness when the ground in the flower-pot is too dry: it dims gradually as the water's content in the pot grows, turning off when the optimum moisture's level is reached.
Photo Timer Circuit
Time is set by potentiometer R2 which provides a range or 1 sec. To 100 seconds with timing capacitor C1 of 100uF. The output at pin 3 is normally low and the relay is held off.
This timer was deliberately designed for people wanting to get tanned but at the same time wishing to avoid an excessive exposure to sunlight.
This circuit was developed since a number of visitors of this website requested a timer capable of emitting a beep after one, two, three minutes and so on, for jogging purposes.
Mini Metronome circuit diagram
This circuit is intended for alerting purposes after a certain time is elapsed. It is suitable for table games requiring a fixed time to answer a question, or to move a piece etc. In this view it's a modern substitute for the old sandglass.
Bedside Lamp Timer
The purpose of this circuit is that of power a lamp or other apparatus for a given time (30 minutes in this case), and then to turn it off.
Precision Metronome and Pitch generator
CMos IC1 and IC2B quad AND gate form a 2.4576 MHz crystal oscillator plus a 2400 times divider.
4 channel infrared remote relays
4 Channel Infrared (IR) Remote is a simple kit using the famous HT12A and HT12D encoder / decoder chips from Holtek
Dual Relay Driver Board
Dual Channel Relay Board is a simple and convenient way to interface 2 relays for switching application in your project.
Solid state relay switch
Solid State Relay Switch is a simple kit which will help you control (ON / OFF) a single high power circuit from a low power drive.
IR Remote Volume Controller
IR Remote Volume Controller circuit diagram
Simple optical switch
The 555 is proved to be the most versatile and ubiquitous IC all over the world.This is a possible use: simple inverting schmitt trigger.
Time Delay Relay II
When activated by pressing a button, this time delay relay will activate a load after a specified amount of time. This time is adjustable to whatever you want simply by changing the value of a resistor and/or capacitor.
Time Delay Relay
A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts specified. The current capacity of the circuit is only limited by what kind of relay you decide to use.
Automatic Fan Controller
Automatic Fan Controller
Dark Sensitive Switch
Dark Sensitive Switch is a simple project which operates a relay when the light falling on the LDR goes below a set point.
DC servo motor driver
DC Servo Motor Driver kit, designed using MC33030 IC, is the fastest and low cost way of getting your DC Servo Motor up and running.
High current bipolar stepper motor controller
High Current Bipolar Stepper Motor Controller kit is based on chopper drive. Chopper drive is a method of providing a constant current source to a device. Chopper drive allows for use of higher voltage power supply for better performance and higher speed. It is uses SGS Thomson's L297 and L298 controller IC's.
Auto Heat Limiter for Soldering Iron
Usually a soldering iron takes a couple of minutes to get adequately heated up to melt the solder, after which the heat generated is much above the requirement and is wasted. Moreover, excessive heat decreases the life of the bit and the element, causing serious damage to the components.
Simple DC motor PWM speed control
When the potentiomenter is all up, the Rcharge resistance is 1,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 21 Kohm, giving a 5% on duty cycle and a 1Khz frequency.
Stepper Motor Controller
The circuit is very simple and inexpensive. This is good thing because most commercial stepper motor controller ICs are quite expensive. This circuit is built from standard components and can easily be adapted to be controlled by a computer.
Pulse Width Modulation DC Motor Control
Often, people attempt to control DC motors with a variable resistor or variable resistor connected to a transistor. While the latter approach works well, it generates heat and hence wastes power. This simple pulse width modulation DC motor control eliminates these problems.
Infa-Red Remote Control
This remote transmits a tone using an infa-red LED. This tone is decoded by the receiver. Since the receiver only switches when it hears the tone, there are no accidental activations.
This circuit adopt a rather old design technique as its purpose is to vary the speed of a fan related to temperature with a minimum parts counting and avoiding the use of special-purpose ICs, often difficult to obtain.
Dark-activated LED or Lamp Flasher
Dark-activated LED or Lamp Flasher
DC Motor Reversing Circuit
Reverse rotation of DC electric motor.
On-Off Temperature Control
On-Off Temperature Control device circuit diagram. It's useful for turning on and off devices by high or low temperature.
DC Motor Control Circuit
Circuit for managing DC motor.
Temperature based fan control. Very useful if you want to have quiet cooling while the device is not at full power.
Unipolar Stepper Motor Controller
circuit diagram for controller for stepper motor.
PWM Motor-Light Controller
Pulse width modulation controller for regulating motor speed
AC Current Monitor
This circuit was designed on request, to remotely monitor when a couple of electric heaters have been left on.
Multi Rocket Launcher
Simple circuit for rocket model starter.
On-Off Temperature Control
This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint.
DC Motor Reversing
A DC motor reversing circuit using non latching push button switches. Relays control forward, stop and reverse action, and the motor cannot be switched from forward to reverse unless the stop switch is pressed first.
Single Zone CMOS Alarm
This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It has provision for normally open and normally closed switches and will accommodate the usual input devices such as Foil Tape, Pressure Mats, Magnetic Reed Contacts, Passive Infrared Detectors and Inertia (Shock) Sensors.
5 Zone Alarm System
This is a complete alarm system with 5 independent zones suitable for a small office or home environment.
A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes.
A simple thermistor triggered cold switch with adjustable threshold.
Secure any electronic device using this electronic keypad. Circuit is relatively simple and it's built with 4081 CMOS quad 2 input "AND" gate
Garage - Shed Alarm
This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays. It's designed to be used with the usual types of normally-closed input devices such as - magnetic-reed contacts - micro switches - foil tape - and PIRs.
5 to 30 Minute Timer
A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps.
Car Alarm and Immobilizer
This circuit features exit and entry delays, an instant alarm zone, an intermittent siren output and automatic reset. By adding external relays you can immobilize the vehicle and flash the lights
This circuit takes the guesswork out of proximity detection by inducing eddy currents in a living being, whether animal or human. May serve as alarm or some kind of switch.
Infra Red Switch
This is a single channel (on / off) universal switch that may be used with any Infra Red remote control using 36-38kHz
Hot Water Level Indicator
A simple device to indicate various levels of hot water in a tank.
Dark Activated Switch
This circuit will activate a relay when light falls to a preset level. Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer.
Voltage Controlled Switch using 555 Timer
Voltage Controlled Switch with popular 555 timer circuit used in a novel way.