Research on Applications of Monostable Trigger 74121

The input characteristics of trigger input-terminals and the pin 11 of integrated monostable multivibrator 74121 were discussed in this paper.The effective factors for temporary stability time of 74121 were analyzed deeply.Four self-exciting multivibrator circuits constituted with single 74121 are proposed.And the operation principles of these circuits are presented.The calculating formulas for frequency of oscillation are studied and the comparative analysis with practical test results is performed.The theoretical analysis and the experimental results verify that the value range of timing components in 74121 monostable circuits can be extended properly and the single 74121 self-exciting multivibrator is feasible.