| 摘要 |
PURPOSE:To measure the resistance value of a blasting circuit accurately by an ordinary voltmeter, only by flowing a fine current to the blasting circuit while using an operational amplifier. CONSTITUTION:An R1 and an R1', and an R0 and an R0' are resistances having an equal resistance value in couples, an Rv is a variable resistance, and an Rx is a resistance to be measured. Between the free terminal of the R0' and a terminal T2, a pointer type voltmeter M is inserted to compose a closed circuit of the resistances and voltmeter M. The connection point between the resistances R1 and R2 is connected to the addition point 2 of an operational amplifier A, and that between the resistances R1' and R0' is connected to the reference point 3 of the operational amplifier A. The output point 6 of the amplifier A is connected between the voltmeter M and terminal T2. Then, if the voltage of the voltmeter M is l0 and the power voltage (l), l0=-(Rx/2R0)l, so that value of the resistances Rx is found. When the (l) is 3v, and R0 and R1 are about 1.5kOMEGA respectively, resistance values between about 1 and 100OMEGA are measured with <=1mA currents. |
