| 摘要 |
PURPOSE:To achieve compensation for the ambient temperature by inserting a compensation circuit exceeding a positive temperature-resistance change in the winding of an ammeter into a measuring circuit after a detection element varying in the resistance value and the measuring circuit are connected to a constant voltage source circuit having a negative temperature voltage property. CONSTITUTION:A constant voltage source 1 is made up of a battery 2, a resistance 3 and a light emitting diode 4 and a negative characteristic thermistor 6 and the winding 8 of an ammeter 7 are connected in series to a measuring circuit 5. A negative characteristic thermistor 10 is inserted into the circuit 5 in series with the element 6 and the winding 8 as a tem perature compensation circuit adapted to indicate a negative temperature-resistance characteristic exceeding a positive temperature-resistance variation in the winding 8 and a resistance 9 is connected thereto in parallel with the thermistor 10 and the winding 8. Thus, as the ambient temperature rises, the shunt ratio between the series circuit of the thermistor 10 and the winding 8 and the resistance 9 varies in the direction of increase in the winding current to compensate for a decrease in the current of the element 6 associated with a drop in the voltage of a diode 4 of a power source 1 thereby checking changes in the winding current. |
