Improved single-shot timing circuit composed of 2 PUT lamps

(1) Introduction to circuit principle As shown in Figure 3-40, it is an improved one-shot timing circuit composed of 2 PUTs. If the set signal is added,
the circuit is set, the transistor VT1 becomes conductive, the relay K is energized, and at the same time supplies voltage to the delay voltage . As a result, the capacitor Cl is
charged through Ri, and PUT1 is turned on by the forward voltage
. At this time, Cl passes through PUT1. Ni and VD2
discharge. The forward voltage drop of VDZ conduction causes
the anode gate of PUT2 to be reverse biased and cut off, and the circuit is reset.
It should not be used to limit the discharge current of cl and make
the reverse bias time between the anode and gate of PUT1
long enough. Since the reverse bias signal for circuit reset is not applied between the anode and the gate of PUT2, the sudden voltage change
during commutation will not have any impact on the load circuit. According to the component parameters in the figure, the single-trigger time is about 5s. Adjust the resistance of Ri to change the timing time.     (2) Component parameter selection The selection of components is shown in Figure 3-40, and there are no special requirements. (3) An improved one- shot timing circuit composed of two PUTs is shown in Figure 3-40.