30s timing circuit composed of PUT lamp

(1) Introduction to the circuit principle shown in Figure 3-37
is a 30s timing circuit composed of PUT, etc. This
circuit inputs a setting pulse and after a certain time (30s)
, outputs a pulse with a specified pulse width. The amplitude of the output pulse can be close to the supply voltage, and circuits
with low supply voltage can also work. If a set pulse is added between
the cathode and anode of PUT1 , PUT1 will be turned on. The
+5v
power supply charges the capacitor (j) through this, and the upper voltage of C. is
the anode voltage of PUT2, which gradually increases. When the anode voltage
is higher than the bias voltage of the gate, PUT2 is turned on. (The discharge current
of j passes through this Drive the transistor VT1 to make it saturated and conduct, and the output U(, is close to ov. At this time, the voltage on Cz reversely biases PUT1. PUT1 is cut off to reset the circuit. The output pulse width is basically determined by C2 and ruler. Connect the element in the figure Device parameters . The pulse width is about 10 lis. The delay time of the output pulse is set by Rz, r, pin and (?i). The setting of R2 and resistance value should ensure that the anode current of PUT1 is as large as the drying point current, so as to maintain Its conduction state. In order to reduce the peak current of PUT2 , to increase the gate resistance, a resistor can be connected to the gate.     (2) Component parameter selection The selection of components is shown in Figure 3-37. No special requirements. (3) The 30s timing circuit     composed of PUT, etc. is shown in Figure 3-37.