Quiz - This project can be used for a quiz with up to 4 contestants (or teams). Each contestant has a trigger push-switch and LED. When a trigger switch is pressed it lights the corresponding LED, sounds the bleeper and prevents the other trigger switches from working - therefore showing which contestant was the first to press their switch __ Designed by John Hewes
Radio Clock for PC's - The heart of the device is a EM2S receiver module and matching antenna. The two are matched, so a mixing a 60kHz receiver board suitable for the MSF and WWVB signals with a 77.5kHz antenna and vice versa will not work. it should be noted that the receiver boards know nothing about the format of time signal itself so a 60kHz pair suitable for receiving the MSF signal will also receive the WWVB signal __ Designed by Jonathan A. Buzzard
Railway clock WiFi ESP8266-Lua - Swiss railway clock is precise digital wifI clock. it's a miniature web server and very good demo for ESP8266 & Lua fanclub.
By mapping ports of your router, you can connect to it from anywhere on the world. This clock uses Lua software and
trendy vector graphics format SVG with animations. The clock is particularly interesting for its graphic design. in terms of program, it using
synchronization the time from an external NTP server. Thanks to this, clock is quite fast and precision, which was my goal. __ Designed by © Pavel Janko
Rainbow Clock - Here is a simple circuit using different colour LEDs that makes your clock glow in different colours of rainbow. The clock’s dial (shown in Fig.2) is lit by colour LEDs...__ Electronics Projects for You
Random' Flasher for 8 LEDs - This project uses a 4026 counter and display driver IC to flash eight LEDs in an apparently random manner. it can be used to create a display of your choice. __ Designed by John Hewes
Ratiometric Sensor to Pulse Width, Non-Inverting Response - The LTC6992 is a silicon oscillator with an easy-to-use analog voltage-controlled pulse width modulation (PWM) capability. The LTC6992 is part of the TimerBlox family of versatile silicon timing devices. A single resistor, RSET, programs the LTC6992’s internal master oscillator frequency. The output frequency is determined__ Linear Technology/Analog Devices App Note, Jun 16th 2010
RC Servo Tester with 555 IC - Servo refers to an error sensing feedback control which is used to correct the performance of a system. Servo motor is a DC motor equipped with a servo mechanism for precise control of angular position. Servo motors usually have a rotation limit from 90° to 180°. Servos are used for precision positioning in robotic __ Designed by T.K. Hareendran
RC-Timed Shutoff Function Uses Op Amp & Momentary Switch - 02/16/12 EDN Design Ideas: Battery-operated instrument benefited from auto-power shutdown. A handheld, battery-operated “fiber finder” measures the light escaping from an optical fiber when clamped in a V-shaped block under slight pressure. A pair of photodiodes on each side of the resulting bend compares analog levels to indicate the presence and direction of light travel, and PLL tone decoders indicate the presence of as many as three optical-modulation tones. The idea is to “tag” a fiber with a central-office signal __ Circuit Design by Glen Chenier, Teeter Totter Tree Stuff, Allen, TX
Reaction Time Game - A clever design to test your knowledge about counters, state machines, displays, and how to put them together. Not only this project is very suitable for the schools, it is also very fun! ! ! This reaction time meter measures your reaction time, and can be built on a breadboard. __ Designed by Projects & Ideas from Nutchip.com
Reaction Timer - The circuit below can be used to test a person’s reaction time to a precision of ±0·01 seconds. The time is indicated by a series of seven LEDs showing the output of a binary counter (4060). The two D type flip-flops are in a 4013. The LED shown on the circuit diagram is the "stimulus". Switch S1 starts the timer and illuminates the stimulus led. Switch S2 stops the timer __ Designed by © David Hoult
Reaction Timer Game - This is a game for two players. Player 1 presses the START button. This resets the 4026 counter chip and starts the 555 oscillator. The 555 produces 10 pulses per second and these are counted by the 4026 chip and displayed on the 7-Segment display. __ 555-Timer
Realtime Clock with LCD Based On an Atmel AT89C4051 - if you are looking for the simplest project, you are at the right place. its a digial clock which make use of AT89C4051 to work as a Real time clock. __ Designed by Ajay Bhargav ajay_bhargav @ hotmail.com
Real-time-clock chip makes low-power oscillator - 11/23/00 EDN Design Ideas: Many systems use watch-crystalbased, 32.768-kHz oscillators. in battery-powered designs, the 32-kHz oscillator may consume a fairly high percentage of the total power budget. Reduced power consumption. PDF has many circuits, scoll to find this one __ Circuit Design by Yongping Xia, Teldata Inc, Los Angeles, CA
Regularly Repeating Interval Timer - Timer Circuits: This circuit has an adjustable output timer that will re-trigger at regular intervals. The output period can be anything from a fraction of a second to half-an-hour or more - and it can be made to recur at regular intervals of anything from seconds to days and beyond. __ Designed by Ron J.
Relay clock - Even if relay logic is now an old technology, I haven’t abandoned it. This clock circuit works for a sequence of 4 relays only, but the schematic is repetitive, so it may be extended. The relays K and K1 work in astable condition and are supposed to send the clock signal to the others. Once the circuit is supplied the cycle has to be triggered by pressing the button, then it continues without stopping __ Designed by Andrea-Central Italy
Relay Delay - This circuit waits for a set time and then activates a relay. With the cap that is in the schematic you will get about a 6 sec delay till power on. You can change the cap in this circuit to 470uF for about a 20 sec delay__
Relay Toggle Circuit Using a 555 Timer - This 555 timer circuit below toggles a relay when a button is pressed. Pins 2 and 6, the threshold and trigger inputs, are held at 1/2 the supply voltage by the two 10K resistors. When the output is high, the capacitor charges through the 100K resistor, and discharges when the output is low. When the button is pressed, the capacitor voltage is applied to pins 2 and 6 which causes the output to change to the opposite state __ Designed by Bill Bowden
Relay Toggle Circuit Using a 556 Timer - This toggle circuit operates by using a couple 555 timers wired as inverters. Pins 2 and 6 are the threshold and trigger inputs to the first timer and pin 5 is the output. The output at pin 5 will always be the inverse of the input at pins 2 and 6. Likewise, the output at pin 9 of the second timer will always be the inverse of the input at pins 8 and 12. A 100K resistor connects the output of one inverter to the input of the other so the state of one will be the opposite of the other. __ Designed by Bill Bowden
Relay Toggle using a 555 Timer - This is probably the best toggle circuit. __ Designed by Bill Bowden
Relay: Delayed Turn-on - This circuit is a delayed turn-on relay driver and can produce time delays for up to several minutes with reasonable accuracy. The 14001 (or 4001) CMOS
gate here is configured as a simple digital inverter. its output is fed to the base of a regular 2N3906 (PNP) transistor, Q1, at the junction. __ Designed by Tony van Roon VA3AVR
Relay-12 Sec to 90 min - Schematic and notes only, no circuit description provided. __ Designed by Tony van Roon VA3AVR
Reliable 555 Timer Doesn’t Falsely Trigger - 01/06/11 EDN Design Ideas: Powering the timer from a NOR gate keeps it unpowered until needed. [Design ideas by John Dawson, Opelika, AL __ Circuit Design by John Dawson, Opelika, AL
Remote Controlled Lighting - This remote controlled switch circuit can control AC loads such as lights, fans etc through the remote handset of TV. it uses the 555 timer in the bistable mode. in the bistable mode output IC 555 keeps two states, either low or high. When a negative pulse is applied to the trigger pin 2 of 555, the output turns high and __ Designed by D Mohankumar
Renewable Energy Powered Timer Relay Switch - Powering an AA battery powered timer thermostat directly with a 12V power source. __ Designed by REUK-Renewable Energy UK website
Repeat Timer - Make a repeat timer circuit with large intervals between ON times. __ Designed by REUK-Renewable Energy UK website
Repeating Interval Timer No.2 - This circuit is based on a simple asymmetric oscillator. The length of time the relay remains energized - and the length of time it remains de-energized - are set independently. With the component values shown in the diagram - both periods are adjustable from about 1 to 30 minutes __ Designed by Ron J.
Repeating Interval Timer No.2 - Timer Circuits: This is a simpler repeating timer circuit. it uses just one CMOS
IC - wired as an asymmetric oscillator. The length of time the relay remains energized - and the length of time it remains de-energized - are set independently. __ Designed by Ron J.
Repeating Timer No.3 - Timer Circuits: This circuit is very similar to Repeating interval Timer No.2 . However - the addition of a light dependent resistor means that the operation of this timer can be limited to the daylight hours. A variable resistor (preset) lets you choose the level of darkness at which the timer will cease to function. __ Designed by Ron J.
Repeating Timer No.4 - Timer Circuits: This circuit is the opposite of Repeating Timer No.3 . its operation can be limited to the hours of darkness. Again - the variable resistor (preset) lets you choose the level of darkness at which the timer will begin to function. __ Designed by Ron J.
Repeating Timer No.5 - Timer Circuits: This circuit is a temperature controlled version of Repeating Timer No.3 . The light dependent resistor has been replaced by a temperature dependent resistor or thermistor. And a small preset potentiometer lets you choose the temperature above which the timer will operate. __ Designed by Ron J.
Repeating Timer No.6 - Timer Circuits: This circuit is the opposite of Repeating Timer No.5. it will only begin to operate if the temperature falls below the preset level. Again - the variable resistor (preset) lets you choose the temperature below which the timer will function. __ Designed by Ron J.
Repeating Timer No.7 - Timer Circuits: This timer is based on a simple CMOS
4001 Monostable Circuit. The length of the ON period - and the length of the OFF period - can be set independently. With the right value timing components - periods of up to an hour or more are available. __ Designed by Ron J.
Repeating Timer No.8 - Timer Circuits: This circuit has an adjustable output time of up to one-hour. And it can be set to repeat at intervals of up to 24-hours and beyond. it's a single IC version of my first - CMOS
4060 based - Repeating Timer. __ Designed by Ron J.
Repeating Timer No.9 - Timer Circuits: This circuit has two independently adjustable 24-hour timers. There's a relay-timer that will energize the relay for up to 24-hours. And there's a repeat-timer that will restart the relay-timer - at regular intervals of up to 24-hours. it's a more versatile version of my first Repeating Timer. __ Designed by Ron J.
Replacing 556 with two 555's - Here is a handy reference to replace a 556 dual timer with two 555's__ 555-Timer
Reverse Bias Oscillator - There are a number of npn transistors that will oscillate in the audio range when reverse biased. Minimum supply voltage is 7V for low power transistors such as BC109, BC238 and 2N2222A, it becomes 12V for medium power transistors such as BD139 and is 16V for power transistors as BUX22 and 2N6543. Current drain is 4mA at 9V and frequency of oscillation is 550Hz. The base is normally left open. __ Contact G. Forrest Cook
Robust 10MHz reference clock input protection & distributor for RF systems - 07/31/14 LTC Design Notes: Design a protected 10MHz reference input without degrading phase noise. __ Circuit Design by LTC Design Note
Room Sentry - counts the number of people entering a room, for use with a pir module __ Contact P. Townshend - EduTek Ltd
Rotation Counter - Presented here is a simple rotation counter which helps you measure the revolutions per minute (rpm) of any rotating object. As the project requires measurement of very high rpm, a fast-switching...__ Electronics Projects for You
Roulette - This circuit creates a rotating LED that starts very fast when a finger touches the TOUCH WiRES. When the finger is removed, the rotation slows down and finally stops. __ 555-Timer
Routing: the Next Big Problem in Physical Design - 05/28/01 EDN Design Ideas: San JoseRight about the time the country was counting and recounting votes in the presidential race, another counting and recounting was taking place: the number of tape-outs using new physical-synthesis tools. The attention paid to this event is understa __ Circuit Design by Joe G. Xi
RPM Counter using Microcontroller AT89c4051 - Counting the revolutions per minute (RPM) of motors—determining the motor speed— is essential in the field of industrial automation. it is useful especially for closed-loop control systems where proper action can...__ Electronics Projects for You
Rules of Thumb Aid in Timeconstant Analysis - 11/07/97 EDN Design Ideas: An RC circuit charges or discharges to within 36.8% of the total excursion in one time constant, t, where t=RC. However, 36.8% is an awkward figure, and you usually need a calculator to achieve reasonable accuracy. You need a sho __ Circuit Design by Tony Zizzo, Burr-Brown, Tucson, AZ