Self-adaptive constant current load circuit and power supply circuit

The utility model relates to a self-adaptive constant current load circuit and a power supply circuit, which can provide a self-adaptive constant current load when a capacitor needs to be discharged, and the self-adaptive constant current load circuit comprises a first constant current circuit, a voltage sampling circuit and at least one second constant current circuit, the first constant current circuit comprises a constant current control unit and a resistor R3; the voltage sampling circuit is used for detecting the voltage of the capacitor and controlling the on and off of the second constant-current circuit so as to control the resistance value of the constant-current load setting resistor; therefore, the constant current value of the capacitor during high-voltage discharge is small, the constant current value of the capacitor during low-voltage discharge is large, and the switching tube Q1 is always in the optimal working interval. According to the utility model, when the output voltage is switched, the