Short duration pulses can be obtained with the relaxation oscillator that uses common transistors and is shown in the figure. The circuit basically consists of a regenerative switch with complementary transistors and its operating frequency depends both on the 4.7 M ohm resistor (which can be changed) and on the value of capacitor C. The maximum frequency that this circuit can generate is the order of 100 kHz. The supply voltage must be in the range indicated for the best functioning of the circuit. In many applications this circuit replaces oscillators with relaxation that make use of unijunction transistors.
