Industrial X-ray flaw detector delay control switch circuit diagram

This example introduces the delay control switch of an industrial X-ray flaw detector, which can start the exposure system with a delay of 30 seconds. In this way, workers can use this 30 seconds to quickly leave the X-ray flaw detection machine to reduce the absorbed dose of X-rays and prevent X-rays from damaging their health.

How the circuit works

The delay control switch circuit of the industrial X-ray flaw detector consists of a voltage stabilizing filter circuit, a delay control circuit A, a delay control circuit B and a control execution circuit, as shown in the figure.

The voltage stabilizing filter circuit is composed of capacitors C5, C6 and a three-terminal voltage stabilizing integrated circuit IC3.

Delay control circuit A consists of resistors R1 ~ R3, capacitors C1, C2, time base integrated circuit IC1, diode VD1, relay K1, light-emitting diode VL1 and control button Sla.

Delay control circuit B is composed of resistors R4 ~ R6, capacitors C3, C4, time base integrated circuit IC2, diode VD2, relay K2, light-emitting diode VL2 and control button Slb.

The control execution circuit is composed of the normally closed contacts of relays K3 and K1, the normally open contacts of K2, and the high-voltage button S2.

IC1 and IC2 form two monostable triggers with external resistor-capacitor components respectively. Normally (when S1 is not pressed), pin 3 of IC1 and IC2 both output low level. When S1 is pressed, Sla and Slb are connected, causing pin 2 of IC1 and IC2 to become low level. The monostable trigger flips and enters the transient state. Pin 3 outputs high level, and relays K1 and K2 are both energized and closed. , VL1 and VL1 are both lit, the normally closed contact of K1 is disconnected, and the normally open contact of K2 is connected; at the same time, C1 and C3 are charged through R2 and R5 respectively. When the voltage at both ends of C1 charges to 8V (about 30 seconds), the circuit in IC1 flips over and returns to a steady state from the transient state. Pin 3 becomes low level, VLI goes out, K1 is released, and its normally closed contact is connected, and K3 When powered on, the normally open contact of K3 is connected (equivalent to pressing the high voltage button S2), and the exposure circuit is powered on. After another 8s delay, IC2 also flips to a stable state, and its pin 3 becomes low level, causing VL2 to go out, K2 and K3 to release, and one exposure ends.

Component selection

R1~R6 use 1/4W metal film resistors or carbon film resistors.

C1, C3 and C5 all use aluminum electrolytic capacitors with a withstand voltage of 16V; C2 and C4 use monolithic capacitors or polyester capacitors.

Both VD1 and VD2 use 1N4007 silicon rectifier diodes.

Both VL1 and VL2 use Φ5mm light-emitting diodes.

Both IC1 and IC2 use the NE555 time base integrated circuit.

K1~K3 use 4098 or JZC-23F, JRX-13F type 12Y DC relays.

S1 uses a small push button: 52 still uses the high-voltage switch on the original flaw detector panel.