JS20 single junction transistor time relay circuit diagram

Crystal oscillator

Circuit principle: The circuit consists of five parts: delay link, amplitude detector, output circuit, power supply and indicator light. The voltage regulation part of the power supply consists of a resistor R and a voltage regulator vs. to supply power to the delay link, the thyristor VTH and the relay in the output circuit. KA is powered directly by a half-wave rectifier circuit. After the power is turned on, it is rectified by the diode VD1, filtered by the capacitor cl, and regulated by RJ and VS, and then the capacitor G is charged through RP1 and R4. The voltage on the capacitor G gradually increases exponentially. When the voltage is greater than the peak voltage of the single junction transistor VT, the single junction transistor is turned on, G passes through the eb1 pole of the VT and the wind discharges, and the pulse voltage is output on the wind to trigger the gate. When the VTH is turned on, the relay KA is pulled in, and the contact of the KA is short-circuited at the same time to make it discharge rapidly. The voltage between the ebl of the single-junction transistor drops rapidly, and when it drops to the valley voltage of Vr., Vr is turned off. At the same time the LED indicator lights up. When the power is turned off, the relay KA is released, the circuit returns to the original state, and waits for the next action. The delay time can be adjusted by adjusting RP.