• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

Circuits for Beginners | Basic Circuits | LED Driver | Hobby Circuits | Transistor Circuits

New-Projects | Privacy Policy | About us | Contact | Disclaimer | Copyright | Videos

You are here: Home / Timer and Delay Relay / Switching Two Alternate Loads ON/OFF with IC 555

Switching Two Alternate Loads ON/OFF with IC 555

Last Updated on July 6, 2019 by Swagatam 29 Comments

ask questions through comments

In this post we learn how to make a simple IC 555 based alternate relay timer circuit for toggling a couple of loads alternately with a specified length of delay, as determined by the calculated values of the relevant components. The idea was requested by Mr. Sanjoy.

Circuit Objectives and Requirements

  1. I am a regular reader of your excellent posts. Here I would like to request a circuit design.
  2. I am trying to build a laboratory paper coating set up for which I am going to employ 2000 watts hair driers for drying of the coated paper.
  3. The problem is that those driers can't be run continuously.
  4. Therefore I decided to use two driers alternately for three minutes each. But alternate switching of these driers manually always is tiresome.
  5. So I request a circuit which will be able to switch on and switch off the the driers alternately and automatically for a preset period of time and continue doing this until switched off.

The Design

Referring to the below shown alternate switching relay circuit, or we can also call it an alternate switching flasher circuit, the idea may be understood with the help of the attached explanation.

The circuit is built around a standard IC 555 astable configuration, which basically produces an alternating high and low or an alternating 12V and zero volt at its pin#3 when switched ON.

This alternately switching output accompanies certain delay between its ON/OFF switching as determined by the component values of R1, R2, and C.

In the proposed design the values of these timing components are suitably calculated to produce an approximately 50% duty cycle, and having a delay length of around 180 seconds or 3 minutes.

With the shown arrangement, only the value of the 470uF capacitor needs to be altered for achieving other preferred time delays across the output pin#3.

The pin#3 can be seen connected with a transistor relay driver stage which responds to the high/low pulses from the pinout and accordingly switches the relay contacts across the N/C and N/O contacts.

Since the two loads are connected across these two contacts of the relay, these are also alternately switched from ON to OFF and vice versa with a delay of 3 minutes between each switching.

The two LEDs connected across the supply pins and the pin#3 of the IC helps to indicate which load may be in the switched ON or OFF position at a given instant.

The above explained alternate switching relay timer circuit can be also implemented for other identical applications and the ON/OFF periods can be independently adjusted for achieving different ON/OFF sequences, by suitably altering the R1/R2 timing components of the astable.

get free help for circuit diagrams

You'll also like:

  • 1.  Bird in the Nest Indicator Circuit
  • 2.  Quadcopter Remote Control Circuit without MCU
  • 3.  Input Trigger Synchronized Monostable Timer Using IC 555
  • 4.  Motorcycle Button Start Locking Circuit
  • 5.  Mains AC Xenon Tube Flasher Circuit
  • 6.  Class D Amplifier Circuit Using IC 555

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Subscribe for the Latest Posts


 

Reader Interactions

Comments

    Have Questions? Please post your comments below for quick replies! Comments should be related to the above artcile Cancel reply

    Your email address will not be published. Required fields are marked *

  1. Perera says

    November 2, 2021 at 10:07 pm

    What should i change for more timing delay ( 15minutes on and 5minutes off in loop)

    Reply
    • Swagatam says

      November 3, 2021 at 10:26 am

      You will have to experiment by using different resistor values for R1 and R2

      Reply
  2. B. Nagaraj says

    May 26, 2021 at 7:16 pm

    I need a timer which will help me in circulating water on and off for a desired time.
    Need your clarifications for the following points.
    1. Can I use just one motor (Load) to be operated instead of two in the circuit.
    2. If I need to adjust the on and off timing, will it be possible to go for preset replacing fixed resistor.
    3. What relay should I opt for if I use a 12 v motor, or 230 V motor.

    Reply
    • Swagatam says

      May 26, 2021 at 7:28 pm

      Here are the answers:
      1) Yes you can connect a single motor either to the N/C or the N/O contacts depending on whether you want the motor to be switched ON when power to the circuit is switched ON, or start with the motor OFF when power is switched ON.
      2) Yes that’s possible. You cab replace the R1 with a 1M pot or preset, but make sure to connect a 10K fixed resistor in series with this preset or pot.
      3) Relay will depend on the motor current specs, if it is less than 5 amps then you can use the ordinary cube shaped relay having a coil resistance of around 300 to 400 ohms.

      Reply
  3. Dr Basavaraja N S says

    April 1, 2021 at 12:10 pm

    A very informative and useable project. What if more than two devices are to be included in the project? Can this be modified to include variable number of devices working for variable time and at variable intervals?

    Reply
    • Swagatam says

      April 1, 2021 at 1:14 pm

      Thank you, only two loads can be used in this circuit, for variable time and variable number of loads, you will need to have many IC 555 arranged in a sequential form with variable time adjust

      Reply
  4. Bo Andersen says

    February 13, 2021 at 1:02 pm

    Hello
    This is just what i need, i have build it and it works ok with a lite load, like a LED on load A+B, but when i put a pump on (about 0.7 amp), the timing goes fubar, and unequal and drops from 3min to about 1min.
    Do you have a idea as to what goes wrong? hope i make sense. Thanks alot for your time.
    Bo Andersen

    Reply
    • Swagatam says

      February 13, 2021 at 8:29 pm

      Hi, Glad you could build it successfully.
      The problem could be due to the strong motor transients the IC 555 timing might be getting disturbed.
      Please do the following modifications to your IC 555 supply line.
      Power the IC 555 positive line through a 50 ohm or 100 ohm series resistor.
      Add a 1N4148 diode directly across the pin#8/4 and pin#1 of the IC. Cathode will go the pin#8/4.
      Also add a 100uF capacitor parallel with the above diode. Positive of the capacitor will connect with the cathode of the diode.
      Additionally increase the value of the pin#5 capacitor to 1uF or higher.
      Please do the above and see if that helps to solve the issue?

      Reply
  5. George Dechambeau says

    April 11, 2020 at 9:07 pm

    Would like to toggle between low/hi tone auto horns. Perhaps less than 1/2 second for each on cycle. Would need to eliminate horn output when momentary switch released. Output would control 12vdc relays. Circuit power 12vdc. Is this possible using above design?
    Formula calls for Ra to be 0, Rb to be 600 ohms and cap to be 3 micro farads. Seems both relays would be off if momentary switch were released.

    Reply
    • Swagatam says

      April 12, 2020 at 11:33 am

      Yes the above circuit will work, you can put the push switch in series with the 12V supply

      Reply
  6. Adeyemi says

    March 18, 2020 at 5:06 pm

    Good day sir, the circuit seems not to have 3secs delay in between on/off, please any way out. Also, please help
    Me out for r1, r2 and c for 10 secs on/off with 3secs delay inbetween, I have tried astable calculator but didn’t get it.

    Reply
    • Swagatam says

      March 19, 2020 at 9:03 am

      Adeyemi, use R1 = 1k, R2 = 100k, C = 47uF/25V

      Reply
  7. Kelvin Ng says

    December 5, 2019 at 8:34 am

    Hi Sir,.
    I have a question on Switching Two Alternate Loads ON/OFF with IC 555.
    Currently I had sequential arrow led installed on a Toyota side mirror.
    This sequential arrow led had 3 wire( neutral, pattern 1 , pattern 2 )
    Currently it is connected as pattern 1( wire connection is neutral , pattern 1 ) and I wish to use 2 pattern but couldn’t figure out how to do it. Alternating switching relay may work for me but unable to hide inside side mirror housing due to its size .

    When indicator is turn on, I wish to light up pattern 1 and than off (off for 0.6sec ), next pattern 2 and than off ( off for 0.6sec), next pattern 1… the cycle repeat until indicator is turn off.
    Battery voltage for this circuit is 12VDC and the power source to the circuit will be control by flasher relay( on and off interval is 0.6sec).

    Could you help?
    Thanks

    Reply
    • Swagatam says

      December 5, 2019 at 11:50 am

      Hi Kelvin, you can use an astable circuit such as this

      https://www.homemade-circuits.com/how-to-make-any-light-strobe-light/

      add the two sets of LEDs across the two collectors of the transistors

      Reply
      • Kelvin says

        December 7, 2019 at 11:27 am

        Dear Sir,

        Thank you for your replied but that isn’t the Circuit I’m looking for.
        I found a link in youtube which could be explain better.

        Could you help to covert that white bulky alternating relay into a circuit?
        Thanks
        Regards
        Kelvin

        Reply
        • Swagatam says

          December 7, 2019 at 12:17 pm

          Kelvin, the video shows a relay flip-flop alternately switching to every single input pulse. You can get the results by employing one of the circuits that explained in the following article

          https://www.homemade-circuits.com/build-these-simple-flip-flop-circuits/

          Reply
  8. gary vanarsdale says

    January 24, 2019 at 2:49 am

    I am looking for an alternating relay that will simply replace a manual 24 volt 3 position toggle switch; load A, off, load B, which operates two irrigation solenoid valves. When my mechanical timer shuts off, there is “no” power to the system, when the mechanical timer comes back on power is restored and i need to switch to the other valve, and so on. All the relays i have found require continous power to work. Can you tell me if i am looking for something no one makes???? I appreciate any input.
    Gary

    Reply
    • Swag says

      January 24, 2019 at 8:58 am

      It may be possible to switch loadA and loadB alternately, but how’s the off position supposed to be switched, i can’t figure it out? Please clarify this!

      Reply
  9. Jindro says

    January 18, 2019 at 4:18 am

    Hello Sir Good Morning! can i adjust it for 3 seconds each? Tnx Sir

    Reply
    • Swag says

      January 18, 2019 at 12:18 pm

      Hi Jindro, yes that’s possible, you can use the following software to adjust the concerned resistors and capacitor for getting the results:

      https://www.homemade-circuits.com/ic-555-timer-astable-circuit-calculator

      Reply
  10. adewale says

    June 17, 2018 at 12:29 pm

    Hi sir I really appreciate your concern I love so much for that you rely my message God will bless you and your family, pls I will he in touch if I need some support over circuit thanks.

    Reply
    • Swag says

      June 17, 2018 at 5:17 pm

      You are welcome Adewale, keep up the good work

      Reply
      • adebanji adewale says

        June 19, 2018 at 7:01 pm

        Thanks sir for your support, but I will let you know if I will need your technical support, from Adewale.

        Reply
        • Swag says

          June 19, 2018 at 8:44 pm

          You are most welcome!

          Reply
  11. adewale says

    June 10, 2018 at 4:35 pm

    hi swagatam I need a circuit that operate timer on interval of 45 mins on/off switch, pls kindly help.

    Reply
    • Swag says

      June 10, 2018 at 5:07 pm

      Hi Adewale, you can try the following circuit

      https://www.homemade-circuits.com/how-to-make-simple-versatile-timer/

      remove the feedback link, and set the pot to get 45 minute time intervals.
      pin#3 can be configured with a relay driver stage

      Reply
  12. John Boardman says

    February 16, 2018 at 11:27 pm

    I need a circuit that will time the duration of an induction heater. The heater run time can be from 1 to 30 seconds, depending upon part size and configuration, at which time it turns off, shutting off the power relay to the heater. It would then trip a second relay with operates a solenoid to remove the part from the heater and reset everything to the initial state. A push button would initiate the heating/part ejection cycle.

    Reply
    • Swag says

      February 17, 2018 at 2:03 pm

      what will be the operating voltage rating for the solenoid?

      Reply
  13. peeyush love says

    October 3, 2016 at 11:22 am

    which software is good for sumulation???

    Reply

Primary Sidebar



Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (52)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (98)
  • 741 IC Circuits (19)
  • Amplifiers (59)
  • Arduino Engineering Projects (83)
  • Audio Projects (94)
  • Battery Chargers (83)
  • Car and Motorcycle (94)
  • Datasheets (46)
  • Decorative Lighting (Diwali, Christmas) (32)
  • DIY LED Projects (89)
  • Electronic Components (97)
  • Electronic Devices and Circuit Theory (35)
  • Electronics Tutorial (109)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Fun Projects (12)
  • GSM Projects (9)
  • Health Related (19)
  • Heater Controllers (28)
  • Home Electrical Circuits (100)
  • How to Articles (20)
  • Incubator Related (6)
  • Industrial Electronics (28)
  • Infrared (IR) (40)
  • Inverter Circuits (98)
  • Laser Projects (12)
  • LM317/LM338 (21)
  • LM3915 IC (25)
  • Meters and Testers (64)
  • Mini Projects (156)
  • Motor Controller (66)
  • MPPT (7)
  • Oscillator Circuits (24)
  • PIR (Passive Infrared) (8)
  • Power Electronics (33)
  • Power Supply Circuits (74)
  • Radio Circuits (9)
  • Remote Control (47)
  • Security and Alarm (61)
  • Sensors and Detectors (118)
  • SG3525 IC (5)
  • Simple Circuits (74)
  • SMPS (29)
  • Solar Controllers (60)
  • Timer and Delay Relay (53)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (40)
  • Ultrasonic Projects (14)
  • Water Level Controller (45)


Circuit Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator


You can also Chat with me here:

Facebook
Twitter
YouTube
Instagram
My Facebook-Page
Quora



© 2022 · Swagatam Innovations

We use cookies on our website to give you the best experience.
Cookie settingsAccept All
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Please visit the Privacy Policy Page for more info.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Non-necessary
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
SAVE & ACCEPT