| 摘要 |
<p>PURPOSE:To make it possible to measure resistance values varying over a wide range, as in spark plugs, by a simple structure, by a method wherein a current dividing circuit is provided in parallel with a resistance used for indication inserted between the object whose resistance value is to be measured and a constant voltage source, and a current dividing circuit is provided in parallel with the resistance of this current dividing circuit. CONSTITUTION:Current dividing circuit L1 connected in parallel with zener diode D1 and resistance R1 is connected in parallel with resistance 3 used for indicator 4 inserted between the object whose resistance value is to be measured 1 and constant voltage source 2. In parallel with resistance R1 is also connected current dividing circuit L2 connected in parallel with zener diode D2 and resistance R2. Now, let the value of resistance of object 1 be represented by rx, the resistance value of protective resistor RO by r0, the voltage applied on the voltmeter by Vx, and the voltage across D1-D3 by Vz. Then the values of resistances 3, R1, R2 and R3 are determined so that Vx becomes respectively Vz, 2Vz, 3Vz and 4Vz when rx is respectively 10<2>r0, 10r0 and 10<-1>r0. By this, when rx=10<2>r0, we have Vx 10<2>Vz, and even if the resistance value of object 1 is changed by the order of 10<4>, it is possible to measure the resistance value. The range of measurement can be expanded by increasing the number of stages of current dividing circuits.</p> |
