Frequency Divider Circuit

Figure 1.  Frequency Divider Circuit Diagram

This is a frequency divider circuit, or a circuit whose output frequency is a fraction of the frequency of its input.  The main component of this circuit is the 555, a versatile timer IC.  In this circuit, it is configured as a monostable multivibrator, i.e., it will output a single pulse at pin 3 every time its pin 2 is 'triggered' by a pulse.

The width of the output pulse at pin 3 of the circuit above is defined by the product of R1 and C1, i.e., increasing the value of R1C1 will increase the output pulse width. Once the circuit above is triggered by a pulse at pin 2, the pin 3 output pulse cycle defined by R1C1 will first have to be completed before any subsequent pulses at pin 2 can trigger the circuit again. R1C1 of the circuit above can therefore be adjusted to define the number of input pulses equivalent to a single output pulse. Thus, this circuit is in effect dividing the input frequency by an integer.