Repeating timing circuit composed of PUT lamp

(1) Introduction to circuit principle As shown in 3-38, it is a repetitive timing circuit composed of PUT, etc. It is a repetitive timing circuit
composed of 1 PUT, 2 transistors and 1 diode
, and is not affected by power supply voltage changes and The effect of temperature changes and long-term stability. When PUT is turned on, transistor VT2 shunts its anode current and cuts off the base current of VT1 to turn it off. PUT reset. The negative temperature coefficient of VD1 temperature compensates the offset voltage of the PUT . RP1 has a larger resistance value of 3Mrz. Therefore, a metal film resistor with small temperature effect should be selected , while Ct should use a button capacitor with small leakage current. R． The resistance value should be lower than 3. 3kfl. If the resistance value is too large, the leakage current of PUT will make the operation of VT2 unstable. A lkfZ resistor should be used in the circuit. Island and R3 suppress the discharge current of c] , thus protecting the transistor and PUT.