# An estimate of the load current monitor circuit rod

Posted on Dec 11, 2010

Fig. A, b, c for the test rod end clip, a positive power supply terminating test equipment, b, c end series with the load, where c is the negative side of the device. Shu is th

e sensing resistance measurements, loads of people because of its string loop, so it has a direct perception of the size of the load current. Since the product is less resistance, without affecting the load are functioning properly. Op amp IC. And BG composition suspension voltage follower, so flow through R, the load current is generated by the same pressure drop and the pressure drop on R3, Ding is flowing through the current and the voltage drop is proportional to Ri on R3, R4. R5, R6 a current/voltage conversion ratio resistors R3 with its flowing through the same current, the resulting voltage drop that is on behalf of the table the size of the load current. Such as K 2 block is located, if the load current is 1A, then the pressure drop immediately to O.IV, also O.IV drop on R3, which the current imA, then the voltage drop across Rs is 1V, because this 2 block conversion ratio IV/a. Similarly, the conversion ratio is 1 block 10V/A, 3-speed conversion ratio O.IV/A. Shaped display driver circuit consists of a linear ten point/line driver as the LM3914, IC, 7-pin output reference voltage of 1.25V, obtained from the RP IV sent an internal voltage divider as ten comparator reference voltage, while RP also determines the LEDl - LEDio operating current size, generally IF 1.25 x 10/RP. To make IC2 stable, filter capacitor C 3 is preferably close to the positive power supply pin. Fig 2 - 66 (a) of the resistor horse, R3, R4 Yun high precision, the general should be up to l% level. If the load current is greater, Shu can take 0010, op amp Ic, should take the high input impedance type, such as CA3130, CA340, LF356, TL081 and the like. It is noteworthy that in Figure 2- 66 (a) applies only to the supply voltage +3 a 18V device estimate. Figure 2 - 66 (Japan) also found that the current estimate of the display range Display resolution section of its tenth, and the load current increases, the more coarse resolution estimate results. To this end, FIG. 2 - 66 (a) may be employed in the right side of the broken line in Fig. 2 - 66 (b) bar-shaped display shown, this circuit is range resolution than Figure 2 - 66 (a) circuit is reduced by half.

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