Alarms, control, timers electronic circuits
Timers, alarms, detectors and other sensor based circuit diagrams
4 Channel Infrared (IR) Remote is a simple kit using the famous HT12A and HT12D encoder / decoder chips from Holtek... [read]
In this circuit, the alarm will be switched on under the following four different conditions: 1. When light falls on LDR1 (at the entry to the premises). 2.... [read]
A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps.... [read]
This is a complete alarm system with 5 independent zones suitable for a small office or home environment.... [read]
It is very interesting and convenient to be able to control everything while sitting at your PC terminal.... [read]
This article is about a software controlled, parallel port-interfacing 8-channel Pulse-Width-Modulated fan controller.... [read]
This circuit was designed on request, to remotely monitor when a couple of electric heaters have been left on.... [read]
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... [read]
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.... [read]
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... [read]
An infra-red or wireless remote control has the disadvantage that the small, handy, remote transmitter is often misplaced. The sound operated switch has the... [read]
Here is a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with... [read]
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... [read]
Dark Sensitive Switch is a simple project which operates a relay when the light falling on the LDR goes below a set point.... [read]
The circuit presented here wakes you up with a loud alarm at the break of the daylight. Once again the 555 timer is used here. It is working as an astable... [read]
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... [read]
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.... [read]
Dew (condensed moisture) adversely affects the normal performance of sensitive electronic devices. A low-cost circuit described here can be used to switch... [read]
Dual Channel Relay Board is a simple and convenient way to interface 2 relays for switching application in your project.... [read]
Secure any electronic device using this electronic keypad. Circuit is relatively simple and it's built with 4081 CMOS quad 2 input "AND" gate... [read]
Temperature based fan control. Very useful if you want to have quiet cooling while the device is not at full power.... [read]
This circuit warns the user against fire accidents. It relies on the smoke that is produced in the event of a fire. When this smoke passes between a bulb and... [read]
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... [read]
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.... [read]
A simple device to indicate various levels of hot water in a tank.... [read]
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... [read]
This is a single channel (on / off) universal switch that may be used with any Infra Red remote control using 36-38kHz... [read]
This circuit can be used as an Infrared beam barrier as well as a proximity detector.... [read]
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,... [read]
This simple circuit using a single transistor turns ON the relay when light falls on the LDR. The potentiometer is adjusted for the required sensitivity.... [read]
This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint.... [read]
On-Off Temperature Control device circuit diagram. It's useful for turning on and off devices by high or low temperature.... [read]
Using dual flip-flop IC CD4027 employ a 555 based monostable circuit to supply input clock pulses. The circuit described here obviates this requirement.... [read]
A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes.... [read]
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... [read]
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... [read]
CMos IC1 and IC2B quad AND gate form a 2.4576 MHz crystal oscillator plus a 2400 times divider.... [read]
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... [read]
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... [read]
Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances. This remote control unit... [read]
This circuit gives out an alarm when its sensor is wetted by water. A 555 astable multivibrator is used here which gives a tone of about 1kHz upon detecting... [read]
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.... [read]
Here is a teleremote circuit which enables switching on and off of appliances through telephone lines. It can be used to switch appliances from any distance,... [read]
A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here.... [read]
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... [read]
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.... [read]
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... [read]
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.... [read]
Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorder,... [read]
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... [read]
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... [read]
This timer was deliberately designed for people wanting to get tanned but at the same time wishing to avoid an excessive exposure to sunlight.... [read]
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... [read]
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.... [read]
This circuit utilizing a 555 timer IC can be used as an alarm system to prevent the theft of your luggage, burglars breaking into your house etc. The alarms... [read]
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... [read]
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... [read]
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,... [read]
This is a simple but effective alarm circuit which can reset its self after a time that you select. it has normally open and normally closed triggers which... [read]
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... [read]
Circuit of a new type of remote control switch is described here. This circuit functions with inaudible (ultrasonic) sound. Sound of frequency up to 20 kHz... [read]
Voltage Controlled Switch with popular 555 timer circuit used in a novel way.... [read]
This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full. The circuit uses the widely... [read]
Alarms, control, timers
- Audio
- Tools and measuring
- Power supplies
- Light and LED
- Radio
- Telephone related
- Miscellaneous
- For your car
- PC related
Top 15 circuits