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Flip Flop using IC 4017 and IC 4093

A very simple yet effective electronic toggle flip flop switch relay circuit can be built around the IC 4017 and IC 4093, we will see how this can be implemented from the following explanation.

What's a Flip Flop Circuit

A flip flop relay circuit works on a bistable circuit concept  in which it has two stable stages either ON or OFF. In When used in practical applications circuits it allows a connected load to alternately toggle from an ON state to OFF state and vice versa in response to an external ON/OFF switching trigger.

In our following examples we will learn how to make a 4017 IC and 4093 IC based flip flop relay circuits which are designed to respond to alternate inputs triggers, and correspondingly operate a relay and a load alternately from an ON state to OFF state and vice versa.

By adding just a handful of other passive components the circuit can be made to toggle accurately through subsequent input triggers either manually or electronically.

A couple of very useful flip flop toggle switch circuits are explained here.
They may be operated through external triggers either manually or an electronic stage. Circuit schematics of these flip flop circuits have also been included.

Simple Electronic Toggle Switch Flip Flop Circuit Using IC 4017

A very simple and effective electronic flip flop toggle switch circuit can be built around the IC 4017. The component count here is minimum, and the result obtained is always up to the mark.

Referring to the figure we see that the IC is wired into its standard configuration, i.e. a logic high at its output shifts from one pin to the other in the influence of the applied clock at its pin # 14.

The alternate toggling at its clock input is recognized as clock pulses and is converted into the required toggling at its output pins. The whole operation may me understood with the following points:

Flip Flop Circuit Using IC 4017

Parts List

R4 = 10K,
R5 = 100K,
R6, R7 = 4K7,
C6, C7 = 10µF/25V,
C8 = 1000µF/25V,
C10 = 0.1, DISC,
IC = 4017,
T1 = BC 547, T2 = BC 557,
IC2 = 7812

How it Works

We know that in response to every logic high pulse at pin #14, the output pins of the IC 4017 are switched high sequentially from # 3 to # 11 in the order: 3, 4, 2, 7, 1, 5, 6, 9, 10, and 11.

However, this proceeding may be stopped at any instant and repeated by just connecting any of the above pins to the reset pin # 15.

For example (in the present case), pin # 4 of the IC is connected to pin #15, therefore, sequence will be restricted and will bounce back to its initial position (pin # 3) each time the sequence (logic High) reaches pin # 4 and the cycle repeats.

It simply means that now the sequence toggles from pin # 3 to pin # 2 in a back and forth manner constituting a typical flip flop action. The operation of this electronic toggle switch circuit may be further understood as follows:

Every time a positive trigger is applied to the base of T1, it conducts and pulls down pin # 14 of the IC to ground. This brings the IC to a standby position.

The moment the trigger is removed, T1 stops conducting, pin # 14 now instantly receives a positive pulse from R1. The IC acknowledges this as a clock signal and quickly toggles its output from its initial pin #3 to pin #2.

The next pulse produces the same result so that now the output shifts from pin #2 to pin #4, but since pin #4 is connected to reset pin #15, as explained, the situation bounces back to pin #3 (initial point).

Thus the procedure is repeated every time T1 receives a trigger either manually or through an external circuit.

Accurate CMOS Flip Flop Circuit Using IC 4093

CMOS Flip Flop Circuit Using IC 4093

Another simple and very accurate flip flop circuit can be made using three gates of IC 4093. Looking at the figure we see that the inputs of N1 and N2 are joined together to form logic inverters, just like NOT gates.

It means that, any logic level applied to their inputs will be inverted at their outputs. Also, these two gates are connected in series to form a latch configuration with the help of a feedback loop via R5.

N1 and N2 will instantly latch the moment it senses a positive trigger at its input. Another gate N3 has been introduced basically to break this latch alternately after every subsequent input pulse.

The functioning of the circuit may be further understood with following explanation:

How it Works

On receiving a pulse at the trigger input, N1 quickly responds, its output changes state forcing N2 to also change state.

This causes the output of N2 to go high providing a feedback (via R5) to N1’s input and both the gates latch in that position. At this position the output of N2 is locked at logic high, the preceding control circuit activates the relay and the connected load.

The high output also slowly charges C4, so that now one input of gate N3 becomes high. At this juncture, the other input of N3 is held at logic low by R7.

Now a pulse at the trigger point will make this input also go high momentarily, forcing its output to go low. This will pull the input of N1 to ground via D4, instantly breaking the latch.

This will make the output of N2 to go low, deactivating the transistor and the relay. The circuit is now back to its original state and ready for the next input trigger to repeat the entire procedure.

Parts List

R3 = 10K,
R4, R5 = 2M2,
R6, R7 = 39K,
R4, R5 = 0.22, DISC,
C6 = 100µF/25V,
D4, D5 = 1N4148,
T1 = BC 547,
IC = 4093,

Need Help? Please leave a comment, I'll get back soon with a reply!


  1. dear sir i am trying to make the above circuit but i am not able to understand that how i can trigger flip-flop manually to turn relay on/off. please help me out.

  2. Dear Ankit,

    Touch the positive supply with the "trigger" point momentarily, everytime you do this the relay will switch ON and OFF alternately.

  3. Dear sir,

    I made this circuit and its working but problem is every time i connect power supply relay gets on automatically and it doesn't show any activity if i sort triggering wire with positive of my power supply i checked several times connectivity and spare parts too. please help me once again...


  4. Dear Ankit,

    I have tested the above circuits thoroughly and they worked perfectly for me, so it would be difficult to understand your circuit problem.

    Alternatively you can try the first circuit given in the following link:

    Build only the IC1 section, remove T2 and all parts at the left of T2, don't remove R5, change the position of C3 and connect it across pin14 and ground. Now trigering pin14 with positive will produce the required results.

  5. What could be the relay in IC 4093 cct?? means it has the specific value or what? kindly guide me as soon as possible.

  6. the relay could be as required, depending upon the load and the supply voltage for the circuit

  7. Hi sir,
    i am Vishnu
    i am newer in electronics. last one month i am regularly reading your blogs related with my project.
    i require IR remote controlled circuit diagram for home appliances ( 4 lights and 1 Fan ) having memory back up for storing relay state during power failure. could you help me for developing the same. ?

  8. Hi Vishnu, you can try the following concept as explained in the article:

  9. Hi. To build 1st ciruit if i have 12v dc suply i think its not necessary to build ic2 section which is nothing but voltage regulation. Tell me if iam wrong. Thanks in advance

  10. yes it won't be necessary if the supply is fairly constant.

  11. Sir,
    I am a retired person ( 63 running ). I am residing at Howrah, W.B. (Pin code : 711102 ). I have been madly searching for fully solid state automatic voltage stabilizers for my 40' LED TV & LAPTOP ( DELL ). Because of voltage fluctuation, both of my ( previous )Sony make 46" LED, 3D TV as well as the LAPTOP became out of order. The Sony TV could not be repaired by the dealer( Power board not avail able ), but somehow the laptop got repaired. Would you please take the pain to intimate me the address, phone no., approx. cost of 2 nos. fully solid state automatic voltage stabilizers for my 40" LED TV ( Mitashi )& LAPTOP ( DELL ) ? Eagerly waiting for your response. Regards, S. DATTA, e-mail : ( ph. : 0 99030-88252 / 0 89610-44436 )

  12. Hello Mr. Datta,

    you can try the following concept for your need

    but please note that this circuit might require an advanced knowledge of electronics for successfully completing it.

  13. dear sir
    I am really happy to write you. I have one question about flip -flop Ic 4093.
    what is the group number of this ic?
    I mean El 4093 or MF 4093 ?
    only 4093 can't find in shop. plz help me. thank you.

  14. Shihab, you just have to say "IC 4093" to the shopkeeper, and you must get it....the initial prefix is not important. If the shopkeeper doesn't understand then he seriously lacks knowledge, in that case you can yourself check the available options from him and look for the number 4093 on the IC

  15. Helo SWAGATAM thank for ur great work ,i tried the first circuit with ic4017 above and trigered using an electronic circuit and the load switched on but when i trigered again to switch off the load it refused ,then i powered off the circuit then switched on again and trigered the load switched on but fail to go off for second triger,please help me how to solve this problem .thanks so much

  16. Thanks davis, it could be happening due to voltage spikes at pin#14, which might be forcing the output to randomly bounce to some irrelevant output pinout.

    you can try configuring the output of the 4017 through diodes, as shown in the first circuit of this article

  17. Yes SWAGATAM i made changes as u said like output for simple clap switch but now i power on circuit the relay activate and switch on the load before even i triger the circuit. Help me about this

  18. connect pin#15 with ground through a 100K resistor, and connect a 0.22uF or any capacitor below 1uF across pin#15 and the positive line.

  19. Wawoo its working fine now. Thanks so much SWAGATAM realy awesome , i love ur site so much . Now sir for there other circuit for obstacle avoiding robot can i use sm0038 infrared receiver in place of tsop1738? Thanks so much

  20. Glad to know it's working Davis, yes you can use SM0038, it's specs are similar to TSOP


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