How to make circuits with bistables

In the last article we showed you how to make an electronic circuit using combinational logic, i.e. with elements whose output only depends on their input. Today we will teach you some basics of synchronous sequential logic. which is the basis of all memory and processors today.

The synchronous sequential logic is based on incorporating a clock signal into the elements. Thus the output of the circuit will depend, in addition to its input, on time. The basic component of sequential logic is the bistable.

Bistable D

As you can see in the image, there is an input D through which impulses enter and two outputs Q and Q' that return the response. In addition we can see the Clk (Clock) strand that makes the bistable to be activated only when there is a suitable impulse (edge or voltage).

Regarding the type of bistable, there are a large number of bistables that perform different functions, however, the most commonly used are the bistable D and RS.

Bistable Dsends to its output the same value as its input. It is usually used to store data. We can see its symbology in the image above.

RS BistableIf a 1 is sent at input S (Set), a 1 appears at its output. If a 1 is sent at input R (Reset), a 0 appears at its output.

RS Bistable

Having said that, we can start analysing some circuits made with bistables. Normally, sequential logic is used for memories, counters, calculations, repetition of actions over time, etc.

Some examples are as follows:


Serial overflow register (each clock pulse sends the state of one bistable to the next)


Counter made with bistable T (if T=1 the value of the output changes, if T=0 it remains constant)

As always, remember that you can ask any questions through our forum.

1 thought on “Cómo realizar circuitos con biestables”

  1. ...for the electronic circuits that we want to make, I would like a basic interpretation of the circuit and the confirmation that it has been tested...for example I am a novice and a failure of the diagram or the calculations, I will end up failing...Thank you!

Leave a Comment

Your email address will not be published.

Scroll to Top