Discharge type one-shot timing circuit composed of PUT lamp

(1) Introduction to circuit principle As shown in Figure 3-39, it is a discharge-type one-shot timing circuit composed of Fh PUT and others. When there is no input signal, PUT1
is turned off, and the transistor VT1 is also turned off. At this time, C.
Charge to the supply voltage U[x:. If an input signal is added,
PUT1 is turned on, VT1 is also turned on, and
current flows in the load RL. At this time, the potential at point a is
2 times the power supply voltage Ucc ffj, and C2 and G are each charged to the power
supply voltage U[r. From this point on, C1 starts to discharge through MA and
RP1, and the potential at point A slowly decreases. After reaching
the set time, if the potential of point b is lower than the potential of point c
, PUT2 will be turned on. After this discharge, the potential at
point d rises to close to the power supply voltage U{.i,, therefore
, the potential at point e is higher than the power supply voltage , then PUT1
is reverse biased and cut off, the transistor VTI is also cut off, and
there is no current in the load RL circulation, the circuit is reset.
(2) Component parameter selection The selection of components is shown in Figure 3-39, and there are no special requirements. (3) The discharge-type one- shot timing circuit
composed of PUT, etc. is shown in Figure 3-39.