Operational amplifier multivibrator
- a simple multivibrator oscillator circuit using a
single op amp
Multivibrator oscillators are used in many circuits and they
are simple to construct. It is possible to construct them using a couple of
transistors, but it is also possible to construct a very simple multivibrator
oscillator circuit using an operational amplifier. The circuit can be used in a
variety of applications where a simple square wave oscillator circuit is
required.
The use of an operational amplifier integrated circuit is
ideal from many viewpoints. Although circuits can be made using just two
transistors, operational amplifiers are also very cheap these days, and there is
often little to choose in terms of cost.
The operational amplifier multivibrator circuit comprises two
sections. The feedback to the capacitor is provided by the resistor R1, whereas
hysterisis is provided by the two resistors R2 and R3.
Operational amplifier multivibrator oscillator
The time period for the oscillation is provided by the
formula:
T = 2 C R1 loge (1 + 2 R2 / R3)
Although many multivibrator circuits may be provided
using simple logic gates, this circuit has the advantage that it can be used to
provide an oscillator that will generate a much higher output than that which
could come from a logic circuit running from a 5 volt supply. In addition to
this the multivibrator oscillator circuit is very simple, requiring just one
operational amplifier ( op amp ), three resistors, and a single capacitor.
|
