Simple transistor relay delay pull-in circuit diagram

The figure below is a relay delay pull-in circuit composed of transistors. When the power is first turned on, the voltage on the 16μF capacitor is zero, both transistors are cut off, and the relay does not operate. As the 16μF capacitor is charged, after a period of time, the voltage on it reaches a high level, both transistors are turned on, and the relay is delayed and closed. The delay time can reach 60s. The delay time can be adjusted through the 10MΩ resistor.