Timer Circuits
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The circuit in Figure 1 is a simple, low-cost voltage-to-time converter using the ubiquitous 555 timer chip. You can use the IC`s monostable multivibrator as a voltage-to-time converter by connecting the analog-voltage input to the charging resistor, R,.... -
This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can.... -
The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and.... -
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These circuits provide a means of altering the YELLOW output of RED / GREEN type two colour light emitting diodes. These circuits use the LM555 timer chip... -
This page shows three circuits for using the 555 timer IC as a photocell controlled train detector. The circuit is shown driving light emitting diodes but any load of less than 200 milliamps could be used. Shown on the schematic is a secondary.... -
This circuit when used with a 555 timer will cause light emitting diodes to turn on and off more slowly. This will make the LEDs appear similar to incandescent lamps... -
The circuit uses independent timers to flash two light emitting diodes. Any time that light emitting diode D1 is lit__light emitting diode D2 will be switched off. Light emitting diode D3 is on if both D1 and D2 are off. Two versions of the circuit are.... -
The following are LM555 timer circuits that have unusual functions. Designed to time a sports event; In this circuit the GREEN output is adjusted to be on for 3 minutes and then the RED output is set for 1 minute in a repeating cycle. Each time the light.... -
This article describes a 2-Input alarm developed on the PIC LICK-1 Module using a Microchip PIC16F628-04. The program uses the internal 4MHz oscillator and if any other frequency is used, the timer values will need to be changed. A two zone alarm means the.... -
The circuit is based on IC1, which is a 555 timer IC in astable mode. It will power a 6 inch 4 Watt fluorescent tube off a 12 volt supply, consuming 300 mA. It may also be powered by a suitably rated universal AC/DC adapter. Advantages of the design are:.... -
This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn`t generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values.... -
This circuit will remove the transient spikes and contact bounces from a non-latching push button switch. Using a 555 timer as a monostable circuit, it is easy to build a good switch debouncer circuit. There are many circuits for SPDT debouncing, but not.... -
Using a single 555 Timer IC and a small transformer to generate a high voltage, this circuit will test zener diodes of voltage ratings up to 50VDC. The 555 timer is used in the astable mode, the output at pin3 drives a small audio transformer such as the.... -
A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps. Simple to build, simple to make, nothing too complicated here. However you must use the CMOS type 555 timer designated the 7555, a normal 555 timer will not work here due to the.... -
A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes. This timer circuit is similar to the 5 to 30 minute timer except that when switch S1 is closed, the on/off action of the circuit will continue.... -
When the 555 ic goes into timing mode (triggered by an output signal from the sound detector amplifier,) the timer`s output (pin 3) is set into HIGH for a duration set by C2, and R2. adjusting R1 will adjust how long it listens, from 10 seconds all the way.... -
Turns-off your amplifier when idle for 15 minutes Fed by amplifier tape-output. This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. Pushing P1 the device is switched-on.... -
This timer was designed for people wanting to get tanned but at the same time wishing to avoid an excessive exposure to sunlight. A Rotary Switch sets the timer according to six classified Photo-types ... -
The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep... 30.... -
A simple count-down LED timer that counts in minutes and seconds. Three buttons below the LED provide control of the unit, allowing you set the desired countdown time in minutes and seconds and a start/stop button. Completion of the countdown is indicated.... -
Pulse Generator kit will generate a frequency in KHz which can form a good test gear project. This kit is based on the classic LM555 timer IC. Input - 12 VDC Max @ 40 mA. Range - jumper selectable and preset tunable range of 1 Hz to 180 KHz. Power-On LED.... -
The resulting timer circuit is made from a CD4060, includes an oscillator and a 14 stage binary counter, two CD4040's, which are 12 stage binary counters, a CD4012 Dual Nand gate and a CD4013 Dual D Latch. The CD4060 is connected to a 32768 Hz ECS 3X8.... -
The 555 is configured in the standard astable oscillator circuit designed to give a square wave cycle at a period of around 1 cycle/sec. A potentiometer is included in the design so the period can be set to exactly 1 second by timing the LED flashesc. A.... -
This is a lamp timer capable of operating two separate relay switches. Outputs can be in three (or restricted to two) states: OFF, delayed ON and constant ON. Delayed ON mode is indicated by the LEDs. The source code is easily customizable for your needs:.... -
This is a simple one-valve irrigation controller made for our greenhouse. The code contains a software real-time clock (RTC) and a multiplexed 8-digit LED display and keyboard you can use in other projects. The operating software is simple, it contains a.... -
The timer is proposed an effective model for controlling an external load 8A/380V. Equipped with a 68HC11 mu.P associated with an 8 MHz crystal, it can get very precise programmable durations. Two lines are planned: from 0 to 99 seconds and from 0 to 99.... -
The choice of material to read or drive is the definition of three digits (Bit), RA0, 1,2 PORTA of the PIC at the entrance of 74HC138A. To select a material for reading or driving an output of 78HC138 is '0 '(Low), forcing the transistor (2SA1015) to conduct.... -
There are 4 timers in PIC18 which are timer0 to timer3. Timers are used when precise timing event need to be generated. Timers are usually used in conjunction with interrupt to keep the timing accurate. This guide will show an example of using timer0 to.... -
A 100 second delayed turn ON relay RL1 switch, if plug power +12V in circuit. In Fig.2 see a two range 6-60 second and 1-10 minute auto turn off relay timer circuit, with 555... -
A small circuit that can find a lot applications of measurement time. She has the possibility us inform with sound signal from the BZ1. At the same time, exist the possibility drive a external circuit via the optocoupler IC2, after we connect the applicable.... -
A wide rage auto turn OFF timer covering 1 minute to 20 hours in three ranges with S1. As soon as power is applied to the circuit the IC1 [555] starts to oscillate happily and feeds clock pulses to the IC2 [4017]. The IC2 [4017] and IC3 [4020] give a....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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