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 feeding any appliance connected to SK1. Input audio signal is boosted and squared....

If you are familiar with LED flashers using transistor, you may know the basic one uses two transistor, one capacitor and three resistors. There is other kind of oscillator called "flip-flop". As I'm starting to develop some basic circuits, I need a simple....

When the phototransistor is stroken by IR light it conducts and the voltage between the 1Mohm resistor(arbitrary) and the phototrans drops from VCC to lower values. When the voltage drops lower than VCC/3 the 555 is triggered and goes high (from 0 TO VCC).....

The Clock Controller was designed to be an exemplary of using 'C' language to control timer0interrupt, 7-segment LED and keypad scanning. It provides 1-bit sink currentdriving output, for driving a relay, opto-triac, say. Many projects requiring7-segment....

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....

This schematic uses the 555 timer and the 4017 IC to drive 3 LED, to simulate the trafic lights...

The signal emitted by an IR remote control contains two parts, the control pulses and a modulated carrier wave. The control pulses are used to modulate the carrier, a popular modulation frequency being 36 and 42KHz. The signal is radiated by an IR diode,....

Typical circuit representative of those used in most light switch type digital timers. The timer module is normally a PIC or custom chip, and it syncs to the AC line so that a trigger pulse can be supplied at the right moment...

The instrument used to measure battery capacity. The battery may be charged to any current in the range 0-3 A. The load current may be constant, may change over time or even break off completely. Unloading stops when the battery voltage drops below the set....

This application note uses a timer IC (ICL7555), CMOS logic and discrete transistors to automatically control the conversion the MAX190 12-bit SAR analog-to-digital converter (ADC). The delay between conversions can be programed using a resistor. Logic....

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 tool is based on a NE555 (or LM555) timer i.c., wired as an astable multivibrator. The frequency of the multivibrator is determined by the value of the unknown capacitor Cx. The circuit can be fed by a small battery. I use myself a 9 V block battery....

This project describes how to build a "soft touch" switch. By "soft touch" we mean that you have to push once to set device ON and push again to set device OFF. This kind of switch works by latching a relay to ON state with push of a button and with another....

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 project takes advantage from -HOLD input, which is connected to push-button P1. As long as the -HOLD input is low, truth table's timeouts have no effect because this input serves to disable any state change provoked by timers. The effect is to freeze....

In this project it was used the ?Piranha Super-flux RGB? Led of common anode, and the PIC18F25K20, in order to generate combinations of colors. It has two function modes, automatic that generate the color sequence that is stored in the ?C memory, and the....

This novel buzzer circuit uses a relay in series with a small audio transformer and speaker. When the switch is pressed, the relay will operate via the transformer primary and closed relay contact. As soon as the relay operates the normally closed contact....

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...

In the article you will find a description of the universal PIC programmer, which suggested the involvement of Jens Madsen Dyekjar [ http://www.jdm.homepage.dk/newpic.htm ]. Program allows districts PIC12C5XX, 12C67X, 16C55X, 16C61, 16C62X, 16C71, 16C71X,....

The IC1 is a 555 timer IC is connected for, Astable operation the clock pulses are fed to the IC2 via the 10K resistor. The IC2 is a 10 stage counter, output 6 (pin 5) is connected to RESET (pin 15), thus giving us a 6 stage counter , outputs 0 to 5. The 6....

A simple two tone water alarm that is light enough to be worn on the upper arm of a sleeper is described. It uses two LMC555 CMOS timer chips followed by a complimentary pair of emitter followers to drive an 8 ohm speaker. Power is supplied by a 9 volt....

Li-Ion batteries are normally charged with a current limited constant voltage for a fixed length of time. At the end of this time period, the voltage must be removed to prevent internal chemistry changes in the battery. At a minimum, a timer is needed to....

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....

This circuit utilising 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 goes ON when a thin wire, usually as thin as a hair is broken. The circuit is straightforward. It....

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....

Most switch-mode power supplies rely on a PWM (pulse-width-modulated) output that is controlled via voltage feedback. A 555-timer IC can inexpensively perform PWM. The circuit in Figure 1 shows how to turn a 555 PWM circuit into an switch-mode power supply....

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....

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 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....

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....

A simple SWR meter first needs a calibration to Uv = 100 % (forward power). When switching over to Ur (reflected power) the SWR is indicated. This procedure has to be repeated every time a change is made to the transmit power, antenna tuner or frequency etc.....

This is the timekeeping test circuit. It includes a one-transistor circuit to switch in the 5V power supply when present and drop back to the 3v battery the rest of the time. That loop of blue wire-wrapping wire is a lariat used to quickly and easily pull....