| 摘要 |
PROBLEM TO BE SOLVED: To connect circuits excepting an LED display circuit control means to a drive voltage supply means, to reduce the manufacturing cost and to reduce the price providing a transistor between the drive voltage supply means and the control means. SOLUTION: A noise sensitive circuit, e.g. a voltage controlled oscillation circuit 122 is connected to a drive voltage supply part 131 through a voltage regulator 103 for the voltage controlled oscillation circuit. Then, even when noise occurs in the output voltage of the drive voltage supply part 131 at an LED 116-118 turn-on time, since the noise is removed by the voltage regulator 103, the failure doesn't occur in the voltage controlled oscillation circuit 122. Further, by providing an NPN transistor 130, the output voltage of a DC-DC converter 102 is taken out as the output voltage of the drive voltage supply part 131. Thus, other circuits are connected to the poststage of the drive voltage supply part 131.
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