| 摘要 |
PURPOSE:To obtain a trigger circuit which is variable in frequency over a wide range by composing a wave number varying circuit of a counter, arranging resistances of a frequency varying circuit at intervals of 1/2<n> (n = 1, 2...), and selecting them by a selector which can be connected in parallel. CONSTITUTION:A wave number setter 9 and a frequency setter 10 consist of pull-up resistances (RA1-RA4 and RB1-RB3) and switches (SA1-SA4 and SB1-SB3). The output signal of the wave number setter 9 is inputted to a wave number counter 11, whose set value input terminals (A1-D) are so constituted as to read and set an output level as a hexadecimal code. The frequency setter 10 performs similar operation. For example, the resistances R for frequency variation are set to a resistance value 1/2<n> based upon 153kOMEGA and various resistance values are obtained, so the frequency is varied over the wide range.
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