Repeat timing circuit formed by PUT

Published:2011/8/25 7:42:00 Author:Nancy | Keyword: PUT, repeat timing circuit | From:SeekIC

Figure 1 is the repeat timing circuit formed by PUT. It is a repeat timing circuit composed by one PUT, two transistors and a diode, which is not effected by the change of the the power supply voltage and the temperature and has long-term stability. When PUT conducts, the anode current is shunted by the transistor VT2, the base current of VT1 is cut off and the PUT resets. The negative temperature coefficient of VD1 makes a temperature compensation to the offset voltage of PUT. The RP1 resistance is larger, which is 3 MΩ, so we should choose the gold/film resistor with small temperature effect and C1 selects a knob capacitor with small leakage current.



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