Time relay

As a time delay control component, time relay is widely used in industrial control and other aspects. Since most of the time relays do not come with a circuit diagram, this is inconvenient for maintenance. This example introduces a JST-l type time relay circuit using CD4069 non-gate digital integrated circuit for reference during use and maintenance.
Circuit Operation Principle The time relay circuit consists of a +l2V power supply circuit, an oscillating circuit, a delay trigger circuit, and an electronic switching circuit, as shown in Figure 8-135.

The +l2V power supply circuit is composed of a resistor Rl-R3, an intermediate relay KA coil, a diode VDl, a Zener diode VS, and a filter capacitor Cl.
The oscillating circuit is composed of a non-gate D5, D6 and a capacitor C2, a resistor R4-R6, a potentiometer RP1, and a diode VD2 inside the non-gate integrated circuit IC (Dl-D6).
The delay trigger circuit is composed of internal non-gates D1, D2, D4, resistor Rg, potentiometer RP2, RP3, capacitor C3 and diode VD3.
The electronic switch circuit is composed of an intermediate relay KA, a thyristor VT, resistors R7, R8, and a capacitor C4.
AC 220V (or AC 380V) voltage through the R1 and KA coil current limiting step-down, VDl rectification, R2 second step-down, VS voltage regulation and Cl filtering, provide l2V DC working voltage for the IC. At this time, the current flowing through the KA coil is small, which is insufficient for K to be sucked.
After the oscillating circuit is energized, the oscillating operation is performed, and the generated oscillating signal is inverted and buffered by the non-gate D4, and then the C3 is charged through R9, VD3, RP2, and RP3. When the voltage across C3 is charged to a certain value, the non-gates D1 and D2 are inverted in reverse, and the voltage of about l2V is output from the 4th pin of the IC. After the voltage is divided by R7 and R8, the VT is triggered to conduct, and the KA is energized and combined with self-locking. Repeat the above process when the power is turned off after the power is turned off.
Adjust the resistance of RPl to change the frequency of the oscillator.
Adjusting the resistance of RP2 and RP3 can change the length of the delay.
Component selection
Both Rl and R2 use 1/2W metal film resistors; R3-R9 selects 1/4W metal film resistors.
RPl-RP3 uses small organic solid potentiometers.
Both Cl and C3 use aluminum electrolytic capacitors with a withstand voltage of 16V; C2 uses monolithic capacitors or polyester capacitors.
VDl selects 1N4007 type silicon rectifier diode; VD2 and VD3 select 1N4148 type silicon switch diode.
VS selects 1/2W, l2V silicon Zener diode.
VT selects the thyristor of lA, 600V.
IC selects CD4069 or CCl4069, MCl4069 type six non-gate integrated circuits.
KA selects the relay with the coil voltage of 220V AC (or AC 380V) and the contact current capacity of lOA.